src/Compilers/CSharp/Test/Emit2/CodeGen/CodeGenCallTests.cs - main - githubmirror/roslyn

src/Compilers/CSharp/Test/Emit2/CodeGen/CodeGenCallTests.cs
36 547 строк1 MB
Fred Silberberg
Enable runtime async tests (#80362)
04 ноя 2025, 04:33
04 ноя 2025, 04:33dfef4c1
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#nullable disable

using System;
using System.IO;
using System.Linq;
using System.Threading;
using Microsoft.CodeAnalysis.CSharp.Emit;
using Microsoft.CodeAnalysis.CSharp.Symbols;
using Microsoft.CodeAnalysis.CSharp.Test.Utilities;
using Microsoft.CodeAnalysis.Emit;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Test.Utilities;
using Xunit;

namespace Microsoft.CodeAnalysis.CSharp.UnitTests.CodeGen
{
    public class CodeGenCallTests : CSharpTestBase
    {
        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(item1);

        var item2 = new Item {Name = ""2""};
        Call2(item2);
    }

    static void Call1<T>(T item) where T : class, IMoveable
    {
        item.GetName(GetOffset(ref item));
    }

    static void Call2<T>(T item) where T : IMoveable
    {
        item.GetName(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";
            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       19 (0x13)
  .maxstack  2
  IL_0000:  ldarg.0
  IL_0001:  box        ""T""
  IL_0006:  ldarga.s   V_0
  IL_0008:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000d:  callvirt   ""void IMoveable.GetName(int)""
  IL_0012:  ret
}
");

            verifier.VerifyIL("Program.Call2<T>",
@"
{
  // Code size       45 (0x2d)
  .maxstack  2
  .locals init (T V_0)
  IL_0000:  ldarga.s   V_0
  IL_0002:  ldloca.s   V_0
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_001a
  IL_0012:  ldobj      ""T""
  IL_0017:  stloc.0
  IL_0018:  ldloca.s   V_0
  IL_001a:  ldarga.s   V_0
  IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""void IMoveable.GetName(int)""
  IL_002c:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(item1);

        var item2 = new Item {Name = ""2""};
        Call2(item2);
    }

    static void Call1<T>(T item) where T : struct, IMoveable
    {
        item.GetName(GetOffset(ref item));
    }

    static void Call2<T>(T item) where T : IMoveable
    {
        item.GetName(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position GetName for item '-1'
Position GetName for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       21 (0x15)
  .maxstack  2
  IL_0000:  ldarga.s   V_0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  constrained. ""T""
  IL_000f:  callvirt   ""void IMoveable.GetName(int)""
  IL_0014:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(ref item1);

        var item2 = new Item {Name = ""2""};
        Call2(ref item2);
    }

    static void Call1<T>(ref T item) where T : class, IMoveable
    {
        item.GetName(GetOffset(ref item));
    }

    static void Call2<T>(ref T item) where T : IMoveable
    {
        item.GetName(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
      // Code size       23 (0x17)
  .maxstack  2
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  box        ""T""
  IL_000b:  ldarg.0
  IL_000c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0011:  callvirt   ""void IMoveable.GetName(int)""
  IL_0016:  ret
}
");

            verifier.VerifyIL("Program.Call2<T>",
@"
{
  // Code size       43 (0x2b)
  .maxstack  2
  .locals init (T V_0)
  IL_0000:  ldarg.0
  IL_0001:  ldloca.s   V_0
  IL_0003:  initobj    ""T""
  IL_0009:  ldloc.0
  IL_000a:  box        ""T""
  IL_000f:  brtrue.s   IL_0019
  IL_0011:  ldobj      ""T""
  IL_0016:  stloc.0
  IL_0017:  ldloca.s   V_0
  IL_0019:  ldarg.0
  IL_001a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_001f:  constrained. ""T""
  IL_0025:  callvirt   ""void IMoveable.GetName(int)""
  IL_002a:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(ref item1);

        var item2 = new Item {Name = ""2""};
        Call2(ref item2);
    }

    static void Call1<T>(ref T item) where T : struct, IMoveable
    {
        item.GetName(GetOffset(ref item));
    }

    static void Call2<T>(ref T item) where T : IMoveable
    {
        item.GetName(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position GetName for item '-1'
Position GetName for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       19 (0x13)
  .maxstack  2
  IL_0000:  ldarg.0
  IL_0001:  ldarg.0
  IL_0002:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0007:  constrained. ""T""
  IL_000d:  callvirt   ""void IMoveable.GetName(int)""
  IL_0012:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Call1(item1);

        var item2 = new Item {Name = ""2""};
        await Call2(item2);
    }

    static async Task Call1<T>(T item) where T : class, IMoveable
    {
        item.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }

    static async Task Call2<T>(T item) where T : IMoveable
    {
        item.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      195 (0xc3)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0055
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Call1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.2
    IL_002c:  ldloca.s   V_2
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0071
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.2
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_2
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_0053:  leave.s    IL_00c2
    IL_0055:  ldarg.0
    IL_0056:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_005b:  stloc.2
    IL_005c:  ldarg.0
    IL_005d:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0062:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0068:  ldarg.0
    IL_0069:  ldc.i4.m1
    IL_006a:  dup
    IL_006b:  stloc.0
    IL_006c:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0071:  ldloca.s   V_2
    IL_0073:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0078:  stloc.1
    IL_0079:  ldarg.0
    IL_007a:  ldfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_007f:  box        ""T""
    IL_0084:  ldloc.1
    IL_0085:  callvirt   ""void IMoveable.GetName(int)""
    IL_008a:  ldarg.0
    IL_008b:  ldflda     ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0090:  initobj    ""T""
    IL_0096:  leave.s    IL_00af
  }
  catch System.Exception
  {
    IL_0098:  stloc.3
    IL_0099:  ldarg.0
    IL_009a:  ldc.i4.s   -2
    IL_009c:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00a7:  ldloc.3
    IL_00a8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ad:  leave.s    IL_00c2
  }
  IL_00af:  ldarg.0
  IL_00b0:  ldc.i4.s   -2
  IL_00b2:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_00b7:  ldarg.0
  IL_00b8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_00bd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00c2:  ret
}
");

            verifier.VerifyIL("Program.<Call2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      241 (0xf1)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0068
    IL_000a:  ldloca.s   V_2
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.2
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Call2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Call2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.3
    IL_003c:  ldloca.s   V_3
    IL_003e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0043:  brtrue.s   IL_0084
    IL_0045:  ldarg.0
    IL_0046:  ldc.i4.0
    IL_0047:  dup
    IL_0048:  stloc.0
    IL_0049:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_004e:  ldarg.0
    IL_004f:  ldloc.3
    IL_0050:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_005b:  ldloca.s   V_3
    IL_005d:  ldarg.0
    IL_005e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call2>d__2<T>)""
    IL_0063:  leave      IL_00f0
    IL_0068:  ldarg.0
    IL_0069:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_006e:  stloc.3
    IL_006f:  ldarg.0
    IL_0070:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_0075:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007b:  ldarg.0
    IL_007c:  ldc.i4.m1
    IL_007d:  dup
    IL_007e:  stloc.0
    IL_007f:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0084:  ldloca.s   V_3
    IL_0086:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008b:  stloc.1
    IL_008c:  ldloca.s   V_2
    IL_008e:  initobj    ""T""
    IL_0094:  ldloc.2
    IL_0095:  box        ""T""
    IL_009a:  brtrue.s   IL_00a4
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_00a2:  br.s       IL_00aa
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""T Program.<Call2>d__2<T>.item""
    IL_00aa:  ldloc.1
    IL_00ab:  constrained. ""T""
    IL_00b1:  callvirt   ""void IMoveable.GetName(int)""
    IL_00b6:  ldarg.0
    IL_00b7:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_00bc:  initobj    ""T""
    IL_00c2:  leave.s    IL_00dd
  }
  catch System.Exception
  {
    IL_00c4:  stloc.s    V_4
    IL_00c6:  ldarg.0
    IL_00c7:  ldc.i4.s   -2
    IL_00c9:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_00ce:  ldarg.0
    IL_00cf:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_00d4:  ldloc.s    V_4
    IL_00d6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00db:  leave.s    IL_00f0
  }
  IL_00dd:  ldarg.0
  IL_00de:  ldc.i4.s   -2
  IL_00e0:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_00e5:  ldarg.0
  IL_00e6:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
  IL_00eb:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00f0:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Call1(item1);

        var item2 = new Item {Name = ""2""};
        await Call2(item2);
    }

    static async Task Call1<T>(T item) where T : struct, IMoveable
    {
        item.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }

    static async Task Call2<T>(T item) where T : IMoveable
    {
        item.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position GetName for item '-1'
Position GetName for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      172 (0xac)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0049
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.2
    IL_0020:  ldloca.s   V_2
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0065
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.2
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_2
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_0047:  leave.s    IL_00ab
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_004f:  stloc.2
    IL_0050:  ldarg.0
    IL_0051:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0056:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005c:  ldarg.0
    IL_005d:  ldc.i4.m1
    IL_005e:  dup
    IL_005f:  stloc.0
    IL_0060:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0065:  ldloca.s   V_2
    IL_0067:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006c:  stloc.1
    IL_006d:  ldarg.0
    IL_006e:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_0073:  ldloc.1
    IL_0074:  constrained. ""T""
    IL_007a:  callvirt   ""void IMoveable.GetName(int)""
    IL_007f:  leave.s    IL_0098
  }
  catch System.Exception
  {
    IL_0081:  stloc.3
    IL_0082:  ldarg.0
    IL_0083:  ldc.i4.s   -2
    IL_0085:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_008a:  ldarg.0
    IL_008b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_0090:  ldloc.3
    IL_0091:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0096:  leave.s    IL_00ab
  }
  IL_0098:  ldarg.0
  IL_0099:  ldc.i4.s   -2
  IL_009b:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_00a0:  ldarg.0
  IL_00a1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_00a6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ab:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Class_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Call1(item1);

        var item2 = new Item {Name = ""2""};
        await Call2(item2);
    }

    static async Task Call1<T>(T item) where T : class, IMoveable
    {
        await Task.Yield();
        item.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }

    static async Task Call2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      300 (0x12c)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00bb
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Call1>d__1<T>)""
    IL_0046:  leave      IL_012b
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldarg.0
    IL_0070:  ldfld      ""T Program.<Call1>d__1<T>.item""
    IL_0075:  stfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_007a:  ldarg.0
    IL_007b:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_0080:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0085:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_008a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_008f:  stloc.s    V_4
    IL_0091:  ldloca.s   V_4
    IL_0093:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0098:  brtrue.s   IL_00d8
    IL_009a:  ldarg.0
    IL_009b:  ldc.i4.1
    IL_009c:  dup
    IL_009d:  stloc.0
    IL_009e:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00a3:  ldarg.0
    IL_00a4:  ldloc.s    V_4
    IL_00a6:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_00ab:  ldarg.0
    IL_00ac:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00b1:  ldloca.s   V_4
    IL_00b3:  ldarg.0
    IL_00b4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_00b9:  leave.s    IL_012b
    IL_00bb:  ldarg.0
    IL_00bc:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_00c1:  stloc.s    V_4
    IL_00c3:  ldarg.0
    IL_00c4:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_00c9:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00cf:  ldarg.0
    IL_00d0:  ldc.i4.m1
    IL_00d1:  dup
    IL_00d2:  stloc.0
    IL_00d3:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00d8:  ldloca.s   V_4
    IL_00da:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00df:  stloc.3
    IL_00e0:  ldarg.0
    IL_00e1:  ldfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_00e6:  box        ""T""
    IL_00eb:  ldloc.3
    IL_00ec:  callvirt   ""void IMoveable.GetName(int)""
    IL_00f1:  ldarg.0
    IL_00f2:  ldflda     ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_00f7:  initobj    ""T""
    IL_00fd:  leave.s    IL_0118
  }
  catch System.Exception
  {
    IL_00ff:  stloc.s    V_5
    IL_0101:  ldarg.0
    IL_0102:  ldc.i4.s   -2
    IL_0104:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0109:  ldarg.0
    IL_010a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_010f:  ldloc.s    V_5
    IL_0111:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0116:  leave.s    IL_012b
  }
  IL_0118:  ldarg.0
  IL_0119:  ldc.i4.s   -2
  IL_011b:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0120:  ldarg.0
  IL_0121:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_0126:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_012b:  ret
}
");

            verifier.VerifyIL("Program.<Call2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      346 (0x15a)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00cf
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call2>d__2<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Call2>d__2<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Call2>d__2<T>)""
    IL_0046:  leave      IL_0159
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call2>d__2<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call2>d__2<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldloca.s   V_4
    IL_0070:  initobj    ""T""
    IL_0076:  ldloc.s    V_4
    IL_0078:  box        ""T""
    IL_007d:  brtrue.s   IL_008b
    IL_007f:  ldarg.0
    IL_0080:  ldarg.0
    IL_0081:  ldfld      ""T Program.<Call2>d__2<T>.item""
    IL_0086:  stfld      ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""T Program.<Call2>d__2<T>.item""
    IL_0091:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0096:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_009b:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00a0:  stloc.s    V_5
    IL_00a2:  ldloca.s   V_5
    IL_00a4:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00a9:  brtrue.s   IL_00ec
    IL_00ab:  ldarg.0
    IL_00ac:  ldc.i4.1
    IL_00ad:  dup
    IL_00ae:  stloc.0
    IL_00af:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_00b4:  ldarg.0
    IL_00b5:  ldloc.s    V_5
    IL_00b7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__2""
    IL_00bc:  ldarg.0
    IL_00bd:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_00c2:  ldloca.s   V_5
    IL_00c4:  ldarg.0
    IL_00c5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call2>d__2<T>)""
    IL_00ca:  leave      IL_0159
    IL_00cf:  ldarg.0
    IL_00d0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__2""
    IL_00d5:  stloc.s    V_5
    IL_00d7:  ldarg.0
    IL_00d8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__2""
    IL_00dd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00e3:  ldarg.0
    IL_00e4:  ldc.i4.m1
    IL_00e5:  dup
    IL_00e6:  stloc.0
    IL_00e7:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_00ec:  ldloca.s   V_5
    IL_00ee:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00f3:  stloc.3
    IL_00f4:  ldloca.s   V_4
    IL_00f6:  initobj    ""T""
    IL_00fc:  ldloc.s    V_4
    IL_00fe:  box        ""T""
    IL_0103:  brtrue.s   IL_010d
    IL_0105:  ldarg.0
    IL_0106:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_010b:  br.s       IL_0113
    IL_010d:  ldarg.0
    IL_010e:  ldflda     ""T Program.<Call2>d__2<T>.item""
    IL_0113:  ldloc.3
    IL_0114:  constrained. ""T""
    IL_011a:  callvirt   ""void IMoveable.GetName(int)""
    IL_011f:  ldarg.0
    IL_0120:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_0125:  initobj    ""T""
    IL_012b:  leave.s    IL_0146
  }
  catch System.Exception
  {
    IL_012d:  stloc.s    V_6
    IL_012f:  ldarg.0
    IL_0130:  ldc.i4.s   -2
    IL_0132:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0137:  ldarg.0
    IL_0138:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_013d:  ldloc.s    V_6
    IL_013f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0144:  leave.s    IL_0159
  }
  IL_0146:  ldarg.0
  IL_0147:  ldc.i4.s   -2
  IL_0149:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_014e:  ldarg.0
  IL_014f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
  IL_0154:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0159:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Struct_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Call1(item1);

        var item2 = new Item {Name = ""2""};
        await Call2(item2);
    }

    static async Task Call1<T>(T item) where T : struct, IMoveable
    {
        await Task.Yield();
        item.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }

    static async Task Call2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position GetName for item '-1'
Position GetName for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      277 (0x115)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00af
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Call1>d__1<T>)""
    IL_0046:  leave      IL_0114
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_0074:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0079:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_007e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0083:  stloc.s    V_4
    IL_0085:  ldloca.s   V_4
    IL_0087:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_008c:  brtrue.s   IL_00cc
    IL_008e:  ldarg.0
    IL_008f:  ldc.i4.1
    IL_0090:  dup
    IL_0091:  stloc.0
    IL_0092:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0097:  ldarg.0
    IL_0098:  ldloc.s    V_4
    IL_009a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_009f:  ldarg.0
    IL_00a0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00a5:  ldloca.s   V_4
    IL_00a7:  ldarg.0
    IL_00a8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_00ad:  leave.s    IL_0114
    IL_00af:  ldarg.0
    IL_00b0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_00b5:  stloc.s    V_4
    IL_00b7:  ldarg.0
    IL_00b8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_00bd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00c3:  ldarg.0
    IL_00c4:  ldc.i4.m1
    IL_00c5:  dup
    IL_00c6:  stloc.0
    IL_00c7:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00cc:  ldloca.s   V_4
    IL_00ce:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00d3:  stloc.3
    IL_00d4:  ldarg.0
    IL_00d5:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_00da:  ldloc.3
    IL_00db:  constrained. ""T""
    IL_00e1:  callvirt   ""void IMoveable.GetName(int)""
    IL_00e6:  leave.s    IL_0101
  }
  catch System.Exception
  {
    IL_00e8:  stloc.s    V_5
    IL_00ea:  ldarg.0
    IL_00eb:  ldc.i4.s   -2
    IL_00ed:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00f2:  ldarg.0
    IL_00f3:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00f8:  ldloc.s    V_5
    IL_00fa:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ff:  leave.s    IL_0114
  }
  IL_0101:  ldarg.0
  IL_0102:  ldc.i4.s   -2
  IL_0104:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0109:  ldarg.0
  IL_010a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_010f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0114:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Class_Async_01_ThroughArray()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Item2 : Item {}

class Program
{
    static async Task Main()
    {
        var item1 = new[] {new Item2 {Name = ""1""}};
        await Call1((Item[])item1);

        var item2 = new[] {new Item2 {Name = ""2""}};
        await Call2((Item[])item2);
    }

    static async Task Call1<T>(T[] item) where T : class, IMoveable
    {
        item[GetArrayIndex()].GetName(await GetOffsetAsync(GetOffset(ref item)));
    }

    static async Task Call2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()].GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item2 {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }

    static int GetArrayIndex() => 0;
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      205 (0xcd)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_005f
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T[] Program.<Call1>d__1<T>.item""
    IL_0011:  call       ""int Program.GetArrayIndex()""
    IL_0016:  ldelem     ""T""
    IL_001b:  stfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0020:  ldarg.0
    IL_0021:  ldflda     ""T[] Program.<Call1>d__1<T>.item""
    IL_0026:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_002b:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0030:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0035:  stloc.2
    IL_0036:  ldloca.s   V_2
    IL_0038:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003d:  brtrue.s   IL_007b
    IL_003f:  ldarg.0
    IL_0040:  ldc.i4.0
    IL_0041:  dup
    IL_0042:  stloc.0
    IL_0043:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0048:  ldarg.0
    IL_0049:  ldloc.2
    IL_004a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_004f:  ldarg.0
    IL_0050:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_0055:  ldloca.s   V_2
    IL_0057:  ldarg.0
    IL_0058:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_005d:  leave.s    IL_00cc
    IL_005f:  ldarg.0
    IL_0060:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0065:  stloc.2
    IL_0066:  ldarg.0
    IL_0067:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_006c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0072:  ldarg.0
    IL_0073:  ldc.i4.m1
    IL_0074:  dup
    IL_0075:  stloc.0
    IL_0076:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_007b:  ldloca.s   V_2
    IL_007d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0082:  stloc.1
    IL_0083:  ldarg.0
    IL_0084:  ldfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0089:  box        ""T""
    IL_008e:  ldloc.1
    IL_008f:  callvirt   ""void IMoveable.GetName(int)""
    IL_0094:  ldarg.0
    IL_0095:  ldflda     ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_009a:  initobj    ""T""
    IL_00a0:  leave.s    IL_00b9
  }
  catch System.Exception
  {
    IL_00a2:  stloc.3
    IL_00a3:  ldarg.0
    IL_00a4:  ldc.i4.s   -2
    IL_00a6:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00ab:  ldarg.0
    IL_00ac:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00b1:  ldloc.3
    IL_00b2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00b7:  leave.s    IL_00cc
  }
  IL_00b9:  ldarg.0
  IL_00ba:  ldc.i4.s   -2
  IL_00bc:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_00c1:  ldarg.0
  IL_00c2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_00c7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00cc:  ret
}
");

            verifier.VerifyIL("Program.<Call2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      318 (0x13e)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00a1
    IL_000d:  ldarg.0
    IL_000e:  ldarg.0
    IL_000f:  ldfld      ""T[] Program.<Call2>d__2<T>.item""
    IL_0014:  stfld      ""T[] Program.<Call2>d__2<T>.<>7__wrap2""
    IL_0019:  ldarg.0
    IL_001a:  call       ""int Program.GetArrayIndex()""
    IL_001f:  stfld      ""int Program.<Call2>d__2<T>.<>7__wrap3""
    IL_0024:  ldarg.0
    IL_0025:  ldfld      ""T[] Program.<Call2>d__2<T>.<>7__wrap2""
    IL_002a:  ldarg.0
    IL_002b:  ldfld      ""int Program.<Call2>d__2<T>.<>7__wrap3""
    IL_0030:  readonly.
    IL_0032:  ldelema    ""T""
    IL_0037:  pop
    IL_0038:  ldloca.s   V_2
    IL_003a:  initobj    ""T""
    IL_0040:  ldloc.2
    IL_0041:  box        ""T""
    IL_0046:  brtrue.s   IL_005f
    IL_0048:  ldarg.0
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""T[] Program.<Call2>d__2<T>.<>7__wrap2""
    IL_004f:  ldarg.0
    IL_0050:  ldfld      ""int Program.<Call2>d__2<T>.<>7__wrap3""
    IL_0055:  ldelem     ""T""
    IL_005a:  stfld      ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""T[] Program.<Call2>d__2<T>.item""
    IL_0065:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_006a:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_006f:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0074:  stloc.3
    IL_0075:  ldloca.s   V_3
    IL_0077:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_007c:  brtrue.s   IL_00bd
    IL_007e:  ldarg.0
    IL_007f:  ldc.i4.0
    IL_0080:  dup
    IL_0081:  stloc.0
    IL_0082:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0087:  ldarg.0
    IL_0088:  ldloc.3
    IL_0089:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_008e:  ldarg.0
    IL_008f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_0094:  ldloca.s   V_3
    IL_0096:  ldarg.0
    IL_0097:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call2>d__2<T>)""
    IL_009c:  leave      IL_013d
    IL_00a1:  ldarg.0
    IL_00a2:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_00a7:  stloc.3
    IL_00a8:  ldarg.0
    IL_00a9:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_00ae:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00b4:  ldarg.0
    IL_00b5:  ldc.i4.m1
    IL_00b6:  dup
    IL_00b7:  stloc.0
    IL_00b8:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_00bd:  ldloca.s   V_3
    IL_00bf:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00c4:  stloc.1
    IL_00c5:  ldloca.s   V_2
    IL_00c7:  initobj    ""T""
    IL_00cd:  ldloc.2
    IL_00ce:  box        ""T""
    IL_00d3:  brtrue.s   IL_00dd
    IL_00d5:  ldarg.0
    IL_00d6:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_00db:  br.s       IL_00f0
    IL_00dd:  ldarg.0
    IL_00de:  ldfld      ""T[] Program.<Call2>d__2<T>.<>7__wrap2""
    IL_00e3:  ldarg.0
    IL_00e4:  ldfld      ""int Program.<Call2>d__2<T>.<>7__wrap3""
    IL_00e9:  readonly.
    IL_00eb:  ldelema    ""T""
    IL_00f0:  ldloc.1
    IL_00f1:  constrained. ""T""
    IL_00f7:  callvirt   ""void IMoveable.GetName(int)""
    IL_00fc:  ldarg.0
    IL_00fd:  ldnull
    IL_00fe:  stfld      ""T[] Program.<Call2>d__2<T>.<>7__wrap2""
    IL_0103:  ldarg.0
    IL_0104:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_0109:  initobj    ""T""
    IL_010f:  leave.s    IL_012a
  }
  catch System.Exception
  {
    IL_0111:  stloc.s    V_4
    IL_0113:  ldarg.0
    IL_0114:  ldc.i4.s   -2
    IL_0116:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_011b:  ldarg.0
    IL_011c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_0121:  ldloc.s    V_4
    IL_0123:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0128:  leave.s    IL_013d
  }
  IL_012a:  ldarg.0
  IL_012b:  ldc.i4.s   -2
  IL_012d:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_0132:  ldarg.0
  IL_0133:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
  IL_0138:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_013d:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Struct_Async_01_ThroughArray()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new[] {new Item {Name = ""1""}};
        await Call1(item1);

        var item2 = new[] {new Item {Name = ""2""}};
        await Call2(item2);
    }

    static async Task Call1<T>(T[] item) where T : struct, IMoveable
    {
        item[GetArrayIndex()].GetName(await GetOffsetAsync(GetOffset(ref item)));
    }

    static async Task Call2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()].GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }

    static int GetArrayIndex() => 0;
}
";

            var expectedOutput = @"
Position GetName for item '-1'
Position GetName for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      235 (0xeb)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0074
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T[] Program.<Call1>d__1<T>.item""
    IL_0011:  stfld      ""T[] Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  call       ""int Program.GetArrayIndex()""
    IL_001c:  stfld      ""int Program.<Call1>d__1<T>.<>7__wrap2""
    IL_0021:  ldarg.0
    IL_0022:  ldfld      ""T[] Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0027:  ldarg.0
    IL_0028:  ldfld      ""int Program.<Call1>d__1<T>.<>7__wrap2""
    IL_002d:  readonly.
    IL_002f:  ldelema    ""T""
    IL_0034:  pop
    IL_0035:  ldarg.0
    IL_0036:  ldflda     ""T[] Program.<Call1>d__1<T>.item""
    IL_003b:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_0040:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0045:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_004a:  stloc.2
    IL_004b:  ldloca.s   V_2
    IL_004d:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0052:  brtrue.s   IL_0090
    IL_0054:  ldarg.0
    IL_0055:  ldc.i4.0
    IL_0056:  dup
    IL_0057:  stloc.0
    IL_0058:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_005d:  ldarg.0
    IL_005e:  ldloc.2
    IL_005f:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0064:  ldarg.0
    IL_0065:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_006a:  ldloca.s   V_2
    IL_006c:  ldarg.0
    IL_006d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_0072:  leave.s    IL_00ea
    IL_0074:  ldarg.0
    IL_0075:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_007a:  stloc.2
    IL_007b:  ldarg.0
    IL_007c:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0081:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0087:  ldarg.0
    IL_0088:  ldc.i4.m1
    IL_0089:  dup
    IL_008a:  stloc.0
    IL_008b:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0090:  ldloca.s   V_2
    IL_0092:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0097:  stloc.1
    IL_0098:  ldarg.0
    IL_0099:  ldfld      ""T[] Program.<Call1>d__1<T>.<>7__wrap1""
    IL_009e:  ldarg.0
    IL_009f:  ldfld      ""int Program.<Call1>d__1<T>.<>7__wrap2""
    IL_00a4:  readonly.
    IL_00a6:  ldelema    ""T""
    IL_00ab:  ldloc.1
    IL_00ac:  constrained. ""T""
    IL_00b2:  callvirt   ""void IMoveable.GetName(int)""
    IL_00b7:  ldarg.0
    IL_00b8:  ldnull
    IL_00b9:  stfld      ""T[] Program.<Call1>d__1<T>.<>7__wrap1""
    IL_00be:  leave.s    IL_00d7
  }
  catch System.Exception
  {
    IL_00c0:  stloc.3
    IL_00c1:  ldarg.0
    IL_00c2:  ldc.i4.s   -2
    IL_00c4:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00c9:  ldarg.0
    IL_00ca:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00cf:  ldloc.3
    IL_00d0:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d5:  leave.s    IL_00ea
  }
  IL_00d7:  ldarg.0
  IL_00d8:  ldc.i4.s   -2
  IL_00da:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_00df:  ldarg.0
  IL_00e0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_00e5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ea:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_InterpolationHandler_Class()
        {
            var source = @"
using System;
using System.Runtime.CompilerServices;
using System.Text;


interface IMoveable
{
    string Name {get;}
    void GetName(int x, [InterpolatedStringHandlerArgument("""")] DummyHandler handler);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x, [InterpolatedStringHandlerArgument("""")] DummyHandler handler)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(item1);

        var item2 = new Item {Name = ""2""};
        Call2(item2);
    }

    static void Call1<T>(T item) where T : class, IMoveable
    {
        item.GetName(GetOffset(ref item), $""log:{0}"");
    }

    static void Call2<T>(T item) where T : IMoveable
    {
        item.GetName(GetOffset(ref item), $""log"");
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}

[InterpolatedStringHandler]
internal ref struct DummyHandler
{
    private readonly StringBuilder _builder;
    public DummyHandler(int literalLength, int formattedCount, IMoveable logger)
    {
        Console.WriteLine(""Position DummyHandler for item '{0}'"", logger.Name);
        _builder = new StringBuilder();
    }
    public string GetContent() => _builder.ToString();

    public void AppendLiteral(string s) => _builder.Append(s);
    public void AppendFormatted<T>(T t) => _builder.Append(t);
}
";

            var expectedOutput = @"
Position DummyHandler for item '1'
Position GetName for item '1'
Position DummyHandler for item '2'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(
                new[] { source, InterpolatedStringHandlerAttribute, InterpolatedStringHandlerArgumentAttribute },
                options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       57 (0x39)
  .maxstack  6
  .locals init (T V_0,
                DummyHandler V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  box        ""T""
  IL_0008:  ldarga.s   V_0
  IL_000a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000f:  ldloca.s   V_1
  IL_0011:  ldc.i4.4
  IL_0012:  ldc.i4.1
  IL_0013:  ldloc.0
  IL_0014:  box        ""T""
  IL_0019:  call       ""DummyHandler..ctor(int, int, IMoveable)""
  IL_001e:  ldloca.s   V_1
  IL_0020:  ldstr      ""log:""
  IL_0025:  call       ""void DummyHandler.AppendLiteral(string)""
  IL_002a:  ldloca.s   V_1
  IL_002c:  ldc.i4.0
  IL_002d:  call       ""void DummyHandler.AppendFormatted<int>(int)""
  IL_0032:  ldloc.1
  IL_0033:  callvirt   ""void IMoveable.GetName(int, DummyHandler)""
  IL_0038:  ret
}
");

            verifier.VerifyIL("Program.Call2<T>",
@"
{
  // Code size       86 (0x56)
  .maxstack  6
  .locals init (T& V_0,
            T V_1,
            T& V_2,
            T V_3,
            DummyHandler V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  ldloca.s   V_4
  IL_002a:  ldc.i4.3
  IL_002b:  ldc.i4.0
  IL_002c:  ldloc.0
  IL_002d:  ldobj      ""T""
  IL_0032:  box        ""T""
  IL_0037:  call       ""DummyHandler..ctor(int, int, IMoveable)""
  IL_003c:  ldloca.s   V_4
  IL_003e:  ldstr      ""log""
  IL_0043:  call       ""void DummyHandler.AppendLiteral(string)""
  IL_0048:  ldloc.s    V_4
  IL_004a:  constrained. ""T""
  IL_0050:  callvirt   ""void IMoveable.GetName(int, DummyHandler)""
  IL_0055:  ret
}
");

            CompileAndVerify(
                new[] { source, InterpolatedStringHandlerAttribute, InterpolatedStringHandlerArgumentAttribute },
                options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_InterpolationHandler_Struct()
        {
            var source = @"
using System;
using System.Runtime.CompilerServices;
using System.Text;


interface IMoveable
{
    string Name {get;}
    void GetName(int x, [InterpolatedStringHandlerArgument("""")] DummyHandler handler);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x, [InterpolatedStringHandlerArgument("""")] DummyHandler handler)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(item1);

        var item2 = new Item {Name = ""2""};
        Call2(item2);
    }

    static void Call1<T>(T item) where T : struct, IMoveable
    {
        item.GetName(GetOffset(ref item), $""log:{0}"");
    }

    static void Call2<T>(T item) where T : IMoveable
    {
        item.GetName(GetOffset(ref item), $""log"");
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}

[InterpolatedStringHandler]
internal ref struct DummyHandler
{
    private readonly StringBuilder _builder;
    public DummyHandler(int literalLength, int formattedCount, IMoveable logger)
    {
        Console.WriteLine(""Position DummyHandler for item '{0}'"", logger.Name);
        _builder = new StringBuilder();
    }
    public string GetContent() => _builder.ToString();

    public void AppendLiteral(string s) => _builder.Append(s);
    public void AppendFormatted<T>(T t) => _builder.Append(t);
}
";

            var expectedOutput = @"
Position DummyHandler for item '-1'
Position GetName for item '-1'
Position DummyHandler for item '-2'
Position GetName for item '-2'
";
            var verifier = CompileAndVerify(
                new[] { source, InterpolatedStringHandlerAttribute, InterpolatedStringHandlerArgumentAttribute },
                options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       64 (0x40)
  .maxstack  6
  .locals init (T& V_0,
                DummyHandler V_1)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldloc.0
  IL_0004:  ldarga.s   V_0
  IL_0006:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000b:  ldloca.s   V_1
  IL_000d:  ldc.i4.4
  IL_000e:  ldc.i4.1
  IL_000f:  ldloc.0
  IL_0010:  ldobj      ""T""
  IL_0015:  box        ""T""
  IL_001a:  call       ""DummyHandler..ctor(int, int, IMoveable)""
  IL_001f:  ldloca.s   V_1
  IL_0021:  ldstr      ""log:""
  IL_0026:  call       ""void DummyHandler.AppendLiteral(string)""
  IL_002b:  ldloca.s   V_1
  IL_002d:  ldc.i4.0
  IL_002e:  call       ""void DummyHandler.AppendFormatted<int>(int)""
  IL_0033:  ldloc.1
  IL_0034:  constrained. ""T""
  IL_003a:  callvirt   ""void IMoveable.GetName(int, DummyHandler)""
  IL_003f:  ret
}
");

            CompileAndVerify(
                new[] { source, InterpolatedStringHandlerAttribute, InterpolatedStringHandlerArgumentAttribute },
                options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_InterpolationHandler_Class_Ref()
        {
            var source = @"
using System;
using System.Runtime.CompilerServices;
using System.Text;


interface IMoveable
{
    string Name {get;}
    void GetName(int x, [InterpolatedStringHandlerArgument("""")] DummyHandler handler);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x, [InterpolatedStringHandlerArgument("""")] DummyHandler handler)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(ref item1);

        var item2 = new Item {Name = ""2""};
        Call2(ref item2);
    }

    static void Call1<T>(ref T item) where T : class, IMoveable
    {
        item.GetName(GetOffset(ref item), $""log:{0}"");
    }

    static void Call2<T>(ref T item) where T : IMoveable
    {
        item.GetName(GetOffset(ref item), $""log"");
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}

[InterpolatedStringHandler]
internal ref struct DummyHandler
{
    private readonly StringBuilder _builder;
    public DummyHandler(int literalLength, int formattedCount, IMoveable logger)
    {
        Console.WriteLine(""Position DummyHandler for item '{0}'"", logger.Name);
        _builder = new StringBuilder();
    }
    public string GetContent() => _builder.ToString();

    public void AppendLiteral(string s) => _builder.Append(s);
    public void AppendFormatted<T>(T t) => _builder.Append(t);
}
";

            var expectedOutput = @"
Position DummyHandler for item '1'
Position GetName for item '1'
Position DummyHandler for item '2'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(
                new[] { source, InterpolatedStringHandlerAttribute, InterpolatedStringHandlerArgumentAttribute },
                options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       61 (0x3d)
  .maxstack  6
  .locals init (T V_0,
                DummyHandler V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldloc.0
  IL_0008:  box        ""T""
  IL_000d:  ldarg.0
  IL_000e:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0013:  ldloca.s   V_1
  IL_0015:  ldc.i4.4
  IL_0016:  ldc.i4.1
  IL_0017:  ldloc.0
  IL_0018:  box        ""T""
  IL_001d:  call       ""DummyHandler..ctor(int, int, IMoveable)""
  IL_0022:  ldloca.s   V_1
  IL_0024:  ldstr      ""log:""
  IL_0029:  call       ""void DummyHandler.AppendLiteral(string)""
  IL_002e:  ldloca.s   V_1
  IL_0030:  ldc.i4.0
  IL_0031:  call       ""void DummyHandler.AppendFormatted<int>(int)""
  IL_0036:  ldloc.1
  IL_0037:  callvirt   ""void IMoveable.GetName(int, DummyHandler)""
  IL_003c:  ret
}
");

            verifier.VerifyIL("Program.Call2<T>",
@"
{
  // Code size       84 (0x54)
  .maxstack  6
  .locals init (T& V_0,
            T V_1,
            T& V_2,
            T V_3,
            DummyHandler V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_3
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.3
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_001d
  IL_0012:  ldloc.2
  IL_0013:  ldobj      ""T""
  IL_0018:  stloc.1
  IL_0019:  ldloca.s   V_1
  IL_001b:  br.s       IL_001e
  IL_001d:  ldloc.2
  IL_001e:  stloc.0
  IL_001f:  ldloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  ldloca.s   V_4
  IL_0028:  ldc.i4.3
  IL_0029:  ldc.i4.0
  IL_002a:  ldloc.0
  IL_002b:  ldobj      ""T""
  IL_0030:  box        ""T""
  IL_0035:  call       ""DummyHandler..ctor(int, int, IMoveable)""
  IL_003a:  ldloca.s   V_4
  IL_003c:  ldstr      ""log""
  IL_0041:  call       ""void DummyHandler.AppendLiteral(string)""
  IL_0046:  ldloc.s    V_4
  IL_0048:  constrained. ""T""
  IL_004e:  callvirt   ""void IMoveable.GetName(int, DummyHandler)""
  IL_0053:  ret
}
");

            CompileAndVerify(
                new[] { source, InterpolatedStringHandlerAttribute, InterpolatedStringHandlerArgumentAttribute },
                options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_InterpolationHandler_Struct_Ref()
        {
            var source = @"
using System;
using System.Runtime.CompilerServices;
using System.Text;


interface IMoveable
{
    string Name {get;}
    void GetName(int x, [InterpolatedStringHandlerArgument("""")] DummyHandler handler);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x, [InterpolatedStringHandlerArgument("""")] DummyHandler handler)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(ref item1);

        var item2 = new Item {Name = ""2""};
        Call2(ref item2);
    }

    static void Call1<T>(ref T item) where T : struct, IMoveable
    {
        item.GetName(GetOffset(ref item), $""log:{0}"");
    }

    static void Call2<T>(ref T item) where T : IMoveable
    {
        item.GetName(GetOffset(ref item), $""log"");
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}

[InterpolatedStringHandler]
internal ref struct DummyHandler
{
    private readonly StringBuilder _builder;
    public DummyHandler(int literalLength, int formattedCount, IMoveable logger)
    {
        Console.WriteLine(""Position DummyHandler for item '{0}'"", logger.Name);
        _builder = new StringBuilder();
    }
    public string GetContent() => _builder.ToString();

    public void AppendLiteral(string s) => _builder.Append(s);
    public void AppendFormatted<T>(T t) => _builder.Append(t);
}
";

            var expectedOutput = @"
Position DummyHandler for item '-1'
Position GetName for item '-1'
Position DummyHandler for item '-2'
Position GetName for item '-2'
";
            var verifier = CompileAndVerify(
                new[] { source, InterpolatedStringHandlerAttribute, InterpolatedStringHandlerArgumentAttribute },
                options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       62 (0x3e)
  .maxstack  6
  .locals init (T& V_0,
                DummyHandler V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  ldarg.0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  ldloca.s   V_1
  IL_000b:  ldc.i4.4
  IL_000c:  ldc.i4.1
  IL_000d:  ldloc.0
  IL_000e:  ldobj      ""T""
  IL_0013:  box        ""T""
  IL_0018:  call       ""DummyHandler..ctor(int, int, IMoveable)""
  IL_001d:  ldloca.s   V_1
  IL_001f:  ldstr      ""log:""
  IL_0024:  call       ""void DummyHandler.AppendLiteral(string)""
  IL_0029:  ldloca.s   V_1
  IL_002b:  ldc.i4.0
  IL_002c:  call       ""void DummyHandler.AppendFormatted<int>(int)""
  IL_0031:  ldloc.1
  IL_0032:  constrained. ""T""
  IL_0038:  callvirt   ""void IMoveable.GetName(int, DummyHandler)""
  IL_003d:  ret
}
");

            CompileAndVerify(
                new[] { source, InterpolatedStringHandlerAttribute, InterpolatedStringHandlerArgumentAttribute },
                options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Conditional_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(item1);

        var item2 = new Item {Name = ""2""};
        Call2(item2);
    }

    static void Call1<T>(T item) where T : class, IMoveable
    {
        item?.GetName(GetOffset(ref item));
    }

    static void Call2<T>(T item) where T : IMoveable
    {
        item?.GetName(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       24 (0x18)
  .maxstack  2
  IL_0000:  ldarg.0
  IL_0001:  box        ""T""
  IL_0006:  dup
  IL_0007:  brtrue.s   IL_000b
  IL_0009:  pop
  IL_000a:  ret
  IL_000b:  ldarga.s   V_0
  IL_000d:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0012:  callvirt   ""void IMoveable.GetName(int)""
  IL_0017:  ret
}
");

            verifier.VerifyIL("Program.Call2<T>",
@"
{
  // Code size       55 (0x37)
  .maxstack  2
  .locals init (T V_0)
  IL_0000:  ldarga.s   V_0
  IL_0002:  ldloca.s   V_0
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_0024
  IL_0012:  ldobj      ""T""
  IL_0017:  stloc.0
  IL_0018:  ldloca.s   V_0
  IL_001a:  ldloc.0
  IL_001b:  box        ""T""
  IL_0020:  brtrue.s   IL_0024
  IL_0022:  pop
  IL_0023:  ret
  IL_0024:  ldarga.s   V_0
  IL_0026:  call       ""int Program.GetOffset<T>(ref T)""
  IL_002b:  constrained. ""T""
  IL_0031:  callvirt   ""void IMoveable.GetName(int)""
  IL_0036:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Conditional_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item2 = new Item {Name = ""2""};
        Call2(item2);
    }

    static void Call2<T>(T item) where T : IMoveable
    {
        item?.GetName(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position GetName for item '-1'
";
            CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Conditional_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(ref item1);

        var item2 = new Item {Name = ""2""};
        Call2(ref item2);
    }

    static void Call1<T>(ref T item) where T : class, IMoveable
    {
        item?.GetName(GetOffset(ref item));
    }

    static void Call2<T>(ref T item) where T : IMoveable
    {
        item?.GetName(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       28 (0x1c)
  .maxstack  2
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  box        ""T""
  IL_000b:  dup
  IL_000c:  brtrue.s   IL_0010
  IL_000e:  pop
  IL_000f:  ret
  IL_0010:  ldarg.0
  IL_0011:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0016:  callvirt   ""void IMoveable.GetName(int)""
  IL_001b:  ret
}
");

            verifier.VerifyIL("Program.Call2<T>",
@"
{
  // Code size       53 (0x35)
  .maxstack  2
  .locals init (T V_0)
  IL_0000:  ldarg.0
  IL_0001:  ldloca.s   V_0
  IL_0003:  initobj    ""T""
  IL_0009:  ldloc.0
  IL_000a:  box        ""T""
  IL_000f:  brtrue.s   IL_0023
  IL_0011:  ldobj      ""T""
  IL_0016:  stloc.0
  IL_0017:  ldloca.s   V_0
  IL_0019:  ldloc.0
  IL_001a:  box        ""T""
  IL_001f:  brtrue.s   IL_0023
  IL_0021:  pop
  IL_0022:  ret
  IL_0023:  ldarg.0
  IL_0024:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0029:  constrained. ""T""
  IL_002f:  callvirt   ""void IMoveable.GetName(int)""
  IL_0034:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Conditional_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item2 = new Item {Name = ""2""};
        Call2(ref item2);
    }

    static void Call2<T>(ref T item) where T : IMoveable
    {
        item?.GetName(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position GetName for item '-1'
";
            CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Conditional_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Call1(item1);

        var item2 = new Item {Name = ""2""};
        await Call2(item2);
    }

    static async Task Call1<T>(T item) where T : class, IMoveable
    {
        item?.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }

    static async Task Call2<T>(T item) where T : IMoveable
    {
        item?.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      208 (0xd0)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0062
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Call1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_001c:  box        ""T""
    IL_0021:  brfalse.s  IL_0097
    IL_0023:  ldarg.0
    IL_0024:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_0029:  call       ""int Program.GetOffset<T>(ref T)""
    IL_002e:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0033:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0038:  stloc.2
    IL_0039:  ldloca.s   V_2
    IL_003b:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0040:  brtrue.s   IL_007e
    IL_0042:  ldarg.0
    IL_0043:  ldc.i4.0
    IL_0044:  dup
    IL_0045:  stloc.0
    IL_0046:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_004b:  ldarg.0
    IL_004c:  ldloc.2
    IL_004d:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_0058:  ldloca.s   V_2
    IL_005a:  ldarg.0
    IL_005b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_0060:  leave.s    IL_00cf
    IL_0062:  ldarg.0
    IL_0063:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0068:  stloc.2
    IL_0069:  ldarg.0
    IL_006a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_006f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0075:  ldarg.0
    IL_0076:  ldc.i4.m1
    IL_0077:  dup
    IL_0078:  stloc.0
    IL_0079:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_007e:  ldloca.s   V_2
    IL_0080:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0085:  stloc.1
    IL_0086:  ldarg.0
    IL_0087:  ldfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_008c:  box        ""T""
    IL_0091:  ldloc.1
    IL_0092:  callvirt   ""void IMoveable.GetName(int)""
    IL_0097:  ldarg.0
    IL_0098:  ldflda     ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_009d:  initobj    ""T""
    IL_00a3:  leave.s    IL_00bc
  }
  catch System.Exception
  {
    IL_00a5:  stloc.3
    IL_00a6:  ldarg.0
    IL_00a7:  ldc.i4.s   -2
    IL_00a9:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00ae:  ldarg.0
    IL_00af:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00b4:  ldloc.3
    IL_00b5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ba:  leave.s    IL_00cf
  }
  IL_00bc:  ldarg.0
  IL_00bd:  ldc.i4.s   -2
  IL_00bf:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_00c4:  ldarg.0
  IL_00c5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_00ca:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00cf:  ret
}
");

            verifier.VerifyIL("Program.<Call2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      257 (0x101)
  .maxstack  3
  .locals init (int V_0,
                T V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0078
    IL_000a:  ldloca.s   V_1
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.1
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0036
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Call2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldfld      ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_002c:  box        ""T""
    IL_0031:  brfalse    IL_00c6
    IL_0036:  ldarg.0
    IL_0037:  ldflda     ""T Program.<Call2>d__2<T>.item""
    IL_003c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0041:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0046:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_004b:  stloc.3
    IL_004c:  ldloca.s   V_3
    IL_004e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0053:  brtrue.s   IL_0094
    IL_0055:  ldarg.0
    IL_0056:  ldc.i4.0
    IL_0057:  dup
    IL_0058:  stloc.0
    IL_0059:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_005e:  ldarg.0
    IL_005f:  ldloc.3
    IL_0060:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_0065:  ldarg.0
    IL_0066:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_006b:  ldloca.s   V_3
    IL_006d:  ldarg.0
    IL_006e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call2>d__2<T>)""
    IL_0073:  leave      IL_0100
    IL_0078:  ldarg.0
    IL_0079:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_007e:  stloc.3
    IL_007f:  ldarg.0
    IL_0080:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__1""
    IL_0085:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_008b:  ldarg.0
    IL_008c:  ldc.i4.m1
    IL_008d:  dup
    IL_008e:  stloc.0
    IL_008f:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0094:  ldloca.s   V_3
    IL_0096:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_009b:  stloc.2
    IL_009c:  ldloca.s   V_1
    IL_009e:  initobj    ""T""
    IL_00a4:  ldloc.1
    IL_00a5:  box        ""T""
    IL_00aa:  brtrue.s   IL_00b4
    IL_00ac:  ldarg.0
    IL_00ad:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_00b2:  br.s       IL_00ba
    IL_00b4:  ldarg.0
    IL_00b5:  ldflda     ""T Program.<Call2>d__2<T>.item""
    IL_00ba:  ldloc.2
    IL_00bb:  constrained. ""T""
    IL_00c1:  callvirt   ""void IMoveable.GetName(int)""
    IL_00c6:  ldarg.0
    IL_00c7:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_00cc:  initobj    ""T""
    IL_00d2:  leave.s    IL_00ed
  }
  catch System.Exception
  {
    IL_00d4:  stloc.s    V_4
    IL_00d6:  ldarg.0
    IL_00d7:  ldc.i4.s   -2
    IL_00d9:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_00de:  ldarg.0
    IL_00df:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_00e4:  ldloc.s    V_4
    IL_00e6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00eb:  leave.s    IL_0100
  }
  IL_00ed:  ldarg.0
  IL_00ee:  ldc.i4.s   -2
  IL_00f0:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_00f5:  ldarg.0
  IL_00f6:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
  IL_00fb:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0100:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Conditional_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item2 = new Item {Name = ""2""};
        await Call2(item2);
    }

    static async Task Call2<T>(T item) where T : IMoveable
    {
        item?.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position GetName for item '-1'
";
            CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Conditional_Class_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Call1(item1);

        var item2 = new Item {Name = ""2""};
        await Call2(item2);
    }

    static async Task Call1<T>(T item) where T : class, IMoveable
    {
        await Task.Yield();
        item?.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }

    static async Task Call2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item?.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      313 (0x139)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00c8
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Call1>d__1<T>)""
    IL_0046:  leave      IL_0138
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldarg.0
    IL_0070:  ldfld      ""T Program.<Call1>d__1<T>.item""
    IL_0075:  stfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_007a:  ldarg.0
    IL_007b:  ldfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0080:  box        ""T""
    IL_0085:  brfalse.s  IL_00fe
    IL_0087:  ldarg.0
    IL_0088:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_008d:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0092:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0097:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_009c:  stloc.s    V_4
    IL_009e:  ldloca.s   V_4
    IL_00a0:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00a5:  brtrue.s   IL_00e5
    IL_00a7:  ldarg.0
    IL_00a8:  ldc.i4.1
    IL_00a9:  dup
    IL_00aa:  stloc.0
    IL_00ab:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00b0:  ldarg.0
    IL_00b1:  ldloc.s    V_4
    IL_00b3:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_00b8:  ldarg.0
    IL_00b9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00be:  ldloca.s   V_4
    IL_00c0:  ldarg.0
    IL_00c1:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_00c6:  leave.s    IL_0138
    IL_00c8:  ldarg.0
    IL_00c9:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_00ce:  stloc.s    V_4
    IL_00d0:  ldarg.0
    IL_00d1:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__2""
    IL_00d6:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00dc:  ldarg.0
    IL_00dd:  ldc.i4.m1
    IL_00de:  dup
    IL_00df:  stloc.0
    IL_00e0:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00e5:  ldloca.s   V_4
    IL_00e7:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00ec:  stloc.3
    IL_00ed:  ldarg.0
    IL_00ee:  ldfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_00f3:  box        ""T""
    IL_00f8:  ldloc.3
    IL_00f9:  callvirt   ""void IMoveable.GetName(int)""
    IL_00fe:  ldarg.0
    IL_00ff:  ldflda     ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0104:  initobj    ""T""
    IL_010a:  leave.s    IL_0125
  }
  catch System.Exception
  {
    IL_010c:  stloc.s    V_5
    IL_010e:  ldarg.0
    IL_010f:  ldc.i4.s   -2
    IL_0111:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0116:  ldarg.0
    IL_0117:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_011c:  ldloc.s    V_5
    IL_011e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0123:  leave.s    IL_0138
  }
  IL_0125:  ldarg.0
  IL_0126:  ldc.i4.s   -2
  IL_0128:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_012d:  ldarg.0
  IL_012e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_0133:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0138:  ret
}
");

            verifier.VerifyIL("Program.<Call2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      362 (0x16a)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                T V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00de
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call2>d__2<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Call2>d__2<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Call2>d__2<T>)""
    IL_0046:  leave      IL_0169
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call2>d__2<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Call2>d__2<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldloca.s   V_3
    IL_0070:  initobj    ""T""
    IL_0076:  ldloc.3
    IL_0077:  box        ""T""
    IL_007c:  brtrue.s   IL_009a
    IL_007e:  ldarg.0
    IL_007f:  ldarg.0
    IL_0080:  ldfld      ""T Program.<Call2>d__2<T>.item""
    IL_0085:  stfld      ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_008a:  ldarg.0
    IL_008b:  ldfld      ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_0090:  box        ""T""
    IL_0095:  brfalse    IL_012f
    IL_009a:  ldarg.0
    IL_009b:  ldflda     ""T Program.<Call2>d__2<T>.item""
    IL_00a0:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00a5:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00aa:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00af:  stloc.s    V_5
    IL_00b1:  ldloca.s   V_5
    IL_00b3:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00b8:  brtrue.s   IL_00fb
    IL_00ba:  ldarg.0
    IL_00bb:  ldc.i4.1
    IL_00bc:  dup
    IL_00bd:  stloc.0
    IL_00be:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_00c3:  ldarg.0
    IL_00c4:  ldloc.s    V_5
    IL_00c6:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__2""
    IL_00cb:  ldarg.0
    IL_00cc:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_00d1:  ldloca.s   V_5
    IL_00d3:  ldarg.0
    IL_00d4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call2>d__2<T>)""
    IL_00d9:  leave      IL_0169
    IL_00de:  ldarg.0
    IL_00df:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__2""
    IL_00e4:  stloc.s    V_5
    IL_00e6:  ldarg.0
    IL_00e7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call2>d__2<T>.<>u__2""
    IL_00ec:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00f2:  ldarg.0
    IL_00f3:  ldc.i4.m1
    IL_00f4:  dup
    IL_00f5:  stloc.0
    IL_00f6:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_00fb:  ldloca.s   V_5
    IL_00fd:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0102:  stloc.s    V_4
    IL_0104:  ldloca.s   V_3
    IL_0106:  initobj    ""T""
    IL_010c:  ldloc.3
    IL_010d:  box        ""T""
    IL_0112:  brtrue.s   IL_011c
    IL_0114:  ldarg.0
    IL_0115:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_011a:  br.s       IL_0122
    IL_011c:  ldarg.0
    IL_011d:  ldflda     ""T Program.<Call2>d__2<T>.item""
    IL_0122:  ldloc.s    V_4
    IL_0124:  constrained. ""T""
    IL_012a:  callvirt   ""void IMoveable.GetName(int)""
    IL_012f:  ldarg.0
    IL_0130:  ldflda     ""T Program.<Call2>d__2<T>.<>7__wrap1""
    IL_0135:  initobj    ""T""
    IL_013b:  leave.s    IL_0156
  }
  catch System.Exception
  {
    IL_013d:  stloc.s    V_6
    IL_013f:  ldarg.0
    IL_0140:  ldc.i4.s   -2
    IL_0142:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
    IL_0147:  ldarg.0
    IL_0148:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
    IL_014d:  ldloc.s    V_6
    IL_014f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0154:  leave.s    IL_0169
  }
  IL_0156:  ldarg.0
  IL_0157:  ldc.i4.s   -2
  IL_0159:  stfld      ""int Program.<Call2>d__2<T>.<>1__state""
  IL_015e:  ldarg.0
  IL_015f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call2>d__2<T>.<>t__builder""
  IL_0164:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0169:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Call_Conditional_Struct_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    void GetName(int x);
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static async Task Main()
    {
        var item2 = new Item {Name = ""2""};
        await Call2(item2);
    }

    static async Task Call2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item?.GetName(await GetOffsetAsync(GetOffset(ref item)));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position GetName for item '-1'
";
            CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Property_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    int Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item.Position += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item.Position += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";
            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       38 (0x26)
  .maxstack  3
  .locals init (T& V_0,
                T V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_1
  IL_0004:  stloc.0
  IL_0005:  ldloc.0
  IL_0006:  ldloc.0
  IL_0007:  constrained. ""T""
  IL_000d:  callvirt   ""int IMoveable.Position.get""
  IL_0012:  ldarga.s   V_0
  IL_0014:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0019:  add
  IL_001a:  constrained. ""T""
  IL_0020:  callvirt   ""void IMoveable.Position.set""
  IL_0025:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       65 (0x41)
  .maxstack  3
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                T V_3)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldloc.0
  IL_0021:  ldloc.0
  IL_0022:  constrained. ""T""
  IL_0028:  callvirt   ""int IMoveable.Position.get""
  IL_002d:  ldarga.s   V_0
  IL_002f:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0034:  add
  IL_0035:  constrained. ""T""
  IL_003b:  callvirt   ""void IMoveable.Position.set""
  IL_0040:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Property_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    int Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item.Position += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item.Position += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       34 (0x22)
  .maxstack  3
  IL_0000:  ldarga.s   V_0
  IL_0002:  dup
  IL_0003:  constrained. ""T""
  IL_0009:  callvirt   ""int IMoveable.Position.get""
  IL_000e:  ldarga.s   V_0
  IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0015:  add
  IL_0016:  constrained. ""T""
  IL_001c:  callvirt   ""void IMoveable.Position.set""
  IL_0021:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Property_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item.Position += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item.Position += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       42 (0x2a)
  .maxstack  3
  .locals init (T& V_0,
                T V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.1
  IL_0007:  ldloca.s   V_1
  IL_0009:  stloc.0
  IL_000a:  ldloc.0
  IL_000b:  ldloc.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int IMoveable.Position.get""
  IL_0017:  ldarg.0
  IL_0018:  call       ""int Program.GetOffset<T>(ref T)""
  IL_001d:  add
  IL_001e:  constrained. ""T""
  IL_0024:  callvirt   ""void IMoveable.Position.set""
  IL_0029:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       63 (0x3f)
  .maxstack  3
  .locals init (T& V_0,
            T V_1,
            T& V_2,
            T V_3)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_3
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.3
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_001d
  IL_0012:  ldloc.2
  IL_0013:  ldobj      ""T""
  IL_0018:  stloc.1
  IL_0019:  ldloca.s   V_1
  IL_001b:  br.s       IL_001e
  IL_001d:  ldloc.2
  IL_001e:  stloc.0
  IL_001f:  ldloc.0
  IL_0020:  ldloc.0
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""int IMoveable.Position.get""
  IL_002c:  ldarg.0
  IL_002d:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0032:  add
  IL_0033:  constrained. ""T""
  IL_0039:  callvirt   ""void IMoveable.Position.set""
  IL_003e:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Property_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item.Position += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item.Position += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       32 (0x20)
  .maxstack  3
  IL_0000:  ldarg.0
  IL_0001:  dup
  IL_0002:  constrained. ""T""
  IL_0008:  callvirt   ""int IMoveable.Position.get""
  IL_000d:  ldarg.0
  IL_000e:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0013:  add
  IL_0014:  constrained. ""T""
  IL_001a:  callvirt   ""void IMoveable.Position.set""
  IL_001f:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Property_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item.Position += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item.Position += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      235 (0xeb)
  .maxstack  3
  .locals init (int V_0,
                T& V_1,
                T V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0073
    IL_000a:  ldarg.0
    IL_000b:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  stloc.2
    IL_0011:  ldloca.s   V_2
    IL_0013:  stloc.1
    IL_0014:  ldarg.0
    IL_0015:  ldloc.1
    IL_0016:  ldobj      ""T""
    IL_001b:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0020:  ldarg.0
    IL_0021:  ldloc.1
    IL_0022:  constrained. ""T""
    IL_0028:  callvirt   ""int IMoveable.Position.get""
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0032:  ldarg.0
    IL_0033:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0038:  call       ""int Program.GetOffset<T>(ref T)""
    IL_003d:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0042:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0047:  stloc.s    V_4
    IL_0049:  ldloca.s   V_4
    IL_004b:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0050:  brtrue.s   IL_0090
    IL_0052:  ldarg.0
    IL_0053:  ldc.i4.0
    IL_0054:  dup
    IL_0055:  stloc.0
    IL_0056:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_005b:  ldarg.0
    IL_005c:  ldloc.s    V_4
    IL_005e:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0063:  ldarg.0
    IL_0064:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0069:  ldloca.s   V_4
    IL_006b:  ldarg.0
    IL_006c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0071:  leave.s    IL_00ea
    IL_0073:  ldarg.0
    IL_0074:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0079:  stloc.s    V_4
    IL_007b:  ldarg.0
    IL_007c:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0081:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0087:  ldarg.0
    IL_0088:  ldc.i4.m1
    IL_0089:  dup
    IL_008a:  stloc.0
    IL_008b:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0090:  ldloca.s   V_4
    IL_0092:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0097:  stloc.3
    IL_0098:  ldarg.0
    IL_0099:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_009e:  box        ""T""
    IL_00a3:  ldarg.0
    IL_00a4:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00a9:  ldloc.3
    IL_00aa:  add
    IL_00ab:  callvirt   ""void IMoveable.Position.set""
    IL_00b0:  ldarg.0
    IL_00b1:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b6:  initobj    ""T""
    IL_00bc:  leave.s    IL_00d7
  }
  catch System.Exception
  {
    IL_00be:  stloc.s    V_5
    IL_00c0:  ldarg.0
    IL_00c1:  ldc.i4.s   -2
    IL_00c3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c8:  ldarg.0
    IL_00c9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00ce:  ldloc.s    V_5
    IL_00d0:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d5:  leave.s    IL_00ea
  }
  IL_00d7:  ldarg.0
  IL_00d8:  ldc.i4.s   -2
  IL_00da:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00df:  ldarg.0
  IL_00e0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00e5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ea:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      298 (0x12a)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_009a
    IL_000d:  ldloca.s   V_2
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.2
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldarg.0
    IL_002a:  ldloca.s   V_2
    IL_002c:  initobj    ""T""
    IL_0032:  ldloc.2
    IL_0033:  box        ""T""
    IL_0038:  brtrue.s   IL_0042
    IL_003a:  ldarg.0
    IL_003b:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0040:  br.s       IL_0048
    IL_0042:  ldarg.0
    IL_0043:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0048:  constrained. ""T""
    IL_004e:  callvirt   ""int IMoveable.Position.get""
    IL_0053:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0058:  ldarg.0
    IL_0059:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_005e:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0063:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0068:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_006d:  stloc.3
    IL_006e:  ldloca.s   V_3
    IL_0070:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0075:  brtrue.s   IL_00b6
    IL_0077:  ldarg.0
    IL_0078:  ldc.i4.0
    IL_0079:  dup
    IL_007a:  stloc.0
    IL_007b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0080:  ldarg.0
    IL_0081:  ldloc.3
    IL_0082:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0087:  ldarg.0
    IL_0088:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_008d:  ldloca.s   V_3
    IL_008f:  ldarg.0
    IL_0090:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0095:  leave      IL_0129
    IL_009a:  ldarg.0
    IL_009b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00a0:  stloc.3
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00a7:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00ad:  ldarg.0
    IL_00ae:  ldc.i4.m1
    IL_00af:  dup
    IL_00b0:  stloc.0
    IL_00b1:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00b6:  ldloca.s   V_3
    IL_00b8:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00bd:  stloc.1
    IL_00be:  ldloca.s   V_2
    IL_00c0:  initobj    ""T""
    IL_00c6:  ldloc.2
    IL_00c7:  box        ""T""
    IL_00cc:  brtrue.s   IL_00d6
    IL_00ce:  ldarg.0
    IL_00cf:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00d4:  br.s       IL_00dc
    IL_00d6:  ldarg.0
    IL_00d7:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00dc:  ldarg.0
    IL_00dd:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00e2:  ldloc.1
    IL_00e3:  add
    IL_00e4:  constrained. ""T""
    IL_00ea:  callvirt   ""void IMoveable.Position.set""
    IL_00ef:  ldarg.0
    IL_00f0:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f5:  initobj    ""T""
    IL_00fb:  leave.s    IL_0116
  }
  catch System.Exception
  {
    IL_00fd:  stloc.s    V_4
    IL_00ff:  ldarg.0
    IL_0100:  ldc.i4.s   -2
    IL_0102:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0107:  ldarg.0
    IL_0108:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_010d:  ldloc.s    V_4
    IL_010f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0114:  leave.s    IL_0129
  }
  IL_0116:  ldarg.0
  IL_0117:  ldc.i4.s   -2
  IL_0119:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_011e:  ldarg.0
  IL_011f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0124:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0129:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Property_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item.Position += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item.Position += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      202 (0xca)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0060
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  constrained. ""T""
    IL_0017:  callvirt   ""int IMoveable.Position.get""
    IL_001c:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0021:  ldarg.0
    IL_0022:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0027:  call       ""int Program.GetOffset<T>(ref T)""
    IL_002c:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0031:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0036:  stloc.2
    IL_0037:  ldloca.s   V_2
    IL_0039:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003e:  brtrue.s   IL_007c
    IL_0040:  ldarg.0
    IL_0041:  ldc.i4.0
    IL_0042:  dup
    IL_0043:  stloc.0
    IL_0044:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0049:  ldarg.0
    IL_004a:  ldloc.2
    IL_004b:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0050:  ldarg.0
    IL_0051:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0056:  ldloca.s   V_2
    IL_0058:  ldarg.0
    IL_0059:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_005e:  leave.s    IL_00c9
    IL_0060:  ldarg.0
    IL_0061:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0066:  stloc.2
    IL_0067:  ldarg.0
    IL_0068:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006d:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0073:  ldarg.0
    IL_0074:  ldc.i4.m1
    IL_0075:  dup
    IL_0076:  stloc.0
    IL_0077:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007c:  ldloca.s   V_2
    IL_007e:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0083:  stloc.1
    IL_0084:  ldarg.0
    IL_0085:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008a:  ldarg.0
    IL_008b:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0090:  ldloc.1
    IL_0091:  add
    IL_0092:  constrained. ""T""
    IL_0098:  callvirt   ""void IMoveable.Position.set""
    IL_009d:  leave.s    IL_00b6
  }
  catch System.Exception
  {
    IL_009f:  stloc.3
    IL_00a0:  ldarg.0
    IL_00a1:  ldc.i4.s   -2
    IL_00a3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00a8:  ldarg.0
    IL_00a9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00ae:  ldloc.3
    IL_00af:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00b4:  leave.s    IL_00c9
  }
  IL_00b6:  ldarg.0
  IL_00b7:  ldc.i4.s   -2
  IL_00b9:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00be:  ldarg.0
  IL_00bf:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00c4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00c9:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Property_Class_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        await Task.Yield();
        item.Position += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item.Position += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      338 (0x152)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                T& V_3,
                T V_4,
                int V_5,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00d8
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_0151
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0074:  stloc.s    V_4
    IL_0076:  ldloca.s   V_4
    IL_0078:  stloc.3
    IL_0079:  ldarg.0
    IL_007a:  ldloc.3
    IL_007b:  ldobj      ""T""
    IL_0080:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0085:  ldarg.0
    IL_0086:  ldloc.3
    IL_0087:  constrained. ""T""
    IL_008d:  callvirt   ""int IMoveable.Position.get""
    IL_0092:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0097:  ldarg.0
    IL_0098:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_009d:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00a2:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00a7:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00ac:  stloc.s    V_6
    IL_00ae:  ldloca.s   V_6
    IL_00b0:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00b5:  brtrue.s   IL_00f5
    IL_00b7:  ldarg.0
    IL_00b8:  ldc.i4.1
    IL_00b9:  dup
    IL_00ba:  stloc.0
    IL_00bb:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c0:  ldarg.0
    IL_00c1:  ldloc.s    V_6
    IL_00c3:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00c8:  ldarg.0
    IL_00c9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00ce:  ldloca.s   V_6
    IL_00d0:  ldarg.0
    IL_00d1:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00d6:  leave.s    IL_0151
    IL_00d8:  ldarg.0
    IL_00d9:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00de:  stloc.s    V_6
    IL_00e0:  ldarg.0
    IL_00e1:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00e6:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00ec:  ldarg.0
    IL_00ed:  ldc.i4.m1
    IL_00ee:  dup
    IL_00ef:  stloc.0
    IL_00f0:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00f5:  ldloca.s   V_6
    IL_00f7:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00fc:  stloc.s    V_5
    IL_00fe:  ldarg.0
    IL_00ff:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0104:  box        ""T""
    IL_0109:  ldarg.0
    IL_010a:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_010f:  ldloc.s    V_5
    IL_0111:  add
    IL_0112:  callvirt   ""void IMoveable.Position.set""
    IL_0117:  ldarg.0
    IL_0118:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_011d:  initobj    ""T""
    IL_0123:  leave.s    IL_013e
  }
  catch System.Exception
  {
    IL_0125:  stloc.s    V_7
    IL_0127:  ldarg.0
    IL_0128:  ldc.i4.s   -2
    IL_012a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_012f:  ldarg.0
    IL_0130:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0135:  ldloc.s    V_7
    IL_0137:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_013c:  leave.s    IL_0151
  }
  IL_013e:  ldarg.0
  IL_013f:  ldc.i4.s   -2
  IL_0141:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0146:  ldarg.0
  IL_0147:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_014c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0151:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      401 (0x191)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00ff
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift2>d__2<T>)""
    IL_0046:  leave      IL_0190
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldloca.s   V_4
    IL_0070:  initobj    ""T""
    IL_0076:  ldloc.s    V_4
    IL_0078:  box        ""T""
    IL_007d:  brtrue.s   IL_008b
    IL_007f:  ldarg.0
    IL_0080:  ldarg.0
    IL_0081:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0086:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_008b:  ldarg.0
    IL_008c:  ldloca.s   V_4
    IL_008e:  initobj    ""T""
    IL_0094:  ldloc.s    V_4
    IL_0096:  box        ""T""
    IL_009b:  brtrue.s   IL_00a5
    IL_009d:  ldarg.0
    IL_009e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a3:  br.s       IL_00ab
    IL_00a5:  ldarg.0
    IL_00a6:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00ab:  constrained. ""T""
    IL_00b1:  callvirt   ""int IMoveable.Position.get""
    IL_00b6:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00bb:  ldarg.0
    IL_00bc:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00c1:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00c6:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00cb:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00d0:  stloc.s    V_5
    IL_00d2:  ldloca.s   V_5
    IL_00d4:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00d9:  brtrue.s   IL_011c
    IL_00db:  ldarg.0
    IL_00dc:  ldc.i4.1
    IL_00dd:  dup
    IL_00de:  stloc.0
    IL_00df:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00e4:  ldarg.0
    IL_00e5:  ldloc.s    V_5
    IL_00e7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00ec:  ldarg.0
    IL_00ed:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00f2:  ldloca.s   V_5
    IL_00f4:  ldarg.0
    IL_00f5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00fa:  leave      IL_0190
    IL_00ff:  ldarg.0
    IL_0100:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_0105:  stloc.s    V_5
    IL_0107:  ldarg.0
    IL_0108:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_010d:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0113:  ldarg.0
    IL_0114:  ldc.i4.m1
    IL_0115:  dup
    IL_0116:  stloc.0
    IL_0117:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_011c:  ldloca.s   V_5
    IL_011e:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0123:  stloc.3
    IL_0124:  ldloca.s   V_4
    IL_0126:  initobj    ""T""
    IL_012c:  ldloc.s    V_4
    IL_012e:  box        ""T""
    IL_0133:  brtrue.s   IL_013d
    IL_0135:  ldarg.0
    IL_0136:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_013b:  br.s       IL_0143
    IL_013d:  ldarg.0
    IL_013e:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0143:  ldarg.0
    IL_0144:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0149:  ldloc.3
    IL_014a:  add
    IL_014b:  constrained. ""T""
    IL_0151:  callvirt   ""void IMoveable.Position.set""
    IL_0156:  ldarg.0
    IL_0157:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_015c:  initobj    ""T""
    IL_0162:  leave.s    IL_017d
  }
  catch System.Exception
  {
    IL_0164:  stloc.s    V_6
    IL_0166:  ldarg.0
    IL_0167:  ldc.i4.s   -2
    IL_0169:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_016e:  ldarg.0
    IL_016f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0174:  ldloc.s    V_6
    IL_0176:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_017b:  leave.s    IL_0190
  }
  IL_017d:  ldarg.0
  IL_017e:  ldc.i4.s   -2
  IL_0180:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0185:  ldarg.0
  IL_0186:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_018b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0190:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Property_Struct_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        await Task.Yield();
        item.Position += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item.Position += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      307 (0x133)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00c6
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_0132
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldarg.0
    IL_0070:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0075:  constrained. ""T""
    IL_007b:  callvirt   ""int IMoveable.Position.get""
    IL_0080:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0085:  ldarg.0
    IL_0086:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008b:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0090:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0095:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_009a:  stloc.s    V_4
    IL_009c:  ldloca.s   V_4
    IL_009e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00a3:  brtrue.s   IL_00e3
    IL_00a5:  ldarg.0
    IL_00a6:  ldc.i4.1
    IL_00a7:  dup
    IL_00a8:  stloc.0
    IL_00a9:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ae:  ldarg.0
    IL_00af:  ldloc.s    V_4
    IL_00b1:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00b6:  ldarg.0
    IL_00b7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00bc:  ldloca.s   V_4
    IL_00be:  ldarg.0
    IL_00bf:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00c4:  leave.s    IL_0132
    IL_00c6:  ldarg.0
    IL_00c7:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00cc:  stloc.s    V_4
    IL_00ce:  ldarg.0
    IL_00cf:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00d4:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00da:  ldarg.0
    IL_00db:  ldc.i4.m1
    IL_00dc:  dup
    IL_00dd:  stloc.0
    IL_00de:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e3:  ldloca.s   V_4
    IL_00e5:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00ea:  stloc.3
    IL_00eb:  ldarg.0
    IL_00ec:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00f1:  ldarg.0
    IL_00f2:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00f7:  ldloc.3
    IL_00f8:  add
    IL_00f9:  constrained. ""T""
    IL_00ff:  callvirt   ""void IMoveable.Position.set""
    IL_0104:  leave.s    IL_011f
  }
  catch System.Exception
  {
    IL_0106:  stloc.s    V_5
    IL_0108:  ldarg.0
    IL_0109:  ldc.i4.s   -2
    IL_010b:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0110:  ldarg.0
    IL_0111:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0116:  ldloc.s    V_5
    IL_0118:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_011d:  leave.s    IL_0132
  }
  IL_011f:  ldarg.0
  IL_0120:  ldc.i4.s   -2
  IL_0122:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0127:  ldarg.0
  IL_0128:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_012d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0132:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Property_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    int? Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item.Position ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item.Position ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int? GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       49 (0x31)
  .maxstack  3
  .locals init (T& V_0,
                T V_1,
                int? V_2,
                int? V_3)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_1
  IL_0004:  stloc.0
  IL_0005:  ldloc.0
  IL_0006:  constrained. ""T""
  IL_000c:  callvirt   ""int? IMoveable.Position.get""
  IL_0011:  stloc.2
  IL_0012:  ldloca.s   V_2
  IL_0014:  call       ""bool int?.HasValue.get""
  IL_0019:  brtrue.s   IL_0030
  IL_001b:  ldloc.0
  IL_001c:  ldarga.s   V_0
  IL_001e:  call       ""int? Program.GetOffset<T>(ref T)""
  IL_0023:  dup
  IL_0024:  stloc.3
  IL_0025:  constrained. ""T""
  IL_002b:  callvirt   ""void IMoveable.Position.set""
  IL_0030:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       78 (0x4e)
  .maxstack  3
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                T V_3,
                int? V_4,
                int? V_5)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldloc.0
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""int? IMoveable.Position.get""
  IL_002c:  stloc.s    V_4
  IL_002e:  ldloca.s   V_4
  IL_0030:  call       ""bool int?.HasValue.get""
  IL_0035:  brtrue.s   IL_004d
  IL_0037:  ldloc.0
  IL_0038:  ldarga.s   V_0
  IL_003a:  call       ""int? Program.GetOffset<T>(ref T)""
  IL_003f:  dup
  IL_0040:  stloc.s    V_5
  IL_0042:  constrained. ""T""
  IL_0048:  callvirt   ""void IMoveable.Position.set""
  IL_004d:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Property_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    int? Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item.Position ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item.Position ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int? GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       47 (0x2f)
  .maxstack  3
  .locals init (T& V_0,
                int? V_1,
                int? V_2)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldloc.0
  IL_0004:  constrained. ""T""
  IL_000a:  callvirt   ""int? IMoveable.Position.get""
  IL_000f:  stloc.1
  IL_0010:  ldloca.s   V_1
  IL_0012:  call       ""bool int?.HasValue.get""
  IL_0017:  brtrue.s   IL_002e
  IL_0019:  ldloc.0
  IL_001a:  ldarga.s   V_0
  IL_001c:  call       ""int? Program.GetOffset<T>(ref T)""
  IL_0021:  dup
  IL_0022:  stloc.2
  IL_0023:  constrained. ""T""
  IL_0029:  callvirt   ""void IMoveable.Position.set""
  IL_002e:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Property_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item.Position ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item.Position ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int? GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       53 (0x35)
  .maxstack  3
  .locals init (T& V_0,
                T V_1,
                int? V_2,
                int? V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.1
  IL_0007:  ldloca.s   V_1
  IL_0009:  stloc.0
  IL_000a:  ldloc.0
  IL_000b:  constrained. ""T""
  IL_0011:  callvirt   ""int? IMoveable.Position.get""
  IL_0016:  stloc.2
  IL_0017:  ldloca.s   V_2
  IL_0019:  call       ""bool int?.HasValue.get""
  IL_001e:  brtrue.s   IL_0034
  IL_0020:  ldloc.0
  IL_0021:  ldarg.0
  IL_0022:  call       ""int? Program.GetOffset<T>(ref T)""
  IL_0027:  dup
  IL_0028:  stloc.3
  IL_0029:  constrained. ""T""
  IL_002f:  callvirt   ""void IMoveable.Position.set""
  IL_0034:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       76 (0x4c)
  .maxstack  3
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                T V_3,
                int? V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_3
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.3
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_001d
  IL_0012:  ldloc.2
  IL_0013:  ldobj      ""T""
  IL_0018:  stloc.1
  IL_0019:  ldloca.s   V_1
  IL_001b:  br.s       IL_001e
  IL_001d:  ldloc.2
  IL_001e:  stloc.0
  IL_001f:  ldloc.0
  IL_0020:  constrained. ""T""
  IL_0026:  callvirt   ""int? IMoveable.Position.get""
  IL_002b:  stloc.s    V_4
  IL_002d:  ldloca.s   V_4
  IL_002f:  call       ""bool int?.HasValue.get""
  IL_0034:  brtrue.s   IL_004b
  IL_0036:  ldloc.0
  IL_0037:  ldarg.0
  IL_0038:  call       ""int? Program.GetOffset<T>(ref T)""
  IL_003d:  dup
  IL_003e:  stloc.s    V_5
  IL_0040:  constrained. ""T""
  IL_0046:  callvirt   ""void IMoveable.Position.set""
  IL_004b:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Property_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item.Position ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item.Position ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int? GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       45 (0x2d)
  .maxstack  3
  .locals init (T& V_0,
                int? V_1,
                int? V_2)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  constrained. ""T""
  IL_0009:  callvirt   ""int? IMoveable.Position.get""
  IL_000e:  stloc.1
  IL_000f:  ldloca.s   V_1
  IL_0011:  call       ""bool int?.HasValue.get""
  IL_0016:  brtrue.s   IL_002c
  IL_0018:  ldloc.0
  IL_0019:  ldarg.0
  IL_001a:  call       ""int? Program.GetOffset<T>(ref T)""
  IL_001f:  dup
  IL_0020:  stloc.2
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""void IMoveable.Position.set""
  IL_002c:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Property_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item.Position ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item.Position ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int? GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int?> GetOffsetAsync(int? i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      240 (0xf0)
  .maxstack  3
  .locals init (int V_0,
                T& V_1,
                T V_2,
                int? V_3,
                int? V_4,
                int? V_5,
                System.Runtime.CompilerServices.TaskAwaiter<int?> V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_007a
    IL_000a:  ldarg.0
    IL_000b:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  stloc.2
    IL_0011:  ldloca.s   V_2
    IL_0013:  stloc.1
    IL_0014:  ldloc.1
    IL_0015:  constrained. ""T""
    IL_001b:  callvirt   ""int? IMoveable.Position.get""
    IL_0020:  stloc.3
    IL_0021:  ldloca.s   V_3
    IL_0023:  call       ""bool int?.HasValue.get""
    IL_0028:  brtrue     IL_00c1
    IL_002d:  ldarg.0
    IL_002e:  ldloc.1
    IL_002f:  ldobj      ""T""
    IL_0034:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_003f:  call       ""int? Program.GetOffset<T>(ref T)""
    IL_0044:  call       ""System.Threading.Tasks.Task<int?> Program.GetOffsetAsync(int?)""
    IL_0049:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int?> System.Threading.Tasks.Task<int?>.GetAwaiter()""
    IL_004e:  stloc.s    V_6
    IL_0050:  ldloca.s   V_6
    IL_0052:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int?>.IsCompleted.get""
    IL_0057:  brtrue.s   IL_0097
    IL_0059:  ldarg.0
    IL_005a:  ldc.i4.0
    IL_005b:  dup
    IL_005c:  stloc.0
    IL_005d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0062:  ldarg.0
    IL_0063:  ldloc.s    V_6
    IL_0065:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__1""
    IL_006a:  ldarg.0
    IL_006b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0070:  ldloca.s   V_6
    IL_0072:  ldarg.0
    IL_0073:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int?>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int?>, ref Program.<Shift1>d__1<T>)""
    IL_0078:  leave.s    IL_00ef
    IL_007a:  ldarg.0
    IL_007b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__1""
    IL_0080:  stloc.s    V_6
    IL_0082:  ldarg.0
    IL_0083:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__1""
    IL_0088:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int?>""
    IL_008e:  ldarg.0
    IL_008f:  ldc.i4.m1
    IL_0090:  dup
    IL_0091:  stloc.0
    IL_0092:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0097:  ldloca.s   V_6
    IL_0099:  call       ""int? System.Runtime.CompilerServices.TaskAwaiter<int?>.GetResult()""
    IL_009e:  stloc.s    V_4
    IL_00a0:  ldarg.0
    IL_00a1:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a6:  box        ""T""
    IL_00ab:  ldloc.s    V_4
    IL_00ad:  dup
    IL_00ae:  stloc.s    V_5
    IL_00b0:  callvirt   ""void IMoveable.Position.set""
    IL_00b5:  ldarg.0
    IL_00b6:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00bb:  initobj    ""T""
    IL_00c1:  leave.s    IL_00dc
  }
  catch System.Exception
  {
    IL_00c3:  stloc.s    V_7
    IL_00c5:  ldarg.0
    IL_00c6:  ldc.i4.s   -2
    IL_00c8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00cd:  ldarg.0
    IL_00ce:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00d3:  ldloc.s    V_7
    IL_00d5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00da:  leave.s    IL_00ef
  }
  IL_00dc:  ldarg.0
  IL_00dd:  ldc.i4.s   -2
  IL_00df:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00e4:  ldarg.0
  IL_00e5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00ea:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ef:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      304 (0x130)
  .maxstack  3
  .locals init (int V_0,
                int? V_1,
                T V_2,
                int? V_3,
                int? V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int?> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00a3
    IL_000d:  ldloca.s   V_2
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.2
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldloca.s   V_2
    IL_002b:  initobj    ""T""
    IL_0031:  ldloc.2
    IL_0032:  box        ""T""
    IL_0037:  brtrue.s   IL_0041
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_003f:  br.s       IL_0047
    IL_0041:  ldarg.0
    IL_0042:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0047:  constrained. ""T""
    IL_004d:  callvirt   ""int? IMoveable.Position.get""
    IL_0052:  stloc.1
    IL_0053:  ldloca.s   V_1
    IL_0055:  call       ""bool int?.HasValue.get""
    IL_005a:  brtrue     IL_00f5
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0065:  call       ""int? Program.GetOffset<T>(ref T)""
    IL_006a:  call       ""System.Threading.Tasks.Task<int?> Program.GetOffsetAsync(int?)""
    IL_006f:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int?> System.Threading.Tasks.Task<int?>.GetAwaiter()""
    IL_0074:  stloc.s    V_5
    IL_0076:  ldloca.s   V_5
    IL_0078:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int?>.IsCompleted.get""
    IL_007d:  brtrue.s   IL_00c0
    IL_007f:  ldarg.0
    IL_0080:  ldc.i4.0
    IL_0081:  dup
    IL_0082:  stloc.0
    IL_0083:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0088:  ldarg.0
    IL_0089:  ldloc.s    V_5
    IL_008b:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift2>d__2<T>.<>u__1""
    IL_0090:  ldarg.0
    IL_0091:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0096:  ldloca.s   V_5
    IL_0098:  ldarg.0
    IL_0099:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int?>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int?>, ref Program.<Shift2>d__2<T>)""
    IL_009e:  leave      IL_012f
    IL_00a3:  ldarg.0
    IL_00a4:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift2>d__2<T>.<>u__1""
    IL_00a9:  stloc.s    V_5
    IL_00ab:  ldarg.0
    IL_00ac:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift2>d__2<T>.<>u__1""
    IL_00b1:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int?>""
    IL_00b7:  ldarg.0
    IL_00b8:  ldc.i4.m1
    IL_00b9:  dup
    IL_00ba:  stloc.0
    IL_00bb:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00c0:  ldloca.s   V_5
    IL_00c2:  call       ""int? System.Runtime.CompilerServices.TaskAwaiter<int?>.GetResult()""
    IL_00c7:  stloc.3
    IL_00c8:  ldloca.s   V_2
    IL_00ca:  initobj    ""T""
    IL_00d0:  ldloc.2
    IL_00d1:  box        ""T""
    IL_00d6:  brtrue.s   IL_00e0
    IL_00d8:  ldarg.0
    IL_00d9:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00de:  br.s       IL_00e6
    IL_00e0:  ldarg.0
    IL_00e1:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00e6:  ldloc.3
    IL_00e7:  dup
    IL_00e8:  stloc.s    V_4
    IL_00ea:  constrained. ""T""
    IL_00f0:  callvirt   ""void IMoveable.Position.set""
    IL_00f5:  ldarg.0
    IL_00f6:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00fb:  initobj    ""T""
    IL_0101:  leave.s    IL_011c
  }
  catch System.Exception
  {
    IL_0103:  stloc.s    V_6
    IL_0105:  ldarg.0
    IL_0106:  ldc.i4.s   -2
    IL_0108:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_010d:  ldarg.0
    IL_010e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0113:  ldloc.s    V_6
    IL_0115:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_011a:  leave.s    IL_012f
  }
  IL_011c:  ldarg.0
  IL_011d:  ldc.i4.s   -2
  IL_011f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0124:  ldarg.0
  IL_0125:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_012a:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_012f:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Property_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item.Position ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item.Position ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int? GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int?> GetOffsetAsync(int? i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      206 (0xce)
  .maxstack  3
  .locals init (int V_0,
                int? V_1,
                int? V_2,
                int? V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int?> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0066
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  constrained. ""T""
    IL_0016:  callvirt   ""int? IMoveable.Position.get""
    IL_001b:  stloc.1
    IL_001c:  ldloca.s   V_1
    IL_001e:  call       ""bool int?.HasValue.get""
    IL_0023:  brtrue.s   IL_009f
    IL_0025:  ldarg.0
    IL_0026:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_002b:  call       ""int? Program.GetOffset<T>(ref T)""
    IL_0030:  call       ""System.Threading.Tasks.Task<int?> Program.GetOffsetAsync(int?)""
    IL_0035:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int?> System.Threading.Tasks.Task<int?>.GetAwaiter()""
    IL_003a:  stloc.s    V_4
    IL_003c:  ldloca.s   V_4
    IL_003e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int?>.IsCompleted.get""
    IL_0043:  brtrue.s   IL_0083
    IL_0045:  ldarg.0
    IL_0046:  ldc.i4.0
    IL_0047:  dup
    IL_0048:  stloc.0
    IL_0049:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_004e:  ldarg.0
    IL_004f:  ldloc.s    V_4
    IL_0051:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__1""
    IL_0056:  ldarg.0
    IL_0057:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_005c:  ldloca.s   V_4
    IL_005e:  ldarg.0
    IL_005f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int?>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int?>, ref Program.<Shift1>d__1<T>)""
    IL_0064:  leave.s    IL_00cd
    IL_0066:  ldarg.0
    IL_0067:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__1""
    IL_006c:  stloc.s    V_4
    IL_006e:  ldarg.0
    IL_006f:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__1""
    IL_0074:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int?>""
    IL_007a:  ldarg.0
    IL_007b:  ldc.i4.m1
    IL_007c:  dup
    IL_007d:  stloc.0
    IL_007e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0083:  ldloca.s   V_4
    IL_0085:  call       ""int? System.Runtime.CompilerServices.TaskAwaiter<int?>.GetResult()""
    IL_008a:  stloc.2
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0091:  ldloc.2
    IL_0092:  dup
    IL_0093:  stloc.3
    IL_0094:  constrained. ""T""
    IL_009a:  callvirt   ""void IMoveable.Position.set""
    IL_009f:  leave.s    IL_00ba
  }
  catch System.Exception
  {
    IL_00a1:  stloc.s    V_5
    IL_00a3:  ldarg.0
    IL_00a4:  ldc.i4.s   -2
    IL_00a6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ab:  ldarg.0
    IL_00ac:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00b1:  ldloc.s    V_5
    IL_00b3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00b8:  leave.s    IL_00cd
  }
  IL_00ba:  ldarg.0
  IL_00bb:  ldc.i4.s   -2
  IL_00bd:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00c2:  ldarg.0
  IL_00c3:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00c8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00cd:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Property_Class_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        await Task.Yield();
        item.Position ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item.Position ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int? GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int?> GetOffsetAsync(int? i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      342 (0x156)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                T& V_3,
                T V_4,
                int? V_5,
                int? V_6,
                int? V_7,
                System.Runtime.CompilerServices.TaskAwaiter<int?> V_8,
                System.Exception V_9)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00e0
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_0155
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0074:  stloc.s    V_4
    IL_0076:  ldloca.s   V_4
    IL_0078:  stloc.3
    IL_0079:  ldloc.3
    IL_007a:  constrained. ""T""
    IL_0080:  callvirt   ""int? IMoveable.Position.get""
    IL_0085:  stloc.s    V_5
    IL_0087:  ldloca.s   V_5
    IL_0089:  call       ""bool int?.HasValue.get""
    IL_008e:  brtrue     IL_0127
    IL_0093:  ldarg.0
    IL_0094:  ldloc.3
    IL_0095:  ldobj      ""T""
    IL_009a:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_009f:  ldarg.0
    IL_00a0:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00a5:  call       ""int? Program.GetOffset<T>(ref T)""
    IL_00aa:  call       ""System.Threading.Tasks.Task<int?> Program.GetOffsetAsync(int?)""
    IL_00af:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int?> System.Threading.Tasks.Task<int?>.GetAwaiter()""
    IL_00b4:  stloc.s    V_8
    IL_00b6:  ldloca.s   V_8
    IL_00b8:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int?>.IsCompleted.get""
    IL_00bd:  brtrue.s   IL_00fd
    IL_00bf:  ldarg.0
    IL_00c0:  ldc.i4.1
    IL_00c1:  dup
    IL_00c2:  stloc.0
    IL_00c3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c8:  ldarg.0
    IL_00c9:  ldloc.s    V_8
    IL_00cb:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__2""
    IL_00d0:  ldarg.0
    IL_00d1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00d6:  ldloca.s   V_8
    IL_00d8:  ldarg.0
    IL_00d9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int?>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int?>, ref Program.<Shift1>d__1<T>)""
    IL_00de:  leave.s    IL_0155
    IL_00e0:  ldarg.0
    IL_00e1:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__2""
    IL_00e6:  stloc.s    V_8
    IL_00e8:  ldarg.0
    IL_00e9:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__2""
    IL_00ee:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int?>""
    IL_00f4:  ldarg.0
    IL_00f5:  ldc.i4.m1
    IL_00f6:  dup
    IL_00f7:  stloc.0
    IL_00f8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00fd:  ldloca.s   V_8
    IL_00ff:  call       ""int? System.Runtime.CompilerServices.TaskAwaiter<int?>.GetResult()""
    IL_0104:  stloc.s    V_6
    IL_0106:  ldarg.0
    IL_0107:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_010c:  box        ""T""
    IL_0111:  ldloc.s    V_6
    IL_0113:  dup
    IL_0114:  stloc.s    V_7
    IL_0116:  callvirt   ""void IMoveable.Position.set""
    IL_011b:  ldarg.0
    IL_011c:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0121:  initobj    ""T""
    IL_0127:  leave.s    IL_0142
  }
  catch System.Exception
  {
    IL_0129:  stloc.s    V_9
    IL_012b:  ldarg.0
    IL_012c:  ldc.i4.s   -2
    IL_012e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0133:  ldarg.0
    IL_0134:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0139:  ldloc.s    V_9
    IL_013b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0140:  leave.s    IL_0155
  }
  IL_0142:  ldarg.0
  IL_0143:  ldc.i4.s   -2
  IL_0145:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_014a:  ldarg.0
  IL_014b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0150:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0155:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      406 (0x196)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int? V_3,
                T V_4,
                int? V_5,
                int? V_6,
                System.Runtime.CompilerServices.TaskAwaiter<int?> V_7,
                System.Exception V_8)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_0106
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift2>d__2<T>)""
    IL_0046:  leave      IL_0195
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldloca.s   V_4
    IL_0070:  initobj    ""T""
    IL_0076:  ldloc.s    V_4
    IL_0078:  box        ""T""
    IL_007d:  brtrue.s   IL_008b
    IL_007f:  ldarg.0
    IL_0080:  ldarg.0
    IL_0081:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0086:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_008b:  ldloca.s   V_4
    IL_008d:  initobj    ""T""
    IL_0093:  ldloc.s    V_4
    IL_0095:  box        ""T""
    IL_009a:  brtrue.s   IL_00a4
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a2:  br.s       IL_00aa
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00aa:  constrained. ""T""
    IL_00b0:  callvirt   ""int? IMoveable.Position.get""
    IL_00b5:  stloc.3
    IL_00b6:  ldloca.s   V_3
    IL_00b8:  call       ""bool int?.HasValue.get""
    IL_00bd:  brtrue     IL_015b
    IL_00c2:  ldarg.0
    IL_00c3:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00c8:  call       ""int? Program.GetOffset<T>(ref T)""
    IL_00cd:  call       ""System.Threading.Tasks.Task<int?> Program.GetOffsetAsync(int?)""
    IL_00d2:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int?> System.Threading.Tasks.Task<int?>.GetAwaiter()""
    IL_00d7:  stloc.s    V_7
    IL_00d9:  ldloca.s   V_7
    IL_00db:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int?>.IsCompleted.get""
    IL_00e0:  brtrue.s   IL_0123
    IL_00e2:  ldarg.0
    IL_00e3:  ldc.i4.1
    IL_00e4:  dup
    IL_00e5:  stloc.0
    IL_00e6:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00eb:  ldarg.0
    IL_00ec:  ldloc.s    V_7
    IL_00ee:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift2>d__2<T>.<>u__2""
    IL_00f3:  ldarg.0
    IL_00f4:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00f9:  ldloca.s   V_7
    IL_00fb:  ldarg.0
    IL_00fc:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int?>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int?>, ref Program.<Shift2>d__2<T>)""
    IL_0101:  leave      IL_0195
    IL_0106:  ldarg.0
    IL_0107:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift2>d__2<T>.<>u__2""
    IL_010c:  stloc.s    V_7
    IL_010e:  ldarg.0
    IL_010f:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift2>d__2<T>.<>u__2""
    IL_0114:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int?>""
    IL_011a:  ldarg.0
    IL_011b:  ldc.i4.m1
    IL_011c:  dup
    IL_011d:  stloc.0
    IL_011e:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0123:  ldloca.s   V_7
    IL_0125:  call       ""int? System.Runtime.CompilerServices.TaskAwaiter<int?>.GetResult()""
    IL_012a:  stloc.s    V_5
    IL_012c:  ldloca.s   V_4
    IL_012e:  initobj    ""T""
    IL_0134:  ldloc.s    V_4
    IL_0136:  box        ""T""
    IL_013b:  brtrue.s   IL_0145
    IL_013d:  ldarg.0
    IL_013e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0143:  br.s       IL_014b
    IL_0145:  ldarg.0
    IL_0146:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_014b:  ldloc.s    V_5
    IL_014d:  dup
    IL_014e:  stloc.s    V_6
    IL_0150:  constrained. ""T""
    IL_0156:  callvirt   ""void IMoveable.Position.set""
    IL_015b:  ldarg.0
    IL_015c:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0161:  initobj    ""T""
    IL_0167:  leave.s    IL_0182
  }
  catch System.Exception
  {
    IL_0169:  stloc.s    V_8
    IL_016b:  ldarg.0
    IL_016c:  ldc.i4.s   -2
    IL_016e:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0173:  ldarg.0
    IL_0174:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0179:  ldloc.s    V_8
    IL_017b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0180:  leave.s    IL_0195
  }
  IL_0182:  ldarg.0
  IL_0183:  ldc.i4.s   -2
  IL_0185:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_018a:  ldarg.0
  IL_018b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0190:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0195:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Property_Struct_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        await Task.Yield();
        item.Position ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item.Position ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int? GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int?> GetOffsetAsync(int? i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      309 (0x135)
  .maxstack  3
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int? V_3,
                int? V_4,
                int? V_5,
                System.Runtime.CompilerServices.TaskAwaiter<int?> V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00ca
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_0134
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0074:  constrained. ""T""
    IL_007a:  callvirt   ""int? IMoveable.Position.get""
    IL_007f:  stloc.3
    IL_0080:  ldloca.s   V_3
    IL_0082:  call       ""bool int?.HasValue.get""
    IL_0087:  brtrue.s   IL_0106
    IL_0089:  ldarg.0
    IL_008a:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008f:  call       ""int? Program.GetOffset<T>(ref T)""
    IL_0094:  call       ""System.Threading.Tasks.Task<int?> Program.GetOffsetAsync(int?)""
    IL_0099:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int?> System.Threading.Tasks.Task<int?>.GetAwaiter()""
    IL_009e:  stloc.s    V_6
    IL_00a0:  ldloca.s   V_6
    IL_00a2:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int?>.IsCompleted.get""
    IL_00a7:  brtrue.s   IL_00e7
    IL_00a9:  ldarg.0
    IL_00aa:  ldc.i4.1
    IL_00ab:  dup
    IL_00ac:  stloc.0
    IL_00ad:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b2:  ldarg.0
    IL_00b3:  ldloc.s    V_6
    IL_00b5:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__2""
    IL_00ba:  ldarg.0
    IL_00bb:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00c0:  ldloca.s   V_6
    IL_00c2:  ldarg.0
    IL_00c3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int?>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int?>, ref Program.<Shift1>d__1<T>)""
    IL_00c8:  leave.s    IL_0134
    IL_00ca:  ldarg.0
    IL_00cb:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__2""
    IL_00d0:  stloc.s    V_6
    IL_00d2:  ldarg.0
    IL_00d3:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int?> Program.<Shift1>d__1<T>.<>u__2""
    IL_00d8:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int?>""
    IL_00de:  ldarg.0
    IL_00df:  ldc.i4.m1
    IL_00e0:  dup
    IL_00e1:  stloc.0
    IL_00e2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e7:  ldloca.s   V_6
    IL_00e9:  call       ""int? System.Runtime.CompilerServices.TaskAwaiter<int?>.GetResult()""
    IL_00ee:  stloc.s    V_4
    IL_00f0:  ldarg.0
    IL_00f1:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00f6:  ldloc.s    V_4
    IL_00f8:  dup
    IL_00f9:  stloc.s    V_5
    IL_00fb:  constrained. ""T""
    IL_0101:  callvirt   ""void IMoveable.Position.set""
    IL_0106:  leave.s    IL_0121
  }
  catch System.Exception
  {
    IL_0108:  stloc.s    V_7
    IL_010a:  ldarg.0
    IL_010b:  ldc.i4.s   -2
    IL_010d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0112:  ldarg.0
    IL_0113:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0118:  ldloc.s    V_7
    IL_011a:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_011f:  leave.s    IL_0134
  }
  IL_0121:  ldarg.0
  IL_0122:  ldc.i4.s   -2
  IL_0124:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0129:  ldarg.0
  IL_012a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_012f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0134:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Index()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       42 (0x2a)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_1
  IL_0004:  stloc.0
  IL_0005:  ldarga.s   V_0
  IL_0007:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000c:  stloc.2
  IL_000d:  ldloc.0
  IL_000e:  ldloc.2
  IL_000f:  ldloc.0
  IL_0010:  ldloc.2
  IL_0011:  constrained. ""T""
  IL_0017:  callvirt   ""int IMoveable.this[int].get""
  IL_001c:  ldc.i4.1
  IL_001d:  add
  IL_001e:  constrained. ""T""
  IL_0024:  callvirt   ""void IMoveable.this[int].set""
  IL_0029:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       70 (0x46)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_4
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_4
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  ldloc.3
  IL_002b:  ldloc.0
  IL_002c:  ldloc.3
  IL_002d:  constrained. ""T""
  IL_0033:  callvirt   ""int IMoveable.this[int].get""
  IL_0038:  ldc.i4.1
  IL_0039:  add
  IL_003a:  constrained. ""T""
  IL_0040:  callvirt   ""void IMoveable.this[int].set""
  IL_0045:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Index()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       40 (0x28)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  ldloc.1
  IL_000d:  ldloc.0
  IL_000e:  ldloc.1
  IL_000f:  constrained. ""T""
  IL_0015:  callvirt   ""int IMoveable.this[int].get""
  IL_001a:  ldc.i4.1
  IL_001b:  add
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""void IMoveable.this[int].set""
  IL_0027:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Index_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       46 (0x2e)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.1
  IL_0007:  ldloca.s   V_1
  IL_0009:  stloc.0
  IL_000a:  ldarg.0
  IL_000b:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0010:  stloc.2
  IL_0011:  ldloc.0
  IL_0012:  ldloc.2
  IL_0013:  ldloc.0
  IL_0014:  ldloc.2
  IL_0015:  constrained. ""T""
  IL_001b:  callvirt   ""int IMoveable.this[int].get""
  IL_0020:  ldc.i4.1
  IL_0021:  add
  IL_0022:  constrained. ""T""
  IL_0028:  callvirt   ""void IMoveable.this[int].set""
  IL_002d:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       68 (0x44)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_4
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_4
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  ldloc.3
  IL_0029:  ldloc.0
  IL_002a:  ldloc.3
  IL_002b:  constrained. ""T""
  IL_0031:  callvirt   ""int IMoveable.this[int].get""
  IL_0036:  ldc.i4.1
  IL_0037:  add
  IL_0038:  constrained. ""T""
  IL_003e:  callvirt   ""void IMoveable.this[int].set""
  IL_0043:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Index_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       38 (0x26)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  ldloc.1
  IL_000b:  ldloc.0
  IL_000c:  ldloc.1
  IL_000d:  constrained. ""T""
  IL_0013:  callvirt   ""int IMoveable.this[int].get""
  IL_0018:  ldc.i4.1
  IL_0019:  add
  IL_001a:  constrained. ""T""
  IL_0020:  callvirt   ""void IMoveable.this[int].set""
  IL_0025:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Index_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      217 (0xd9)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0058
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.2
    IL_002c:  ldloca.s   V_2
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0074
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.2
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_2
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0053:  leave      IL_00d8
    IL_0058:  ldarg.0
    IL_0059:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005e:  stloc.2
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0065:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006b:  ldarg.0
    IL_006c:  ldc.i4.m1
    IL_006d:  dup
    IL_006e:  stloc.0
    IL_006f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0074:  ldloca.s   V_2
    IL_0076:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007b:  stloc.1
    IL_007c:  ldarg.0
    IL_007d:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0082:  box        ""T""
    IL_0087:  ldloc.1
    IL_0088:  ldarg.0
    IL_0089:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008e:  box        ""T""
    IL_0093:  ldloc.1
    IL_0094:  callvirt   ""int IMoveable.this[int].get""
    IL_0099:  ldc.i4.1
    IL_009a:  add
    IL_009b:  callvirt   ""void IMoveable.this[int].set""
    IL_00a0:  ldarg.0
    IL_00a1:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a6:  initobj    ""T""
    IL_00ac:  leave.s    IL_00c5
  }
  catch System.Exception
  {
    IL_00ae:  stloc.3
    IL_00af:  ldarg.0
    IL_00b0:  ldc.i4.s   -2
    IL_00b2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b7:  ldarg.0
    IL_00b8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00bd:  ldloc.3
    IL_00be:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00c3:  leave.s    IL_00d8
  }
  IL_00c5:  ldarg.0
  IL_00c6:  ldc.i4.s   -2
  IL_00c8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00cd:  ldarg.0
  IL_00ce:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00d3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00d8:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      285 (0x11d)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0068
    IL_000a:  ldloca.s   V_2
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.2
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.3
    IL_003c:  ldloca.s   V_3
    IL_003e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0043:  brtrue.s   IL_0084
    IL_0045:  ldarg.0
    IL_0046:  ldc.i4.0
    IL_0047:  dup
    IL_0048:  stloc.0
    IL_0049:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_004e:  ldarg.0
    IL_004f:  ldloc.3
    IL_0050:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005b:  ldloca.s   V_3
    IL_005d:  ldarg.0
    IL_005e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0063:  leave      IL_011c
    IL_0068:  ldarg.0
    IL_0069:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_006e:  stloc.3
    IL_006f:  ldarg.0
    IL_0070:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0075:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007b:  ldarg.0
    IL_007c:  ldc.i4.m1
    IL_007d:  dup
    IL_007e:  stloc.0
    IL_007f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0084:  ldloca.s   V_3
    IL_0086:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008b:  stloc.1
    IL_008c:  ldloca.s   V_2
    IL_008e:  initobj    ""T""
    IL_0094:  ldloc.2
    IL_0095:  box        ""T""
    IL_009a:  brtrue.s   IL_00a4
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a2:  br.s       IL_00aa
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00aa:  ldloc.1
    IL_00ab:  ldloca.s   V_2
    IL_00ad:  initobj    ""T""
    IL_00b3:  ldloc.2
    IL_00b4:  box        ""T""
    IL_00b9:  brtrue.s   IL_00c3
    IL_00bb:  ldarg.0
    IL_00bc:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00c1:  br.s       IL_00c9
    IL_00c3:  ldarg.0
    IL_00c4:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00c9:  ldloc.1
    IL_00ca:  constrained. ""T""
    IL_00d0:  callvirt   ""int IMoveable.this[int].get""
    IL_00d5:  ldc.i4.1
    IL_00d6:  add
    IL_00d7:  constrained. ""T""
    IL_00dd:  callvirt   ""void IMoveable.this[int].set""
    IL_00e2:  ldarg.0
    IL_00e3:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00e8:  initobj    ""T""
    IL_00ee:  leave.s    IL_0109
  }
  catch System.Exception
  {
    IL_00f0:  stloc.s    V_4
    IL_00f2:  ldarg.0
    IL_00f3:  ldc.i4.s   -2
    IL_00f5:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00fa:  ldarg.0
    IL_00fb:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0100:  ldloc.s    V_4
    IL_0102:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0107:  leave.s    IL_011c
  }
  IL_0109:  ldarg.0
  IL_010a:  ldc.i4.s   -2
  IL_010c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0111:  ldarg.0
  IL_0112:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0117:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_011c:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Index_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      192 (0xc0)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0049
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.2
    IL_0020:  ldloca.s   V_2
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0065
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.2
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_2
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0047:  leave.s    IL_00bf
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004f:  stloc.2
    IL_0050:  ldarg.0
    IL_0051:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0056:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005c:  ldarg.0
    IL_005d:  ldc.i4.m1
    IL_005e:  dup
    IL_005f:  stloc.0
    IL_0060:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0065:  ldloca.s   V_2
    IL_0067:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006c:  stloc.1
    IL_006d:  ldarg.0
    IL_006e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0073:  ldloc.1
    IL_0074:  ldarg.0
    IL_0075:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_007a:  ldloc.1
    IL_007b:  constrained. ""T""
    IL_0081:  callvirt   ""int IMoveable.this[int].get""
    IL_0086:  ldc.i4.1
    IL_0087:  add
    IL_0088:  constrained. ""T""
    IL_008e:  callvirt   ""void IMoveable.this[int].set""
    IL_0093:  leave.s    IL_00ac
  }
  catch System.Exception
  {
    IL_0095:  stloc.3
    IL_0096:  ldarg.0
    IL_0097:  ldc.i4.s   -2
    IL_0099:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_009e:  ldarg.0
    IL_009f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00a4:  ldloc.3
    IL_00a5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00aa:  leave.s    IL_00bf
  }
  IL_00ac:  ldarg.0
  IL_00ad:  ldc.i4.s   -2
  IL_00af:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00b4:  ldarg.0
  IL_00b5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00ba:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00bf:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Index_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] += 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      322 (0x142)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00be
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_0141
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldarg.0
    IL_0070:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0075:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_007a:  ldarg.0
    IL_007b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0080:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0085:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_008a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_008f:  stloc.s    V_4
    IL_0091:  ldloca.s   V_4
    IL_0093:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0098:  brtrue.s   IL_00db
    IL_009a:  ldarg.0
    IL_009b:  ldc.i4.1
    IL_009c:  dup
    IL_009d:  stloc.0
    IL_009e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00a3:  ldarg.0
    IL_00a4:  ldloc.s    V_4
    IL_00a6:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00ab:  ldarg.0
    IL_00ac:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00b1:  ldloca.s   V_4
    IL_00b3:  ldarg.0
    IL_00b4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00b9:  leave      IL_0141
    IL_00be:  ldarg.0
    IL_00bf:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00c4:  stloc.s    V_4
    IL_00c6:  ldarg.0
    IL_00c7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00cc:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00d2:  ldarg.0
    IL_00d3:  ldc.i4.m1
    IL_00d4:  dup
    IL_00d5:  stloc.0
    IL_00d6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00db:  ldloca.s   V_4
    IL_00dd:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00e2:  stloc.3
    IL_00e3:  ldarg.0
    IL_00e4:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00e9:  box        ""T""
    IL_00ee:  ldloc.3
    IL_00ef:  ldarg.0
    IL_00f0:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00f5:  box        ""T""
    IL_00fa:  ldloc.3
    IL_00fb:  callvirt   ""int IMoveable.this[int].get""
    IL_0100:  ldc.i4.1
    IL_0101:  add
    IL_0102:  callvirt   ""void IMoveable.this[int].set""
    IL_0107:  ldarg.0
    IL_0108:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_010d:  initobj    ""T""
    IL_0113:  leave.s    IL_012e
  }
  catch System.Exception
  {
    IL_0115:  stloc.s    V_5
    IL_0117:  ldarg.0
    IL_0118:  ldc.i4.s   -2
    IL_011a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_011f:  ldarg.0
    IL_0120:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0125:  ldloc.s    V_5
    IL_0127:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_012c:  leave.s    IL_0141
  }
  IL_012e:  ldarg.0
  IL_012f:  ldc.i4.s   -2
  IL_0131:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0136:  ldarg.0
  IL_0137:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_013c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0141:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      391 (0x187)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00cf
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift2>d__2<T>)""
    IL_0046:  leave      IL_0186
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldloca.s   V_4
    IL_0070:  initobj    ""T""
    IL_0076:  ldloc.s    V_4
    IL_0078:  box        ""T""
    IL_007d:  brtrue.s   IL_008b
    IL_007f:  ldarg.0
    IL_0080:  ldarg.0
    IL_0081:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0086:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0091:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0096:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_009b:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00a0:  stloc.s    V_5
    IL_00a2:  ldloca.s   V_5
    IL_00a4:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00a9:  brtrue.s   IL_00ec
    IL_00ab:  ldarg.0
    IL_00ac:  ldc.i4.1
    IL_00ad:  dup
    IL_00ae:  stloc.0
    IL_00af:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00b4:  ldarg.0
    IL_00b5:  ldloc.s    V_5
    IL_00b7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00bc:  ldarg.0
    IL_00bd:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00c2:  ldloca.s   V_5
    IL_00c4:  ldarg.0
    IL_00c5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00ca:  leave      IL_0186
    IL_00cf:  ldarg.0
    IL_00d0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00d5:  stloc.s    V_5
    IL_00d7:  ldarg.0
    IL_00d8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00dd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00e3:  ldarg.0
    IL_00e4:  ldc.i4.m1
    IL_00e5:  dup
    IL_00e6:  stloc.0
    IL_00e7:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00ec:  ldloca.s   V_5
    IL_00ee:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00f3:  stloc.3
    IL_00f4:  ldloca.s   V_4
    IL_00f6:  initobj    ""T""
    IL_00fc:  ldloc.s    V_4
    IL_00fe:  box        ""T""
    IL_0103:  brtrue.s   IL_010d
    IL_0105:  ldarg.0
    IL_0106:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_010b:  br.s       IL_0113
    IL_010d:  ldarg.0
    IL_010e:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0113:  ldloc.3
    IL_0114:  ldloca.s   V_4
    IL_0116:  initobj    ""T""
    IL_011c:  ldloc.s    V_4
    IL_011e:  box        ""T""
    IL_0123:  brtrue.s   IL_012d
    IL_0125:  ldarg.0
    IL_0126:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_012b:  br.s       IL_0133
    IL_012d:  ldarg.0
    IL_012e:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0133:  ldloc.3
    IL_0134:  constrained. ""T""
    IL_013a:  callvirt   ""int IMoveable.this[int].get""
    IL_013f:  ldc.i4.1
    IL_0140:  add
    IL_0141:  constrained. ""T""
    IL_0147:  callvirt   ""void IMoveable.this[int].set""
    IL_014c:  ldarg.0
    IL_014d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0152:  initobj    ""T""
    IL_0158:  leave.s    IL_0173
  }
  catch System.Exception
  {
    IL_015a:  stloc.s    V_6
    IL_015c:  ldarg.0
    IL_015d:  ldc.i4.s   -2
    IL_015f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0164:  ldarg.0
    IL_0165:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_016a:  ldloc.s    V_6
    IL_016c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0171:  leave.s    IL_0186
  }
  IL_0173:  ldarg.0
  IL_0174:  ldc.i4.s   -2
  IL_0176:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_017b:  ldarg.0
  IL_017c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0181:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0186:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Index_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] += 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      297 (0x129)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00af
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_0128
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0074:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0079:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_007e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0083:  stloc.s    V_4
    IL_0085:  ldloca.s   V_4
    IL_0087:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_008c:  brtrue.s   IL_00cc
    IL_008e:  ldarg.0
    IL_008f:  ldc.i4.1
    IL_0090:  dup
    IL_0091:  stloc.0
    IL_0092:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0097:  ldarg.0
    IL_0098:  ldloc.s    V_4
    IL_009a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_009f:  ldarg.0
    IL_00a0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00a5:  ldloca.s   V_4
    IL_00a7:  ldarg.0
    IL_00a8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00ad:  leave.s    IL_0128
    IL_00af:  ldarg.0
    IL_00b0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00b5:  stloc.s    V_4
    IL_00b7:  ldarg.0
    IL_00b8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00bd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00c3:  ldarg.0
    IL_00c4:  ldc.i4.m1
    IL_00c5:  dup
    IL_00c6:  stloc.0
    IL_00c7:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00cc:  ldloca.s   V_4
    IL_00ce:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00d3:  stloc.3
    IL_00d4:  ldarg.0
    IL_00d5:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00da:  ldloc.3
    IL_00db:  ldarg.0
    IL_00dc:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00e1:  ldloc.3
    IL_00e2:  constrained. ""T""
    IL_00e8:  callvirt   ""int IMoveable.this[int].get""
    IL_00ed:  ldc.i4.1
    IL_00ee:  add
    IL_00ef:  constrained. ""T""
    IL_00f5:  callvirt   ""void IMoveable.this[int].set""
    IL_00fa:  leave.s    IL_0115
  }
  catch System.Exception
  {
    IL_00fc:  stloc.s    V_5
    IL_00fe:  ldarg.0
    IL_00ff:  ldc.i4.s   -2
    IL_0101:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0106:  ldarg.0
    IL_0107:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_010c:  ldloc.s    V_5
    IL_010e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0113:  leave.s    IL_0128
  }
  IL_0115:  ldarg.0
  IL_0116:  ldc.i4.s   -2
  IL_0118:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_011d:  ldarg.0
  IL_011e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0123:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0128:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] ++;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       42 (0x2a)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloca.s   V_0
  IL_0004:  ldarga.s   V_0
  IL_0006:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000b:  stloc.1
  IL_000c:  dup
  IL_000d:  ldloc.1
  IL_000e:  constrained. ""T""
  IL_0014:  callvirt   ""int IMoveable.this[int].get""
  IL_0019:  stloc.2
  IL_001a:  ldloc.1
  IL_001b:  ldloc.2
  IL_001c:  ldc.i4.1
  IL_001d:  add
  IL_001e:  constrained. ""T""
  IL_0024:  callvirt   ""void IMoveable.this[int].set""
  IL_0029:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       70 (0x46)
  .maxstack  4
  .locals init (T V_0,
                T& V_1,
                int V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.1
  IL_0003:  ldloca.s   V_4
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_4
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.1
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.0
  IL_001b:  ldloca.s   V_0
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.1
  IL_0020:  ldarga.s   V_0
  IL_0022:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0027:  stloc.2
  IL_0028:  dup
  IL_0029:  ldloc.2
  IL_002a:  constrained. ""T""
  IL_0030:  callvirt   ""int IMoveable.this[int].get""
  IL_0035:  stloc.3
  IL_0036:  ldloc.2
  IL_0037:  ldloc.3
  IL_0038:  ldc.i4.1
  IL_0039:  add
  IL_003a:  constrained. ""T""
  IL_0040:  callvirt   ""void IMoveable.this[int].set""
  IL_0045:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] ++;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       40 (0x28)
  .maxstack  4
  .locals init (int V_0,
                int V_1)
  IL_0000:  ldarga.s   V_0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.0
  IL_000a:  dup
  IL_000b:  ldloc.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int IMoveable.this[int].get""
  IL_0017:  stloc.1
  IL_0018:  ldloc.0
  IL_0019:  ldloc.1
  IL_001a:  ldc.i4.1
  IL_001b:  add
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""void IMoveable.this[int].set""
  IL_0027:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] ++;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       46 (0x2e)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldloca.s   V_0
  IL_0009:  ldarg.0
  IL_000a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000f:  stloc.1
  IL_0010:  dup
  IL_0011:  ldloc.1
  IL_0012:  constrained. ""T""
  IL_0018:  callvirt   ""int IMoveable.this[int].get""
  IL_001d:  stloc.2
  IL_001e:  ldloc.1
  IL_001f:  ldloc.2
  IL_0020:  ldc.i4.1
  IL_0021:  add
  IL_0022:  constrained. ""T""
  IL_0028:  callvirt   ""void IMoveable.this[int].set""
  IL_002d:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       68 (0x44)
  .maxstack  4
  .locals init (T V_0,
                T& V_1,
                int V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_4
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_4
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.1
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.0
  IL_001a:  ldloca.s   V_0
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.1
  IL_001f:  ldarg.0
  IL_0020:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0025:  stloc.2
  IL_0026:  dup
  IL_0027:  ldloc.2
  IL_0028:  constrained. ""T""
  IL_002e:  callvirt   ""int IMoveable.this[int].get""
  IL_0033:  stloc.3
  IL_0034:  ldloc.2
  IL_0035:  ldloc.3
  IL_0036:  ldc.i4.1
  IL_0037:  add
  IL_0038:  constrained. ""T""
  IL_003e:  callvirt   ""void IMoveable.this[int].set""
  IL_0043:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] ++;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       38 (0x26)
  .maxstack  4
  .locals init (int V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldarg.0
  IL_0002:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0007:  stloc.0
  IL_0008:  dup
  IL_0009:  ldloc.0
  IL_000a:  constrained. ""T""
  IL_0010:  callvirt   ""int IMoveable.this[int].get""
  IL_0015:  stloc.1
  IL_0016:  ldloc.0
  IL_0017:  ldloc.1
  IL_0018:  ldc.i4.1
  IL_0019:  add
  IL_001a:  constrained. ""T""
  IL_0020:  callvirt   ""void IMoveable.this[int].set""
  IL_0025:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ++;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      221 (0xdd)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0058
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.3
    IL_002c:  ldloca.s   V_3
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0074
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.3
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_3
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0053:  leave      IL_00dc
    IL_0058:  ldarg.0
    IL_0059:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005e:  stloc.3
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0065:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006b:  ldarg.0
    IL_006c:  ldc.i4.m1
    IL_006d:  dup
    IL_006e:  stloc.0
    IL_006f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0074:  ldloca.s   V_3
    IL_0076:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007b:  stloc.1
    IL_007c:  ldarg.0
    IL_007d:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0082:  box        ""T""
    IL_0087:  ldloc.1
    IL_0088:  callvirt   ""int IMoveable.this[int].get""
    IL_008d:  stloc.2
    IL_008e:  ldarg.0
    IL_008f:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0094:  box        ""T""
    IL_0099:  ldloc.1
    IL_009a:  ldloc.2
    IL_009b:  ldc.i4.1
    IL_009c:  add
    IL_009d:  callvirt   ""void IMoveable.this[int].set""
    IL_00a2:  ldarg.0
    IL_00a3:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a8:  initobj    ""T""
    IL_00ae:  leave.s    IL_00c9
  }
  catch System.Exception
  {
    IL_00b0:  stloc.s    V_4
    IL_00b2:  ldarg.0
    IL_00b3:  ldc.i4.s   -2
    IL_00b5:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ba:  ldarg.0
    IL_00bb:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00c0:  ldloc.s    V_4
    IL_00c2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00c7:  leave.s    IL_00dc
  }
  IL_00c9:  ldarg.0
  IL_00ca:  ldc.i4.s   -2
  IL_00cc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00d1:  ldarg.0
  IL_00d2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00d7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00dc:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      290 (0x122)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006a
    IL_000a:  ldloca.s   V_3
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.3
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.s    V_4
    IL_003d:  ldloca.s   V_4
    IL_003f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0044:  brtrue.s   IL_0087
    IL_0046:  ldarg.0
    IL_0047:  ldc.i4.0
    IL_0048:  dup
    IL_0049:  stloc.0
    IL_004a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_004f:  ldarg.0
    IL_0050:  ldloc.s    V_4
    IL_0052:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0057:  ldarg.0
    IL_0058:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005d:  ldloca.s   V_4
    IL_005f:  ldarg.0
    IL_0060:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0065:  leave      IL_0121
    IL_006a:  ldarg.0
    IL_006b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0070:  stloc.s    V_4
    IL_0072:  ldarg.0
    IL_0073:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0078:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007e:  ldarg.0
    IL_007f:  ldc.i4.m1
    IL_0080:  dup
    IL_0081:  stloc.0
    IL_0082:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0087:  ldloca.s   V_4
    IL_0089:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008e:  stloc.1
    IL_008f:  ldloca.s   V_3
    IL_0091:  initobj    ""T""
    IL_0097:  ldloc.3
    IL_0098:  box        ""T""
    IL_009d:  brtrue.s   IL_00a7
    IL_009f:  ldarg.0
    IL_00a0:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a5:  br.s       IL_00ad
    IL_00a7:  ldarg.0
    IL_00a8:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00ad:  ldloc.1
    IL_00ae:  constrained. ""T""
    IL_00b4:  callvirt   ""int IMoveable.this[int].get""
    IL_00b9:  stloc.2
    IL_00ba:  ldloca.s   V_3
    IL_00bc:  initobj    ""T""
    IL_00c2:  ldloc.3
    IL_00c3:  box        ""T""
    IL_00c8:  brtrue.s   IL_00d2
    IL_00ca:  ldarg.0
    IL_00cb:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00d0:  br.s       IL_00d8
    IL_00d2:  ldarg.0
    IL_00d3:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00d8:  ldloc.1
    IL_00d9:  ldloc.2
    IL_00da:  ldc.i4.1
    IL_00db:  add
    IL_00dc:  constrained. ""T""
    IL_00e2:  callvirt   ""void IMoveable.this[int].set""
    IL_00e7:  ldarg.0
    IL_00e8:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00ed:  initobj    ""T""
    IL_00f3:  leave.s    IL_010e
  }
  catch System.Exception
  {
    IL_00f5:  stloc.s    V_5
    IL_00f7:  ldarg.0
    IL_00f8:  ldc.i4.s   -2
    IL_00fa:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00ff:  ldarg.0
    IL_0100:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0105:  ldloc.s    V_5
    IL_0107:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_010c:  leave.s    IL_0121
  }
  IL_010e:  ldarg.0
  IL_010f:  ldc.i4.s   -2
  IL_0111:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0116:  ldarg.0
  IL_0117:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_011c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0121:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ++;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      196 (0xc4)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0049
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.3
    IL_0020:  ldloca.s   V_3
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0065
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.3
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_3
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0047:  leave.s    IL_00c3
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004f:  stloc.3
    IL_0050:  ldarg.0
    IL_0051:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0056:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005c:  ldarg.0
    IL_005d:  ldc.i4.m1
    IL_005e:  dup
    IL_005f:  stloc.0
    IL_0060:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0065:  ldloca.s   V_3
    IL_0067:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006c:  stloc.1
    IL_006d:  ldarg.0
    IL_006e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0073:  ldloc.1
    IL_0074:  constrained. ""T""
    IL_007a:  callvirt   ""int IMoveable.this[int].get""
    IL_007f:  stloc.2
    IL_0080:  ldarg.0
    IL_0081:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0086:  ldloc.1
    IL_0087:  ldloc.2
    IL_0088:  ldc.i4.1
    IL_0089:  add
    IL_008a:  constrained. ""T""
    IL_0090:  callvirt   ""void IMoveable.this[int].set""
    IL_0095:  leave.s    IL_00b0
  }
  catch System.Exception
  {
    IL_0097:  stloc.s    V_4
    IL_0099:  ldarg.0
    IL_009a:  ldc.i4.s   -2
    IL_009c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00a7:  ldloc.s    V_4
    IL_00a9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ae:  leave.s    IL_00c3
  }
  IL_00b0:  ldarg.0
  IL_00b1:  ldc.i4.s   -2
  IL_00b3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00b8:  ldarg.0
  IL_00b9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00be:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00c3:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Class_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] ++;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      326 (0x146)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00be
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_0145
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldarg.0
    IL_0070:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0075:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_007a:  ldarg.0
    IL_007b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0080:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0085:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_008a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_008f:  stloc.s    V_5
    IL_0091:  ldloca.s   V_5
    IL_0093:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0098:  brtrue.s   IL_00db
    IL_009a:  ldarg.0
    IL_009b:  ldc.i4.1
    IL_009c:  dup
    IL_009d:  stloc.0
    IL_009e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00a3:  ldarg.0
    IL_00a4:  ldloc.s    V_5
    IL_00a6:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00ab:  ldarg.0
    IL_00ac:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00b1:  ldloca.s   V_5
    IL_00b3:  ldarg.0
    IL_00b4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00b9:  leave      IL_0145
    IL_00be:  ldarg.0
    IL_00bf:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00c4:  stloc.s    V_5
    IL_00c6:  ldarg.0
    IL_00c7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00cc:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00d2:  ldarg.0
    IL_00d3:  ldc.i4.m1
    IL_00d4:  dup
    IL_00d5:  stloc.0
    IL_00d6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00db:  ldloca.s   V_5
    IL_00dd:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00e2:  stloc.3
    IL_00e3:  ldarg.0
    IL_00e4:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00e9:  box        ""T""
    IL_00ee:  ldloc.3
    IL_00ef:  callvirt   ""int IMoveable.this[int].get""
    IL_00f4:  stloc.s    V_4
    IL_00f6:  ldarg.0
    IL_00f7:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00fc:  box        ""T""
    IL_0101:  ldloc.3
    IL_0102:  ldloc.s    V_4
    IL_0104:  ldc.i4.1
    IL_0105:  add
    IL_0106:  callvirt   ""void IMoveable.this[int].set""
    IL_010b:  ldarg.0
    IL_010c:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0111:  initobj    ""T""
    IL_0117:  leave.s    IL_0132
  }
  catch System.Exception
  {
    IL_0119:  stloc.s    V_6
    IL_011b:  ldarg.0
    IL_011c:  ldc.i4.s   -2
    IL_011e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0123:  ldarg.0
    IL_0124:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0129:  ldloc.s    V_6
    IL_012b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0130:  leave.s    IL_0145
  }
  IL_0132:  ldarg.0
  IL_0133:  ldc.i4.s   -2
  IL_0135:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_013a:  ldarg.0
  IL_013b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0140:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0145:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      395 (0x18b)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                int V_4,
                T V_5,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00cf
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift2>d__2<T>)""
    IL_0046:  leave      IL_018a
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldloca.s   V_5
    IL_0070:  initobj    ""T""
    IL_0076:  ldloc.s    V_5
    IL_0078:  box        ""T""
    IL_007d:  brtrue.s   IL_008b
    IL_007f:  ldarg.0
    IL_0080:  ldarg.0
    IL_0081:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0086:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0091:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0096:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_009b:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00a0:  stloc.s    V_6
    IL_00a2:  ldloca.s   V_6
    IL_00a4:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00a9:  brtrue.s   IL_00ec
    IL_00ab:  ldarg.0
    IL_00ac:  ldc.i4.1
    IL_00ad:  dup
    IL_00ae:  stloc.0
    IL_00af:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00b4:  ldarg.0
    IL_00b5:  ldloc.s    V_6
    IL_00b7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00bc:  ldarg.0
    IL_00bd:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00c2:  ldloca.s   V_6
    IL_00c4:  ldarg.0
    IL_00c5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00ca:  leave      IL_018a
    IL_00cf:  ldarg.0
    IL_00d0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00d5:  stloc.s    V_6
    IL_00d7:  ldarg.0
    IL_00d8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00dd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00e3:  ldarg.0
    IL_00e4:  ldc.i4.m1
    IL_00e5:  dup
    IL_00e6:  stloc.0
    IL_00e7:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00ec:  ldloca.s   V_6
    IL_00ee:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00f3:  stloc.3
    IL_00f4:  ldloca.s   V_5
    IL_00f6:  initobj    ""T""
    IL_00fc:  ldloc.s    V_5
    IL_00fe:  box        ""T""
    IL_0103:  brtrue.s   IL_010d
    IL_0105:  ldarg.0
    IL_0106:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_010b:  br.s       IL_0113
    IL_010d:  ldarg.0
    IL_010e:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0113:  ldloc.3
    IL_0114:  constrained. ""T""
    IL_011a:  callvirt   ""int IMoveable.this[int].get""
    IL_011f:  stloc.s    V_4
    IL_0121:  ldloca.s   V_5
    IL_0123:  initobj    ""T""
    IL_0129:  ldloc.s    V_5
    IL_012b:  box        ""T""
    IL_0130:  brtrue.s   IL_013a
    IL_0132:  ldarg.0
    IL_0133:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0138:  br.s       IL_0140
    IL_013a:  ldarg.0
    IL_013b:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0140:  ldloc.3
    IL_0141:  ldloc.s    V_4
    IL_0143:  ldc.i4.1
    IL_0144:  add
    IL_0145:  constrained. ""T""
    IL_014b:  callvirt   ""void IMoveable.this[int].set""
    IL_0150:  ldarg.0
    IL_0151:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0156:  initobj    ""T""
    IL_015c:  leave.s    IL_0177
  }
  catch System.Exception
  {
    IL_015e:  stloc.s    V_7
    IL_0160:  ldarg.0
    IL_0161:  ldc.i4.s   -2
    IL_0163:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0168:  ldarg.0
    IL_0169:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_016e:  ldloc.s    V_7
    IL_0170:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0175:  leave.s    IL_018a
  }
  IL_0177:  ldarg.0
  IL_0178:  ldc.i4.s   -2
  IL_017a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_017f:  ldarg.0
  IL_0180:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0185:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_018a:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Struct_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] ++;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      301 (0x12d)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00af
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_012c
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0074:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0079:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_007e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0083:  stloc.s    V_5
    IL_0085:  ldloca.s   V_5
    IL_0087:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_008c:  brtrue.s   IL_00cc
    IL_008e:  ldarg.0
    IL_008f:  ldc.i4.1
    IL_0090:  dup
    IL_0091:  stloc.0
    IL_0092:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0097:  ldarg.0
    IL_0098:  ldloc.s    V_5
    IL_009a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_009f:  ldarg.0
    IL_00a0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00a5:  ldloca.s   V_5
    IL_00a7:  ldarg.0
    IL_00a8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00ad:  leave.s    IL_012c
    IL_00af:  ldarg.0
    IL_00b0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00b5:  stloc.s    V_5
    IL_00b7:  ldarg.0
    IL_00b8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00bd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00c3:  ldarg.0
    IL_00c4:  ldc.i4.m1
    IL_00c5:  dup
    IL_00c6:  stloc.0
    IL_00c7:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00cc:  ldloca.s   V_5
    IL_00ce:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00d3:  stloc.3
    IL_00d4:  ldarg.0
    IL_00d5:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00da:  ldloc.3
    IL_00db:  constrained. ""T""
    IL_00e1:  callvirt   ""int IMoveable.this[int].get""
    IL_00e6:  stloc.s    V_4
    IL_00e8:  ldarg.0
    IL_00e9:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00ee:  ldloc.3
    IL_00ef:  ldloc.s    V_4
    IL_00f1:  ldc.i4.1
    IL_00f2:  add
    IL_00f3:  constrained. ""T""
    IL_00f9:  callvirt   ""void IMoveable.this[int].set""
    IL_00fe:  leave.s    IL_0119
  }
  catch System.Exception
  {
    IL_0100:  stloc.s    V_6
    IL_0102:  ldarg.0
    IL_0103:  ldc.i4.s   -2
    IL_0105:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_010a:  ldarg.0
    IL_010b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0110:  ldloc.s    V_6
    IL_0112:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0117:  leave.s    IL_012c
  }
  IL_0119:  ldarg.0
  IL_011a:  ldc.i4.s   -2
  IL_011c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0121:  ldarg.0
  IL_0122:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0127:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_012c:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        [WorkItem("https://github.com/dotnet/roslyn/issues/70267")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Index_ThroughArray()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Item2 : Item {}

class Program
{
    static void Main()
    {
        var item1 = new[] {new Item2 {Name = ""1""}};
        Shift1((Item[])item1);

        var item2 = new[] {new Item2 {Name = ""2""}};
        Shift2((Item[])item2);
    }

    static void Shift1<T>(T[] item) where T : class, IMoveable
    {
        item[GetArrayIndex()][GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()][GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item2 {Name = (--value).ToString()};
        return 0;
    }

    static int GetArrayIndex() => 0;
}
";
            // Execution fails due to https://github.com/dotnet/roslyn/issues/70267
            string expectedOutput = null /*@"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
"*/;
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       52 (0x34)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  call       ""int Program.GetArrayIndex()""
  IL_0006:  ldelem     ""T""
  IL_000b:  stloc.1
  IL_000c:  ldloca.s   V_1
  IL_000e:  stloc.0
  IL_000f:  ldarga.s   V_0
  IL_0011:  call       ""int Program.GetOffset<T>(ref T[])""
  IL_0016:  stloc.2
  IL_0017:  ldloc.0
  IL_0018:  ldloc.2
  IL_0019:  ldloc.0
  IL_001a:  ldloc.2
  IL_001b:  constrained. ""T""
  IL_0021:  callvirt   ""int IMoveable.this[int].get""
  IL_0026:  ldc.i4.1
  IL_0027:  add
  IL_0028:  constrained. ""T""
  IL_002e:  callvirt   ""void IMoveable.this[int].set""
  IL_0033:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       79 (0x4f)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarg.0
  IL_0001:  call       ""int Program.GetArrayIndex()""
  IL_0006:  ldelema    ""T""
  IL_000b:  stloc.2
  IL_000c:  ldloca.s   V_4
  IL_000e:  initobj    ""T""
  IL_0014:  ldloc.s    V_4
  IL_0016:  box        ""T""
  IL_001b:  brtrue.s   IL_0028
  IL_001d:  ldloc.2
  IL_001e:  ldobj      ""T""
  IL_0023:  stloc.1
  IL_0024:  ldloca.s   V_1
  IL_0026:  br.s       IL_0029
  IL_0028:  ldloc.2
  IL_0029:  stloc.0
  IL_002a:  ldarga.s   V_0
  IL_002c:  call       ""int Program.GetOffset<T>(ref T[])""
  IL_0031:  stloc.3
  IL_0032:  ldloc.0
  IL_0033:  ldloc.3
  IL_0034:  ldloc.0
  IL_0035:  ldloc.3
  IL_0036:  constrained. ""T""
  IL_003c:  callvirt   ""int IMoveable.this[int].get""
  IL_0041:  ldc.i4.1
  IL_0042:  add
  IL_0043:  constrained. ""T""
  IL_0049:  callvirt   ""void IMoveable.this[int].set""
  IL_004e:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Index_ThroughArray()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new[] {new Item {Name = ""1""}};
        Shift1(item1);

        var item2 = new[] {new Item {Name = ""2""}};
        Shift2(item2);
    }

    static void Shift1<T>(T[] item) where T : struct, IMoveable
    {
        item[GetArrayIndex()][GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()][GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static int GetArrayIndex() => 0;
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       49 (0x31)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  call       ""int Program.GetArrayIndex()""
  IL_0006:  ldelema    ""T""
  IL_000b:  stloc.0
  IL_000c:  ldarga.s   V_0
  IL_000e:  call       ""int Program.GetOffset<T>(ref T[])""
  IL_0013:  stloc.1
  IL_0014:  ldloc.0
  IL_0015:  ldloc.1
  IL_0016:  ldloc.0
  IL_0017:  ldloc.1
  IL_0018:  constrained. ""T""
  IL_001e:  callvirt   ""int IMoveable.this[int].get""
  IL_0023:  ldc.i4.1
  IL_0024:  add
  IL_0025:  constrained. ""T""
  IL_002b:  callvirt   ""void IMoveable.this[int].set""
  IL_0030:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Index_Async_01_ThroughArray()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Item2 : Item {}

class Program
{
    static async Task Main()
    {
        var item1 = new[] {new Item2 {Name = ""1""}};
        await Shift1((Item[])item1);

        var item2 = new[] {new Item2 {Name = ""2""}};
        await Shift2((Item[])item2);
    }

    static async Task Shift1<T>(T[] item) where T : class, IMoveable
    {
        item[GetArrayIndex()][await GetOffsetAsync(GetOffset(ref item))] += 1;
    }

    static async Task Shift2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()][await GetOffsetAsync(GetOffset(ref item))] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item2 {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }

    static int GetArrayIndex() => 0;
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
      // Code size      227 (0xe3)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0062
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T[] Program.<Shift1>d__1<T>.item""
    IL_0011:  call       ""int Program.GetArrayIndex()""
    IL_0016:  ldelem     ""T""
    IL_001b:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0020:  ldarg.0
    IL_0021:  ldflda     ""T[] Program.<Shift1>d__1<T>.item""
    IL_0026:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_002b:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0030:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0035:  stloc.2
    IL_0036:  ldloca.s   V_2
    IL_0038:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003d:  brtrue.s   IL_007e
    IL_003f:  ldarg.0
    IL_0040:  ldc.i4.0
    IL_0041:  dup
    IL_0042:  stloc.0
    IL_0043:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0048:  ldarg.0
    IL_0049:  ldloc.2
    IL_004a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004f:  ldarg.0
    IL_0050:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0055:  ldloca.s   V_2
    IL_0057:  ldarg.0
    IL_0058:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_005d:  leave      IL_00e2
    IL_0062:  ldarg.0
    IL_0063:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  stloc.2
    IL_0069:  ldarg.0
    IL_006a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0075:  ldarg.0
    IL_0076:  ldc.i4.m1
    IL_0077:  dup
    IL_0078:  stloc.0
    IL_0079:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007e:  ldloca.s   V_2
    IL_0080:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0085:  stloc.1
    IL_0086:  ldarg.0
    IL_0087:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008c:  box        ""T""
    IL_0091:  ldloc.1
    IL_0092:  ldarg.0
    IL_0093:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0098:  box        ""T""
    IL_009d:  ldloc.1
    IL_009e:  callvirt   ""int IMoveable.this[int].get""
    IL_00a3:  ldc.i4.1
    IL_00a4:  add
    IL_00a5:  callvirt   ""void IMoveable.this[int].set""
    IL_00aa:  ldarg.0
    IL_00ab:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b0:  initobj    ""T""
    IL_00b6:  leave.s    IL_00cf
  }
  catch System.Exception
  {
    IL_00b8:  stloc.3
    IL_00b9:  ldarg.0
    IL_00ba:  ldc.i4.s   -2
    IL_00bc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c1:  ldarg.0
    IL_00c2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00c7:  ldloc.3
    IL_00c8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00cd:  leave.s    IL_00e2
  }
  IL_00cf:  ldarg.0
  IL_00d0:  ldc.i4.s   -2
  IL_00d2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00d7:  ldarg.0
  IL_00d8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00dd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00e2:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      397 (0x18d)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00b7
    IL_000d:  ldarg.0
    IL_000e:  ldarg.0
    IL_000f:  ldfld      ""T[] Program.<Shift2>d__2<T>.item""
    IL_0014:  stfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0019:  ldarg.0
    IL_001a:  call       ""int Program.GetArrayIndex()""
    IL_001f:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0024:  ldarg.0
    IL_0025:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_002a:  ldarg.0
    IL_002b:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0030:  readonly.
    IL_0032:  ldelema    ""T""
    IL_0037:  pop
    IL_0038:  ldloca.s   V_2
    IL_003a:  initobj    ""T""
    IL_0040:  ldloc.2
    IL_0041:  box        ""T""
    IL_0046:  brtrue.s   IL_0061
    IL_0048:  ldarg.0
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_004f:  ldarg.0
    IL_0050:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0055:  ldelem     ""T""
    IL_005a:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_005f:  br.s       IL_0075
    IL_0061:  ldarg.0
    IL_0062:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0067:  ldarg.0
    IL_0068:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_006d:  readonly.
    IL_006f:  ldelema    ""T""
    IL_0074:  pop
    IL_0075:  ldarg.0
    IL_0076:  ldflda     ""T[] Program.<Shift2>d__2<T>.item""
    IL_007b:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_0080:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0085:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_008a:  stloc.3
    IL_008b:  ldloca.s   V_3
    IL_008d:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0092:  brtrue.s   IL_00d3
    IL_0094:  ldarg.0
    IL_0095:  ldc.i4.0
    IL_0096:  dup
    IL_0097:  stloc.0
    IL_0098:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_009d:  ldarg.0
    IL_009e:  ldloc.3
    IL_009f:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00aa:  ldloca.s   V_3
    IL_00ac:  ldarg.0
    IL_00ad:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00b2:  leave      IL_018c
    IL_00b7:  ldarg.0
    IL_00b8:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00bd:  stloc.3
    IL_00be:  ldarg.0
    IL_00bf:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00c4:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00ca:  ldarg.0
    IL_00cb:  ldc.i4.m1
    IL_00cc:  dup
    IL_00cd:  stloc.0
    IL_00ce:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00d3:  ldloca.s   V_3
    IL_00d5:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00da:  stloc.1
    IL_00db:  ldloca.s   V_2
    IL_00dd:  initobj    ""T""
    IL_00e3:  ldloc.2
    IL_00e4:  box        ""T""
    IL_00e9:  brtrue.s   IL_00f3
    IL_00eb:  ldarg.0
    IL_00ec:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f1:  br.s       IL_0106
    IL_00f3:  ldarg.0
    IL_00f4:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00f9:  ldarg.0
    IL_00fa:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_00ff:  readonly.
    IL_0101:  ldelema    ""T""
    IL_0106:  ldloc.1
    IL_0107:  ldloca.s   V_2
    IL_0109:  initobj    ""T""
    IL_010f:  ldloc.2
    IL_0110:  box        ""T""
    IL_0115:  brtrue.s   IL_011f
    IL_0117:  ldarg.0
    IL_0118:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_011d:  br.s       IL_0132
    IL_011f:  ldarg.0
    IL_0120:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0125:  ldarg.0
    IL_0126:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_012b:  readonly.
    IL_012d:  ldelema    ""T""
    IL_0132:  ldloc.1
    IL_0133:  constrained. ""T""
    IL_0139:  callvirt   ""int IMoveable.this[int].get""
    IL_013e:  ldc.i4.1
    IL_013f:  add
    IL_0140:  constrained. ""T""
    IL_0146:  callvirt   ""void IMoveable.this[int].set""
    IL_014b:  ldarg.0
    IL_014c:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0151:  initobj    ""T""
    IL_0157:  ldarg.0
    IL_0158:  ldnull
    IL_0159:  stfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_015e:  leave.s    IL_0179
  }
  catch System.Exception
  {
    IL_0160:  stloc.s    V_4
    IL_0162:  ldarg.0
    IL_0163:  ldc.i4.s   -2
    IL_0165:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_016a:  ldarg.0
    IL_016b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0170:  ldloc.s    V_4
    IL_0172:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0177:  leave.s    IL_018c
  }
  IL_0179:  ldarg.0
  IL_017a:  ldc.i4.s   -2
  IL_017c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0181:  ldarg.0
  IL_0182:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0187:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_018c:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Index_Async_01_ThroughArray()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new[] {new Item {Name = ""1""}};
        await Shift1(item1);

        var item2 = new[] {new Item {Name = ""2""}};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T[] item) where T : struct, IMoveable
    {
        item[GetArrayIndex()][await GetOffsetAsync(GetOffset(ref item))] += 1;
    }

    static async Task Shift2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()][await GetOffsetAsync(GetOffset(ref item))] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }

    static int GetArrayIndex() => 0;
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      271 (0x10f)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0077
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T[] Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  call       ""int Program.GetArrayIndex()""
    IL_001c:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0021:  ldarg.0
    IL_0022:  ldfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0027:  ldarg.0
    IL_0028:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_002d:  readonly.
    IL_002f:  ldelema    ""T""
    IL_0034:  pop
    IL_0035:  ldarg.0
    IL_0036:  ldflda     ""T[] Program.<Shift1>d__1<T>.item""
    IL_003b:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_0040:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0045:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_004a:  stloc.2
    IL_004b:  ldloca.s   V_2
    IL_004d:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0052:  brtrue.s   IL_0093
    IL_0054:  ldarg.0
    IL_0055:  ldc.i4.0
    IL_0056:  dup
    IL_0057:  stloc.0
    IL_0058:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_005d:  ldarg.0
    IL_005e:  ldloc.2
    IL_005f:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0064:  ldarg.0
    IL_0065:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_006a:  ldloca.s   V_2
    IL_006c:  ldarg.0
    IL_006d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0072:  leave      IL_010e
    IL_0077:  ldarg.0
    IL_0078:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007d:  stloc.2
    IL_007e:  ldarg.0
    IL_007f:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0084:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_008a:  ldarg.0
    IL_008b:  ldc.i4.m1
    IL_008c:  dup
    IL_008d:  stloc.0
    IL_008e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0093:  ldloca.s   V_2
    IL_0095:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_009a:  stloc.1
    IL_009b:  ldarg.0
    IL_009c:  ldfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a1:  ldarg.0
    IL_00a2:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00a7:  readonly.
    IL_00a9:  ldelema    ""T""
    IL_00ae:  ldloc.1
    IL_00af:  ldarg.0
    IL_00b0:  ldfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b5:  ldarg.0
    IL_00b6:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00bb:  readonly.
    IL_00bd:  ldelema    ""T""
    IL_00c2:  ldloc.1
    IL_00c3:  constrained. ""T""
    IL_00c9:  callvirt   ""int IMoveable.this[int].get""
    IL_00ce:  ldc.i4.1
    IL_00cf:  add
    IL_00d0:  constrained. ""T""
    IL_00d6:  callvirt   ""void IMoveable.this[int].set""
    IL_00db:  ldarg.0
    IL_00dc:  ldnull
    IL_00dd:  stfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00e2:  leave.s    IL_00fb
  }
  catch System.Exception
  {
    IL_00e4:  stloc.3
    IL_00e5:  ldarg.0
    IL_00e6:  ldc.i4.s   -2
    IL_00e8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ed:  ldarg.0
    IL_00ee:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00f3:  ldloc.3
    IL_00f4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00f9:  leave.s    IL_010e
  }
  IL_00fb:  ldarg.0
  IL_00fc:  ldc.i4.s   -2
  IL_00fe:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0103:  ldarg.0
  IL_0104:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0109:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_010e:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        [WorkItem("https://github.com/dotnet/roslyn/issues/70267")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Class_ThroughArray()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Item2 : Item {}

class Program
{
    static void Main()
    {
        var item1 = new[] {new Item2 {Name = ""1""}};
        Shift1((Item[])item1);

        var item2 = new[] {new Item2 {Name = ""2""}};
        Shift2((Item[])item2);
    }

    static void Shift1<T>(T[] item) where T : class, IMoveable
    {
        item[GetArrayIndex()][GetOffset(ref item)] ++;
    }

    static void Shift2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()][GetOffset(ref item)] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item2 {Name = (--value).ToString()};
        return 0;
    }

    static int GetArrayIndex() => 0;
}
";
            // Execution fails due to https://github.com/dotnet/roslyn/issues/70267
            string expectedOutput = null /*@"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
"*/;
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       52 (0x34)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  call       ""int Program.GetArrayIndex()""
  IL_0006:  ldelem     ""T""
  IL_000b:  stloc.0
  IL_000c:  ldloca.s   V_0
  IL_000e:  ldarga.s   V_0
  IL_0010:  call       ""int Program.GetOffset<T>(ref T[])""
  IL_0015:  stloc.1
  IL_0016:  dup
  IL_0017:  ldloc.1
  IL_0018:  constrained. ""T""
  IL_001e:  callvirt   ""int IMoveable.this[int].get""
  IL_0023:  stloc.2
  IL_0024:  ldloc.1
  IL_0025:  ldloc.2
  IL_0026:  ldc.i4.1
  IL_0027:  add
  IL_0028:  constrained. ""T""
  IL_002e:  callvirt   ""void IMoveable.this[int].set""
  IL_0033:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       79 (0x4f)
  .maxstack  4
  .locals init (T V_0,
                T& V_1,
                int V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarg.0
  IL_0001:  call       ""int Program.GetArrayIndex()""
  IL_0006:  ldelema    ""T""
  IL_000b:  stloc.1
  IL_000c:  ldloca.s   V_4
  IL_000e:  initobj    ""T""
  IL_0014:  ldloc.s    V_4
  IL_0016:  box        ""T""
  IL_001b:  brtrue.s   IL_0028
  IL_001d:  ldloc.1
  IL_001e:  ldobj      ""T""
  IL_0023:  stloc.0
  IL_0024:  ldloca.s   V_0
  IL_0026:  br.s       IL_0029
  IL_0028:  ldloc.1
  IL_0029:  ldarga.s   V_0
  IL_002b:  call       ""int Program.GetOffset<T>(ref T[])""
  IL_0030:  stloc.2
  IL_0031:  dup
  IL_0032:  ldloc.2
  IL_0033:  constrained. ""T""
  IL_0039:  callvirt   ""int IMoveable.this[int].get""
  IL_003e:  stloc.3
  IL_003f:  ldloc.2
  IL_0040:  ldloc.3
  IL_0041:  ldc.i4.1
  IL_0042:  add
  IL_0043:  constrained. ""T""
  IL_0049:  callvirt   ""void IMoveable.this[int].set""
  IL_004e:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Struct_ThroughArray()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new[] {new Item {Name = ""1""}};
        Shift1(item1);

        var item2 = new[] {new Item {Name = ""2""}};
        Shift2(item2);
    }

    static void Shift1<T>(T[] item) where T : struct, IMoveable
    {
        item[GetArrayIndex()][GetOffset(ref item)] ++;
    }

    static void Shift2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()][GetOffset(ref item)] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static int GetArrayIndex() => 0;
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       49 (0x31)
  .maxstack  4
  .locals init (int V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  call       ""int Program.GetArrayIndex()""
  IL_0006:  ldelema    ""T""
  IL_000b:  ldarga.s   V_0
  IL_000d:  call       ""int Program.GetOffset<T>(ref T[])""
  IL_0012:  stloc.0
  IL_0013:  dup
  IL_0014:  ldloc.0
  IL_0015:  constrained. ""T""
  IL_001b:  callvirt   ""int IMoveable.this[int].get""
  IL_0020:  stloc.1
  IL_0021:  ldloc.0
  IL_0022:  ldloc.1
  IL_0023:  ldc.i4.1
  IL_0024:  add
  IL_0025:  constrained. ""T""
  IL_002b:  callvirt   ""void IMoveable.this[int].set""
  IL_0030:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Class_Async_01_ThroughArray()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Item2 : Item {}

class Program
{
    static async Task Main()
    {
        var item1 = new[] {new Item2 {Name = ""1""}};
        await Shift1((Item[])item1);

        var item2 = new[] {new Item2 {Name = ""2""}};
        await Shift2((Item[])item2);
    }

    static async Task Shift1<T>(T[] item) where T : class, IMoveable
    {
        item[GetArrayIndex()][await GetOffsetAsync(GetOffset(ref item))] ++;
    }

    static async Task Shift2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()][await GetOffsetAsync(GetOffset(ref item))] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item2 {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }

    static int GetArrayIndex() => 0;
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      231 (0xe7)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0062
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T[] Program.<Shift1>d__1<T>.item""
    IL_0011:  call       ""int Program.GetArrayIndex()""
    IL_0016:  ldelem     ""T""
    IL_001b:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0020:  ldarg.0
    IL_0021:  ldflda     ""T[] Program.<Shift1>d__1<T>.item""
    IL_0026:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_002b:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0030:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0035:  stloc.3
    IL_0036:  ldloca.s   V_3
    IL_0038:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003d:  brtrue.s   IL_007e
    IL_003f:  ldarg.0
    IL_0040:  ldc.i4.0
    IL_0041:  dup
    IL_0042:  stloc.0
    IL_0043:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0048:  ldarg.0
    IL_0049:  ldloc.3
    IL_004a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004f:  ldarg.0
    IL_0050:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0055:  ldloca.s   V_3
    IL_0057:  ldarg.0
    IL_0058:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_005d:  leave      IL_00e6
    IL_0062:  ldarg.0
    IL_0063:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  stloc.3
    IL_0069:  ldarg.0
    IL_006a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0075:  ldarg.0
    IL_0076:  ldc.i4.m1
    IL_0077:  dup
    IL_0078:  stloc.0
    IL_0079:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007e:  ldloca.s   V_3
    IL_0080:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0085:  stloc.1
    IL_0086:  ldarg.0
    IL_0087:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008c:  box        ""T""
    IL_0091:  ldloc.1
    IL_0092:  callvirt   ""int IMoveable.this[int].get""
    IL_0097:  stloc.2
    IL_0098:  ldarg.0
    IL_0099:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_009e:  box        ""T""
    IL_00a3:  ldloc.1
    IL_00a4:  ldloc.2
    IL_00a5:  ldc.i4.1
    IL_00a6:  add
    IL_00a7:  callvirt   ""void IMoveable.this[int].set""
    IL_00ac:  ldarg.0
    IL_00ad:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b2:  initobj    ""T""
    IL_00b8:  leave.s    IL_00d3
  }
  catch System.Exception
  {
    IL_00ba:  stloc.s    V_4
    IL_00bc:  ldarg.0
    IL_00bd:  ldc.i4.s   -2
    IL_00bf:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c4:  ldarg.0
    IL_00c5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00ca:  ldloc.s    V_4
    IL_00cc:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d1:  leave.s    IL_00e6
  }
  IL_00d3:  ldarg.0
  IL_00d4:  ldc.i4.s   -2
  IL_00d6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00db:  ldarg.0
  IL_00dc:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00e1:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00e6:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      402 (0x192)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00b9
    IL_000d:  ldarg.0
    IL_000e:  ldarg.0
    IL_000f:  ldfld      ""T[] Program.<Shift2>d__2<T>.item""
    IL_0014:  stfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0019:  ldarg.0
    IL_001a:  call       ""int Program.GetArrayIndex()""
    IL_001f:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0024:  ldarg.0
    IL_0025:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_002a:  ldarg.0
    IL_002b:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0030:  readonly.
    IL_0032:  ldelema    ""T""
    IL_0037:  pop
    IL_0038:  ldloca.s   V_3
    IL_003a:  initobj    ""T""
    IL_0040:  ldloc.3
    IL_0041:  box        ""T""
    IL_0046:  brtrue.s   IL_0061
    IL_0048:  ldarg.0
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_004f:  ldarg.0
    IL_0050:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0055:  ldelem     ""T""
    IL_005a:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_005f:  br.s       IL_0075
    IL_0061:  ldarg.0
    IL_0062:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0067:  ldarg.0
    IL_0068:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_006d:  readonly.
    IL_006f:  ldelema    ""T""
    IL_0074:  pop
    IL_0075:  ldarg.0
    IL_0076:  ldflda     ""T[] Program.<Shift2>d__2<T>.item""
    IL_007b:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_0080:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0085:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_008a:  stloc.s    V_4
    IL_008c:  ldloca.s   V_4
    IL_008e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0093:  brtrue.s   IL_00d6
    IL_0095:  ldarg.0
    IL_0096:  ldc.i4.0
    IL_0097:  dup
    IL_0098:  stloc.0
    IL_0099:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_009e:  ldarg.0
    IL_009f:  ldloc.s    V_4
    IL_00a1:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00a6:  ldarg.0
    IL_00a7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00ac:  ldloca.s   V_4
    IL_00ae:  ldarg.0
    IL_00af:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00b4:  leave      IL_0191
    IL_00b9:  ldarg.0
    IL_00ba:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00bf:  stloc.s    V_4
    IL_00c1:  ldarg.0
    IL_00c2:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00c7:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00cd:  ldarg.0
    IL_00ce:  ldc.i4.m1
    IL_00cf:  dup
    IL_00d0:  stloc.0
    IL_00d1:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00d6:  ldloca.s   V_4
    IL_00d8:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00dd:  stloc.1
    IL_00de:  ldloca.s   V_3
    IL_00e0:  initobj    ""T""
    IL_00e6:  ldloc.3
    IL_00e7:  box        ""T""
    IL_00ec:  brtrue.s   IL_00f6
    IL_00ee:  ldarg.0
    IL_00ef:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f4:  br.s       IL_0109
    IL_00f6:  ldarg.0
    IL_00f7:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00fc:  ldarg.0
    IL_00fd:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0102:  readonly.
    IL_0104:  ldelema    ""T""
    IL_0109:  ldloc.1
    IL_010a:  constrained. ""T""
    IL_0110:  callvirt   ""int IMoveable.this[int].get""
    IL_0115:  stloc.2
    IL_0116:  ldloca.s   V_3
    IL_0118:  initobj    ""T""
    IL_011e:  ldloc.3
    IL_011f:  box        ""T""
    IL_0124:  brtrue.s   IL_012e
    IL_0126:  ldarg.0
    IL_0127:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_012c:  br.s       IL_0141
    IL_012e:  ldarg.0
    IL_012f:  ldfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0134:  ldarg.0
    IL_0135:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_013a:  readonly.
    IL_013c:  ldelema    ""T""
    IL_0141:  ldloc.1
    IL_0142:  ldloc.2
    IL_0143:  ldc.i4.1
    IL_0144:  add
    IL_0145:  constrained. ""T""
    IL_014b:  callvirt   ""void IMoveable.this[int].set""
    IL_0150:  ldarg.0
    IL_0151:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0156:  initobj    ""T""
    IL_015c:  ldarg.0
    IL_015d:  ldnull
    IL_015e:  stfld      ""T[] Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0163:  leave.s    IL_017e
  }
  catch System.Exception
  {
    IL_0165:  stloc.s    V_5
    IL_0167:  ldarg.0
    IL_0168:  ldc.i4.s   -2
    IL_016a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_016f:  ldarg.0
    IL_0170:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0175:  ldloc.s    V_5
    IL_0177:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_017c:  leave.s    IL_0191
  }
  IL_017e:  ldarg.0
  IL_017f:  ldc.i4.s   -2
  IL_0181:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0186:  ldarg.0
  IL_0187:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_018c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0191:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Increment_Indexer_Struct_Async_01_ThroughArray()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new[] {new Item {Name = ""1""}};
        await Shift1(item1);

        var item2 = new[] {new Item {Name = ""2""}};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T[] item) where T : struct, IMoveable
    {
        item[GetArrayIndex()][await GetOffsetAsync(GetOffset(ref item))] ++;
    }

    static async Task Shift2<T>(T[] item) where T : IMoveable
    {
        item[GetArrayIndex()][await GetOffsetAsync(GetOffset(ref item))] ++;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T[] item)
    {
        item[0] = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }

    static int GetArrayIndex() => 0;
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      275 (0x113)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0077
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T[] Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  call       ""int Program.GetArrayIndex()""
    IL_001c:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0021:  ldarg.0
    IL_0022:  ldfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0027:  ldarg.0
    IL_0028:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_002d:  readonly.
    IL_002f:  ldelema    ""T""
    IL_0034:  pop
    IL_0035:  ldarg.0
    IL_0036:  ldflda     ""T[] Program.<Shift1>d__1<T>.item""
    IL_003b:  call       ""int Program.GetOffset<T>(ref T[])""
    IL_0040:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0045:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_004a:  stloc.3
    IL_004b:  ldloca.s   V_3
    IL_004d:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0052:  brtrue.s   IL_0093
    IL_0054:  ldarg.0
    IL_0055:  ldc.i4.0
    IL_0056:  dup
    IL_0057:  stloc.0
    IL_0058:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_005d:  ldarg.0
    IL_005e:  ldloc.3
    IL_005f:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0064:  ldarg.0
    IL_0065:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_006a:  ldloca.s   V_3
    IL_006c:  ldarg.0
    IL_006d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0072:  leave      IL_0112
    IL_0077:  ldarg.0
    IL_0078:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007d:  stloc.3
    IL_007e:  ldarg.0
    IL_007f:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0084:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_008a:  ldarg.0
    IL_008b:  ldc.i4.m1
    IL_008c:  dup
    IL_008d:  stloc.0
    IL_008e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0093:  ldloca.s   V_3
    IL_0095:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_009a:  stloc.1
    IL_009b:  ldarg.0
    IL_009c:  ldfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a1:  ldarg.0
    IL_00a2:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00a7:  readonly.
    IL_00a9:  ldelema    ""T""
    IL_00ae:  ldloc.1
    IL_00af:  constrained. ""T""
    IL_00b5:  callvirt   ""int IMoveable.this[int].get""
    IL_00ba:  stloc.2
    IL_00bb:  ldarg.0
    IL_00bc:  ldfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00c1:  ldarg.0
    IL_00c2:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00c7:  readonly.
    IL_00c9:  ldelema    ""T""
    IL_00ce:  ldloc.1
    IL_00cf:  ldloc.2
    IL_00d0:  ldc.i4.1
    IL_00d1:  add
    IL_00d2:  constrained. ""T""
    IL_00d8:  callvirt   ""void IMoveable.this[int].set""
    IL_00dd:  ldarg.0
    IL_00de:  ldnull
    IL_00df:  stfld      ""T[] Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00e4:  leave.s    IL_00ff
  }
  catch System.Exception
  {
    IL_00e6:  stloc.s    V_4
    IL_00e8:  ldarg.0
    IL_00e9:  ldc.i4.s   -2
    IL_00eb:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00f0:  ldarg.0
    IL_00f1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00f6:  ldloc.s    V_4
    IL_00f8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00fd:  leave.s    IL_0112
  }
  IL_00ff:  ldarg.0
  IL_0100:  ldc.i4.s   -2
  IL_0102:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0107:  ldarg.0
  IL_0108:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_010d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0112:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_Index()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] ??= 1;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       73 (0x49)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_1
  IL_0004:  stloc.0
  IL_0005:  ldarga.s   V_0
  IL_0007:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000c:  stloc.2
  IL_000d:  ldloc.0
  IL_000e:  ldloc.2
  IL_000f:  constrained. ""T""
  IL_0015:  callvirt   ""int? IMoveable.this[int].get""
  IL_001a:  stloc.3
  IL_001b:  ldloca.s   V_3
  IL_001d:  call       ""int int?.GetValueOrDefault()""
  IL_0022:  stloc.s    V_4
  IL_0024:  ldloca.s   V_3
  IL_0026:  call       ""bool int?.HasValue.get""
  IL_002b:  brtrue.s   IL_0048
  IL_002d:  ldc.i4.1
  IL_002e:  stloc.s    V_4
  IL_0030:  ldloc.0
  IL_0031:  ldloc.2
  IL_0032:  ldloca.s   V_5
  IL_0034:  ldloc.s    V_4
  IL_0036:  call       ""int?..ctor(int)""
  IL_003b:  ldloc.s    V_5
  IL_003d:  constrained. ""T""
  IL_0043:  callvirt   ""void IMoveable.this[int].set""
  IL_0048:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      102 (0x66)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int? V_4,
                int V_5,
                T V_6,
                int? V_7)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_6
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_6
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  ldloc.3
  IL_002b:  constrained. ""T""
  IL_0031:  callvirt   ""int? IMoveable.this[int].get""
  IL_0036:  stloc.s    V_4
  IL_0038:  ldloca.s   V_4
  IL_003a:  call       ""int int?.GetValueOrDefault()""
  IL_003f:  stloc.s    V_5
  IL_0041:  ldloca.s   V_4
  IL_0043:  call       ""bool int?.HasValue.get""
  IL_0048:  brtrue.s   IL_0065
  IL_004a:  ldc.i4.1
  IL_004b:  stloc.s    V_5
  IL_004d:  ldloc.0
  IL_004e:  ldloc.3
  IL_004f:  ldloca.s   V_7
  IL_0051:  ldloc.s    V_5
  IL_0053:  call       ""int?..ctor(int)""
  IL_0058:  ldloc.s    V_7
  IL_005a:  constrained. ""T""
  IL_0060:  callvirt   ""void IMoveable.this[int].set""
  IL_0065:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_Index()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] ??= 1;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       68 (0x44)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  ldloc.1
  IL_000d:  constrained. ""T""
  IL_0013:  callvirt   ""int? IMoveable.this[int].get""
  IL_0018:  stloc.2
  IL_0019:  ldloca.s   V_2
  IL_001b:  call       ""int int?.GetValueOrDefault()""
  IL_0020:  stloc.3
  IL_0021:  ldloca.s   V_2
  IL_0023:  call       ""bool int?.HasValue.get""
  IL_0028:  brtrue.s   IL_0043
  IL_002a:  ldc.i4.1
  IL_002b:  stloc.3
  IL_002c:  ldloc.0
  IL_002d:  ldloc.1
  IL_002e:  ldloca.s   V_4
  IL_0030:  ldloc.3
  IL_0031:  call       ""int?..ctor(int)""
  IL_0036:  ldloc.s    V_4
  IL_0038:  constrained. ""T""
  IL_003e:  callvirt   ""void IMoveable.this[int].set""
  IL_0043:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_Index_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] ??= 1;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       77 (0x4d)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.1
  IL_0007:  ldloca.s   V_1
  IL_0009:  stloc.0
  IL_000a:  ldarg.0
  IL_000b:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0010:  stloc.2
  IL_0011:  ldloc.0
  IL_0012:  ldloc.2
  IL_0013:  constrained. ""T""
  IL_0019:  callvirt   ""int? IMoveable.this[int].get""
  IL_001e:  stloc.3
  IL_001f:  ldloca.s   V_3
  IL_0021:  call       ""int int?.GetValueOrDefault()""
  IL_0026:  stloc.s    V_4
  IL_0028:  ldloca.s   V_3
  IL_002a:  call       ""bool int?.HasValue.get""
  IL_002f:  brtrue.s   IL_004c
  IL_0031:  ldc.i4.1
  IL_0032:  stloc.s    V_4
  IL_0034:  ldloc.0
  IL_0035:  ldloc.2
  IL_0036:  ldloca.s   V_5
  IL_0038:  ldloc.s    V_4
  IL_003a:  call       ""int?..ctor(int)""
  IL_003f:  ldloc.s    V_5
  IL_0041:  constrained. ""T""
  IL_0047:  callvirt   ""void IMoveable.this[int].set""
  IL_004c:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      100 (0x64)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int? V_4,
                int V_5,
                T V_6,
                int? V_7)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_6
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_6
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  ldloc.3
  IL_0029:  constrained. ""T""
  IL_002f:  callvirt   ""int? IMoveable.this[int].get""
  IL_0034:  stloc.s    V_4
  IL_0036:  ldloca.s   V_4
  IL_0038:  call       ""int int?.GetValueOrDefault()""
  IL_003d:  stloc.s    V_5
  IL_003f:  ldloca.s   V_4
  IL_0041:  call       ""bool int?.HasValue.get""
  IL_0046:  brtrue.s   IL_0063
  IL_0048:  ldc.i4.1
  IL_0049:  stloc.s    V_5
  IL_004b:  ldloc.0
  IL_004c:  ldloc.3
  IL_004d:  ldloca.s   V_7
  IL_004f:  ldloc.s    V_5
  IL_0051:  call       ""int?..ctor(int)""
  IL_0056:  ldloc.s    V_7
  IL_0058:  constrained. ""T""
  IL_005e:  callvirt   ""void IMoveable.this[int].set""
  IL_0063:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_Index_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] ??= 1;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       66 (0x42)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  ldloc.1
  IL_000b:  constrained. ""T""
  IL_0011:  callvirt   ""int? IMoveable.this[int].get""
  IL_0016:  stloc.2
  IL_0017:  ldloca.s   V_2
  IL_0019:  call       ""int int?.GetValueOrDefault()""
  IL_001e:  stloc.3
  IL_001f:  ldloca.s   V_2
  IL_0021:  call       ""bool int?.HasValue.get""
  IL_0026:  brtrue.s   IL_0041
  IL_0028:  ldc.i4.1
  IL_0029:  stloc.3
  IL_002a:  ldloc.0
  IL_002b:  ldloc.1
  IL_002c:  ldloca.s   V_4
  IL_002e:  ldloc.3
  IL_002f:  call       ""int?..ctor(int)""
  IL_0034:  ldloc.s    V_4
  IL_0036:  constrained. ""T""
  IL_003c:  callvirt   ""void IMoveable.this[int].set""
  IL_0041:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_Index_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      249 (0xf9)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_005a
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.s    V_4
    IL_002d:  ldloca.s   V_4
    IL_002f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0034:  brtrue.s   IL_0077
    IL_0036:  ldarg.0
    IL_0037:  ldc.i4.0
    IL_0038:  dup
    IL_0039:  stloc.0
    IL_003a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003f:  ldarg.0
    IL_0040:  ldloc.s    V_4
    IL_0042:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0047:  ldarg.0
    IL_0048:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004d:  ldloca.s   V_4
    IL_004f:  ldarg.0
    IL_0050:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0055:  leave      IL_00f8
    IL_005a:  ldarg.0
    IL_005b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0060:  stloc.s    V_4
    IL_0062:  ldarg.0
    IL_0063:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006e:  ldarg.0
    IL_006f:  ldc.i4.m1
    IL_0070:  dup
    IL_0071:  stloc.0
    IL_0072:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0077:  ldloca.s   V_4
    IL_0079:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007e:  stloc.1
    IL_007f:  ldarg.0
    IL_0080:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0085:  box        ""T""
    IL_008a:  ldloc.1
    IL_008b:  callvirt   ""int? IMoveable.this[int].get""
    IL_0090:  stloc.2
    IL_0091:  ldloca.s   V_2
    IL_0093:  call       ""int int?.GetValueOrDefault()""
    IL_0098:  stloc.3
    IL_0099:  ldloca.s   V_2
    IL_009b:  call       ""bool int?.HasValue.get""
    IL_00a0:  brtrue.s   IL_00be
    IL_00a2:  ldc.i4.1
    IL_00a3:  stloc.3
    IL_00a4:  ldarg.0
    IL_00a5:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00aa:  box        ""T""
    IL_00af:  ldloc.1
    IL_00b0:  ldloc.3
    IL_00b1:  newobj     ""int?..ctor(int)""
    IL_00b6:  dup
    IL_00b7:  stloc.s    V_5
    IL_00b9:  callvirt   ""void IMoveable.this[int].set""
    IL_00be:  ldarg.0
    IL_00bf:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00c4:  initobj    ""T""
    IL_00ca:  leave.s    IL_00e5
  }
  catch System.Exception
  {
    IL_00cc:  stloc.s    V_6
    IL_00ce:  ldarg.0
    IL_00cf:  ldc.i4.s   -2
    IL_00d1:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00d6:  ldarg.0
    IL_00d7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00dc:  ldloc.s    V_6
    IL_00de:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00e3:  leave.s    IL_00f8
  }
  IL_00e5:  ldarg.0
  IL_00e6:  ldc.i4.s   -2
  IL_00e8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00ed:  ldarg.0
  IL_00ee:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00f3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00f8:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      318 (0x13e)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006b
    IL_000a:  ldloca.s   V_4
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.s    V_4
    IL_0014:  box        ""T""
    IL_0019:  brtrue.s   IL_0027
    IL_001b:  ldarg.0
    IL_001c:  ldarg.0
    IL_001d:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0022:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0027:  ldarg.0
    IL_0028:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002d:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0032:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0037:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003c:  stloc.s    V_5
    IL_003e:  ldloca.s   V_5
    IL_0040:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0045:  brtrue.s   IL_0088
    IL_0047:  ldarg.0
    IL_0048:  ldc.i4.0
    IL_0049:  dup
    IL_004a:  stloc.0
    IL_004b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0050:  ldarg.0
    IL_0051:  ldloc.s    V_5
    IL_0053:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  ldarg.0
    IL_0059:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005e:  ldloca.s   V_5
    IL_0060:  ldarg.0
    IL_0061:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0066:  leave      IL_013d
    IL_006b:  ldarg.0
    IL_006c:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0071:  stloc.s    V_5
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0079:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007f:  ldarg.0
    IL_0080:  ldc.i4.m1
    IL_0081:  dup
    IL_0082:  stloc.0
    IL_0083:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0088:  ldloca.s   V_5
    IL_008a:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008f:  stloc.1
    IL_0090:  ldloca.s   V_4
    IL_0092:  initobj    ""T""
    IL_0098:  ldloc.s    V_4
    IL_009a:  box        ""T""
    IL_009f:  brtrue.s   IL_00a9
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a7:  br.s       IL_00af
    IL_00a9:  ldarg.0
    IL_00aa:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00af:  ldloc.1
    IL_00b0:  constrained. ""T""
    IL_00b6:  callvirt   ""int? IMoveable.this[int].get""
    IL_00bb:  stloc.2
    IL_00bc:  ldloca.s   V_2
    IL_00be:  call       ""int int?.GetValueOrDefault()""
    IL_00c3:  stloc.3
    IL_00c4:  ldloca.s   V_2
    IL_00c6:  call       ""bool int?.HasValue.get""
    IL_00cb:  brtrue.s   IL_0103
    IL_00cd:  ldc.i4.1
    IL_00ce:  stloc.3
    IL_00cf:  ldloca.s   V_4
    IL_00d1:  initobj    ""T""
    IL_00d7:  ldloc.s    V_4
    IL_00d9:  box        ""T""
    IL_00de:  brtrue.s   IL_00e8
    IL_00e0:  ldarg.0
    IL_00e1:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00e6:  br.s       IL_00ee
    IL_00e8:  ldarg.0
    IL_00e9:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00ee:  ldloc.1
    IL_00ef:  ldloc.3
    IL_00f0:  newobj     ""int?..ctor(int)""
    IL_00f5:  dup
    IL_00f6:  stloc.s    V_6
    IL_00f8:  constrained. ""T""
    IL_00fe:  callvirt   ""void IMoveable.this[int].set""
    IL_0103:  ldarg.0
    IL_0104:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0109:  initobj    ""T""
    IL_010f:  leave.s    IL_012a
  }
  catch System.Exception
  {
    IL_0111:  stloc.s    V_7
    IL_0113:  ldarg.0
    IL_0114:  ldc.i4.s   -2
    IL_0116:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_011b:  ldarg.0
    IL_011c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0121:  ldloc.s    V_7
    IL_0123:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0128:  leave.s    IL_013d
  }
  IL_012a:  ldarg.0
  IL_012b:  ldc.i4.s   -2
  IL_012d:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0132:  ldarg.0
  IL_0133:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0138:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_013d:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_Index_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      227 (0xe3)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004e
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.s    V_4
    IL_0021:  ldloca.s   V_4
    IL_0023:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0028:  brtrue.s   IL_006b
    IL_002a:  ldarg.0
    IL_002b:  ldc.i4.0
    IL_002c:  dup
    IL_002d:  stloc.0
    IL_002e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0033:  ldarg.0
    IL_0034:  ldloc.s    V_4
    IL_0036:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_003b:  ldarg.0
    IL_003c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0041:  ldloca.s   V_4
    IL_0043:  ldarg.0
    IL_0044:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0049:  leave      IL_00e2
    IL_004e:  ldarg.0
    IL_004f:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0054:  stloc.s    V_4
    IL_0056:  ldarg.0
    IL_0057:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0062:  ldarg.0
    IL_0063:  ldc.i4.m1
    IL_0064:  dup
    IL_0065:  stloc.0
    IL_0066:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_006b:  ldloca.s   V_4
    IL_006d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0072:  stloc.1
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0079:  ldloc.1
    IL_007a:  constrained. ""T""
    IL_0080:  callvirt   ""int? IMoveable.this[int].get""
    IL_0085:  stloc.2
    IL_0086:  ldloca.s   V_2
    IL_0088:  call       ""int int?.GetValueOrDefault()""
    IL_008d:  stloc.3
    IL_008e:  ldloca.s   V_2
    IL_0090:  call       ""bool int?.HasValue.get""
    IL_0095:  brtrue.s   IL_00b4
    IL_0097:  ldc.i4.1
    IL_0098:  stloc.3
    IL_0099:  ldarg.0
    IL_009a:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_009f:  ldloc.1
    IL_00a0:  ldloc.3
    IL_00a1:  newobj     ""int?..ctor(int)""
    IL_00a6:  dup
    IL_00a7:  stloc.s    V_5
    IL_00a9:  constrained. ""T""
    IL_00af:  callvirt   ""void IMoveable.this[int].set""
    IL_00b4:  leave.s    IL_00cf
  }
  catch System.Exception
  {
    IL_00b6:  stloc.s    V_6
    IL_00b8:  ldarg.0
    IL_00b9:  ldc.i4.s   -2
    IL_00bb:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c0:  ldarg.0
    IL_00c1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00c6:  ldloc.s    V_6
    IL_00c8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00cd:  leave.s    IL_00e2
  }
  IL_00cf:  ldarg.0
  IL_00d0:  ldc.i4.s   -2
  IL_00d2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00d7:  ldarg.0
  IL_00d8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00dd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00e2:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_Index_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      353 (0x161)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                int? V_4,
                int V_5,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_6,
                int? V_7,
                System.Exception V_8)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00be
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_0160
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldarg.0
    IL_0070:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0075:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_007a:  ldarg.0
    IL_007b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0080:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0085:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_008a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_008f:  stloc.s    V_6
    IL_0091:  ldloca.s   V_6
    IL_0093:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0098:  brtrue.s   IL_00db
    IL_009a:  ldarg.0
    IL_009b:  ldc.i4.1
    IL_009c:  dup
    IL_009d:  stloc.0
    IL_009e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00a3:  ldarg.0
    IL_00a4:  ldloc.s    V_6
    IL_00a6:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00ab:  ldarg.0
    IL_00ac:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00b1:  ldloca.s   V_6
    IL_00b3:  ldarg.0
    IL_00b4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00b9:  leave      IL_0160
    IL_00be:  ldarg.0
    IL_00bf:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00c4:  stloc.s    V_6
    IL_00c6:  ldarg.0
    IL_00c7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00cc:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00d2:  ldarg.0
    IL_00d3:  ldc.i4.m1
    IL_00d4:  dup
    IL_00d5:  stloc.0
    IL_00d6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00db:  ldloca.s   V_6
    IL_00dd:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00e2:  stloc.3
    IL_00e3:  ldarg.0
    IL_00e4:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00e9:  box        ""T""
    IL_00ee:  ldloc.3
    IL_00ef:  callvirt   ""int? IMoveable.this[int].get""
    IL_00f4:  stloc.s    V_4
    IL_00f6:  ldloca.s   V_4
    IL_00f8:  call       ""int int?.GetValueOrDefault()""
    IL_00fd:  stloc.s    V_5
    IL_00ff:  ldloca.s   V_4
    IL_0101:  call       ""bool int?.HasValue.get""
    IL_0106:  brtrue.s   IL_0126
    IL_0108:  ldc.i4.1
    IL_0109:  stloc.s    V_5
    IL_010b:  ldarg.0
    IL_010c:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0111:  box        ""T""
    IL_0116:  ldloc.3
    IL_0117:  ldloc.s    V_5
    IL_0119:  newobj     ""int?..ctor(int)""
    IL_011e:  dup
    IL_011f:  stloc.s    V_7
    IL_0121:  callvirt   ""void IMoveable.this[int].set""
    IL_0126:  ldarg.0
    IL_0127:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_012c:  initobj    ""T""
    IL_0132:  leave.s    IL_014d
  }
  catch System.Exception
  {
    IL_0134:  stloc.s    V_8
    IL_0136:  ldarg.0
    IL_0137:  ldc.i4.s   -2
    IL_0139:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_013e:  ldarg.0
    IL_013f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0144:  ldloc.s    V_8
    IL_0146:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_014b:  leave.s    IL_0160
  }
  IL_014d:  ldarg.0
  IL_014e:  ldc.i4.s   -2
  IL_0150:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0155:  ldarg.0
  IL_0156:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_015b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0160:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      422 (0x1a6)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                int? V_4,
                int V_5,
                T V_6,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_7,
                int? V_8,
                System.Exception V_9)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00cf
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift2>d__2<T>)""
    IL_0046:  leave      IL_01a5
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldloca.s   V_6
    IL_0070:  initobj    ""T""
    IL_0076:  ldloc.s    V_6
    IL_0078:  box        ""T""
    IL_007d:  brtrue.s   IL_008b
    IL_007f:  ldarg.0
    IL_0080:  ldarg.0
    IL_0081:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0086:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0091:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0096:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_009b:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00a0:  stloc.s    V_7
    IL_00a2:  ldloca.s   V_7
    IL_00a4:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00a9:  brtrue.s   IL_00ec
    IL_00ab:  ldarg.0
    IL_00ac:  ldc.i4.1
    IL_00ad:  dup
    IL_00ae:  stloc.0
    IL_00af:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00b4:  ldarg.0
    IL_00b5:  ldloc.s    V_7
    IL_00b7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00bc:  ldarg.0
    IL_00bd:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00c2:  ldloca.s   V_7
    IL_00c4:  ldarg.0
    IL_00c5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00ca:  leave      IL_01a5
    IL_00cf:  ldarg.0
    IL_00d0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00d5:  stloc.s    V_7
    IL_00d7:  ldarg.0
    IL_00d8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__2""
    IL_00dd:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00e3:  ldarg.0
    IL_00e4:  ldc.i4.m1
    IL_00e5:  dup
    IL_00e6:  stloc.0
    IL_00e7:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00ec:  ldloca.s   V_7
    IL_00ee:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00f3:  stloc.3
    IL_00f4:  ldloca.s   V_6
    IL_00f6:  initobj    ""T""
    IL_00fc:  ldloc.s    V_6
    IL_00fe:  box        ""T""
    IL_0103:  brtrue.s   IL_010d
    IL_0105:  ldarg.0
    IL_0106:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_010b:  br.s       IL_0113
    IL_010d:  ldarg.0
    IL_010e:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0113:  ldloc.3
    IL_0114:  constrained. ""T""
    IL_011a:  callvirt   ""int? IMoveable.this[int].get""
    IL_011f:  stloc.s    V_4
    IL_0121:  ldloca.s   V_4
    IL_0123:  call       ""int int?.GetValueOrDefault()""
    IL_0128:  stloc.s    V_5
    IL_012a:  ldloca.s   V_4
    IL_012c:  call       ""bool int?.HasValue.get""
    IL_0131:  brtrue.s   IL_016b
    IL_0133:  ldc.i4.1
    IL_0134:  stloc.s    V_5
    IL_0136:  ldloca.s   V_6
    IL_0138:  initobj    ""T""
    IL_013e:  ldloc.s    V_6
    IL_0140:  box        ""T""
    IL_0145:  brtrue.s   IL_014f
    IL_0147:  ldarg.0
    IL_0148:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_014d:  br.s       IL_0155
    IL_014f:  ldarg.0
    IL_0150:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0155:  ldloc.3
    IL_0156:  ldloc.s    V_5
    IL_0158:  newobj     ""int?..ctor(int)""
    IL_015d:  dup
    IL_015e:  stloc.s    V_8
    IL_0160:  constrained. ""T""
    IL_0166:  callvirt   ""void IMoveable.this[int].set""
    IL_016b:  ldarg.0
    IL_016c:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0171:  initobj    ""T""
    IL_0177:  leave.s    IL_0192
  }
  catch System.Exception
  {
    IL_0179:  stloc.s    V_9
    IL_017b:  ldarg.0
    IL_017c:  ldc.i4.s   -2
    IL_017e:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0183:  ldarg.0
    IL_0184:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0189:  ldloc.s    V_9
    IL_018b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0190:  leave.s    IL_01a5
  }
  IL_0192:  ldarg.0
  IL_0193:  ldc.i4.s   -2
  IL_0195:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_019a:  ldarg.0
  IL_019b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_01a0:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_01a5:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_Index_Async_02()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        await Task.Yield();
        item[await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-1'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      331 (0x14b)
  .maxstack  4
  .locals init (int V_0,
                System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter V_1,
                System.Runtime.CompilerServices.YieldAwaitable V_2,
                int V_3,
                int? V_4,
                int V_5,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_6,
                int? V_7,
                System.Exception V_8)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004b
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00b2
    IL_0011:  call       ""System.Runtime.CompilerServices.YieldAwaitable System.Threading.Tasks.Task.Yield()""
    IL_0016:  stloc.2
    IL_0017:  ldloca.s   V_2
    IL_0019:  call       ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter System.Runtime.CompilerServices.YieldAwaitable.GetAwaiter()""
    IL_001e:  stloc.1
    IL_001f:  ldloca.s   V_1
    IL_0021:  call       ""bool System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.IsCompleted.get""
    IL_0026:  brtrue.s   IL_0067
    IL_0028:  ldarg.0
    IL_0029:  ldc.i4.0
    IL_002a:  dup
    IL_002b:  stloc.0
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0031:  ldarg.0
    IL_0032:  ldloc.1
    IL_0033:  stfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0038:  ldarg.0
    IL_0039:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003e:  ldloca.s   V_1
    IL_0040:  ldarg.0
    IL_0041:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter, ref Program.<Shift1>d__1<T>)""
    IL_0046:  leave      IL_014a
    IL_004b:  ldarg.0
    IL_004c:  ldfld      ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  stloc.1
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter Program.<Shift1>d__1<T>.<>u__1""
    IL_0058:  initobj    ""System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter""
    IL_005e:  ldarg.0
    IL_005f:  ldc.i4.m1
    IL_0060:  dup
    IL_0061:  stloc.0
    IL_0062:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0067:  ldloca.s   V_1
    IL_0069:  call       ""void System.Runtime.CompilerServices.YieldAwaitable.YieldAwaiter.GetResult()""
    IL_006e:  ldarg.0
    IL_006f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0074:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0079:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_007e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0083:  stloc.s    V_6
    IL_0085:  ldloca.s   V_6
    IL_0087:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_008c:  brtrue.s   IL_00cf
    IL_008e:  ldarg.0
    IL_008f:  ldc.i4.1
    IL_0090:  dup
    IL_0091:  stloc.0
    IL_0092:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0097:  ldarg.0
    IL_0098:  ldloc.s    V_6
    IL_009a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_009f:  ldarg.0
    IL_00a0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00a5:  ldloca.s   V_6
    IL_00a7:  ldarg.0
    IL_00a8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00ad:  leave      IL_014a
    IL_00b2:  ldarg.0
    IL_00b3:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00b8:  stloc.s    V_6
    IL_00ba:  ldarg.0
    IL_00bb:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__2""
    IL_00c0:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00c6:  ldarg.0
    IL_00c7:  ldc.i4.m1
    IL_00c8:  dup
    IL_00c9:  stloc.0
    IL_00ca:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00cf:  ldloca.s   V_6
    IL_00d1:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00d6:  stloc.3
    IL_00d7:  ldarg.0
    IL_00d8:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00dd:  ldloc.3
    IL_00de:  constrained. ""T""
    IL_00e4:  callvirt   ""int? IMoveable.this[int].get""
    IL_00e9:  stloc.s    V_4
    IL_00eb:  ldloca.s   V_4
    IL_00ed:  call       ""int int?.GetValueOrDefault()""
    IL_00f2:  stloc.s    V_5
    IL_00f4:  ldloca.s   V_4
    IL_00f6:  call       ""bool int?.HasValue.get""
    IL_00fb:  brtrue.s   IL_011c
    IL_00fd:  ldc.i4.1
    IL_00fe:  stloc.s    V_5
    IL_0100:  ldarg.0
    IL_0101:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0106:  ldloc.3
    IL_0107:  ldloc.s    V_5
    IL_0109:  newobj     ""int?..ctor(int)""
    IL_010e:  dup
    IL_010f:  stloc.s    V_7
    IL_0111:  constrained. ""T""
    IL_0117:  callvirt   ""void IMoveable.this[int].set""
    IL_011c:  leave.s    IL_0137
  }
  catch System.Exception
  {
    IL_011e:  stloc.s    V_8
    IL_0120:  ldarg.0
    IL_0121:  ldc.i4.s   -2
    IL_0123:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0128:  ldarg.0
    IL_0129:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_012e:  ldloc.s    V_8
    IL_0130:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0135:  leave.s    IL_014a
  }
  IL_0137:  ldarg.0
  IL_0138:  ldc.i4.s   -2
  IL_013a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_013f:  ldarg.0
  IL_0140:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0145:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_014a:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Value()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[1] += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[1] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       40 (0x28)
  .maxstack  4
  .locals init (T& V_0,
                T V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_1
  IL_0004:  stloc.0
  IL_0005:  ldloc.0
  IL_0006:  ldc.i4.1
  IL_0007:  ldloc.0
  IL_0008:  ldc.i4.1
  IL_0009:  constrained. ""T""
  IL_000f:  callvirt   ""int IMoveable.this[int].get""
  IL_0014:  ldarga.s   V_0
  IL_0016:  call       ""int Program.GetOffset<T>(ref T)""
  IL_001b:  add
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""void IMoveable.this[int].set""
  IL_0027:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       67 (0x43)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                T V_3)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldloc.0
  IL_0021:  ldc.i4.1
  IL_0022:  ldloc.0
  IL_0023:  ldc.i4.1
  IL_0024:  constrained. ""T""
  IL_002a:  callvirt   ""int IMoveable.this[int].get""
  IL_002f:  ldarga.s   V_0
  IL_0031:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0036:  add
  IL_0037:  constrained. ""T""
  IL_003d:  callvirt   ""void IMoveable.this[int].set""
  IL_0042:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Value()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[1] += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[1] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       38 (0x26)
  .maxstack  4
  .locals init (T& V_0)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldloc.0
  IL_0004:  ldc.i4.1
  IL_0005:  ldloc.0
  IL_0006:  ldc.i4.1
  IL_0007:  constrained. ""T""
  IL_000d:  callvirt   ""int IMoveable.this[int].get""
  IL_0012:  ldarga.s   V_0
  IL_0014:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0019:  add
  IL_001a:  constrained. ""T""
  IL_0020:  callvirt   ""void IMoveable.this[int].set""
  IL_0025:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Value_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[1] += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[1] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       44 (0x2c)
  .maxstack  4
  .locals init (T& V_0,
                T V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.1
  IL_0007:  ldloca.s   V_1
  IL_0009:  stloc.0
  IL_000a:  ldloc.0
  IL_000b:  ldc.i4.1
  IL_000c:  ldloc.0
  IL_000d:  ldc.i4.1
  IL_000e:  constrained. ""T""
  IL_0014:  callvirt   ""int IMoveable.this[int].get""
  IL_0019:  ldarg.0
  IL_001a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_001f:  add
  IL_0020:  constrained. ""T""
  IL_0026:  callvirt   ""void IMoveable.this[int].set""
  IL_002b:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       65 (0x41)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                T V_3)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_3
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.3
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_001d
  IL_0012:  ldloc.2
  IL_0013:  ldobj      ""T""
  IL_0018:  stloc.1
  IL_0019:  ldloca.s   V_1
  IL_001b:  br.s       IL_001e
  IL_001d:  ldloc.2
  IL_001e:  stloc.0
  IL_001f:  ldloc.0
  IL_0020:  ldc.i4.1
  IL_0021:  ldloc.0
  IL_0022:  ldc.i4.1
  IL_0023:  constrained. ""T""
  IL_0029:  callvirt   ""int IMoveable.this[int].get""
  IL_002e:  ldarg.0
  IL_002f:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0034:  add
  IL_0035:  constrained. ""T""
  IL_003b:  callvirt   ""void IMoveable.this[int].set""
  IL_0040:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Value_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[1] += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[1] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       36 (0x24)
  .maxstack  4
  .locals init (T& V_0)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  ldc.i4.1
  IL_0004:  ldloc.0
  IL_0005:  ldc.i4.1
  IL_0006:  constrained. ""T""
  IL_000c:  callvirt   ""int IMoveable.this[int].get""
  IL_0011:  ldarg.0
  IL_0012:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0017:  add
  IL_0018:  constrained. ""T""
  IL_001e:  callvirt   ""void IMoveable.this[int].set""
  IL_0023:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_Value_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[1] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[1] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      237 (0xed)
  .maxstack  4
  .locals init (int V_0,
                T& V_1,
                T V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0074
    IL_000a:  ldarg.0
    IL_000b:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  stloc.2
    IL_0011:  ldloca.s   V_2
    IL_0013:  stloc.1
    IL_0014:  ldarg.0
    IL_0015:  ldloc.1
    IL_0016:  ldobj      ""T""
    IL_001b:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0020:  ldarg.0
    IL_0021:  ldloc.1
    IL_0022:  ldc.i4.1
    IL_0023:  constrained. ""T""
    IL_0029:  callvirt   ""int IMoveable.this[int].get""
    IL_002e:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0033:  ldarg.0
    IL_0034:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0039:  call       ""int Program.GetOffset<T>(ref T)""
    IL_003e:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0043:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0048:  stloc.s    V_4
    IL_004a:  ldloca.s   V_4
    IL_004c:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0051:  brtrue.s   IL_0091
    IL_0053:  ldarg.0
    IL_0054:  ldc.i4.0
    IL_0055:  dup
    IL_0056:  stloc.0
    IL_0057:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_005c:  ldarg.0
    IL_005d:  ldloc.s    V_4
    IL_005f:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0064:  ldarg.0
    IL_0065:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_006a:  ldloca.s   V_4
    IL_006c:  ldarg.0
    IL_006d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0072:  leave.s    IL_00ec
    IL_0074:  ldarg.0
    IL_0075:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007a:  stloc.s    V_4
    IL_007c:  ldarg.0
    IL_007d:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0082:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0088:  ldarg.0
    IL_0089:  ldc.i4.m1
    IL_008a:  dup
    IL_008b:  stloc.0
    IL_008c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0091:  ldloca.s   V_4
    IL_0093:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0098:  stloc.3
    IL_0099:  ldarg.0
    IL_009a:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_009f:  box        ""T""
    IL_00a4:  ldc.i4.1
    IL_00a5:  ldarg.0
    IL_00a6:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00ab:  ldloc.3
    IL_00ac:  add
    IL_00ad:  callvirt   ""void IMoveable.this[int].set""
    IL_00b2:  ldarg.0
    IL_00b3:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b8:  initobj    ""T""
    IL_00be:  leave.s    IL_00d9
  }
  catch System.Exception
  {
    IL_00c0:  stloc.s    V_5
    IL_00c2:  ldarg.0
    IL_00c3:  ldc.i4.s   -2
    IL_00c5:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ca:  ldarg.0
    IL_00cb:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00d0:  ldloc.s    V_5
    IL_00d2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d7:  leave.s    IL_00ec
  }
  IL_00d9:  ldarg.0
  IL_00da:  ldc.i4.s   -2
  IL_00dc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00e1:  ldarg.0
  IL_00e2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00e7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ec:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      300 (0x12c)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_009b
    IL_000d:  ldloca.s   V_2
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.2
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldarg.0
    IL_002a:  ldloca.s   V_2
    IL_002c:  initobj    ""T""
    IL_0032:  ldloc.2
    IL_0033:  box        ""T""
    IL_0038:  brtrue.s   IL_0042
    IL_003a:  ldarg.0
    IL_003b:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0040:  br.s       IL_0048
    IL_0042:  ldarg.0
    IL_0043:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0048:  ldc.i4.1
    IL_0049:  constrained. ""T""
    IL_004f:  callvirt   ""int IMoveable.this[int].get""
    IL_0054:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0059:  ldarg.0
    IL_005a:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_005f:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0064:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0069:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_006e:  stloc.3
    IL_006f:  ldloca.s   V_3
    IL_0071:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0076:  brtrue.s   IL_00b7
    IL_0078:  ldarg.0
    IL_0079:  ldc.i4.0
    IL_007a:  dup
    IL_007b:  stloc.0
    IL_007c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0081:  ldarg.0
    IL_0082:  ldloc.3
    IL_0083:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0088:  ldarg.0
    IL_0089:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_008e:  ldloca.s   V_3
    IL_0090:  ldarg.0
    IL_0091:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0096:  leave      IL_012b
    IL_009b:  ldarg.0
    IL_009c:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00a1:  stloc.3
    IL_00a2:  ldarg.0
    IL_00a3:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00a8:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00ae:  ldarg.0
    IL_00af:  ldc.i4.m1
    IL_00b0:  dup
    IL_00b1:  stloc.0
    IL_00b2:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00b7:  ldloca.s   V_3
    IL_00b9:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00be:  stloc.1
    IL_00bf:  ldloca.s   V_2
    IL_00c1:  initobj    ""T""
    IL_00c7:  ldloc.2
    IL_00c8:  box        ""T""
    IL_00cd:  brtrue.s   IL_00d7
    IL_00cf:  ldarg.0
    IL_00d0:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00d5:  br.s       IL_00dd
    IL_00d7:  ldarg.0
    IL_00d8:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00dd:  ldc.i4.1
    IL_00de:  ldarg.0
    IL_00df:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00e4:  ldloc.1
    IL_00e5:  add
    IL_00e6:  constrained. ""T""
    IL_00ec:  callvirt   ""void IMoveable.this[int].set""
    IL_00f1:  ldarg.0
    IL_00f2:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f7:  initobj    ""T""
    IL_00fd:  leave.s    IL_0118
  }
  catch System.Exception
  {
    IL_00ff:  stloc.s    V_4
    IL_0101:  ldarg.0
    IL_0102:  ldc.i4.s   -2
    IL_0104:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0109:  ldarg.0
    IL_010a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_010f:  ldloc.s    V_4
    IL_0111:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0116:  leave.s    IL_012b
  }
  IL_0118:  ldarg.0
  IL_0119:  ldc.i4.s   -2
  IL_011b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0120:  ldarg.0
  IL_0121:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0126:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_012b:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_Value_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[1] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[1] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      204 (0xcc)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0061
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  ldc.i4.1
    IL_0012:  constrained. ""T""
    IL_0018:  callvirt   ""int IMoveable.this[int].get""
    IL_001d:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0022:  ldarg.0
    IL_0023:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0028:  call       ""int Program.GetOffset<T>(ref T)""
    IL_002d:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0032:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0037:  stloc.2
    IL_0038:  ldloca.s   V_2
    IL_003a:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003f:  brtrue.s   IL_007d
    IL_0041:  ldarg.0
    IL_0042:  ldc.i4.0
    IL_0043:  dup
    IL_0044:  stloc.0
    IL_0045:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_004a:  ldarg.0
    IL_004b:  ldloc.2
    IL_004c:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0051:  ldarg.0
    IL_0052:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0057:  ldloca.s   V_2
    IL_0059:  ldarg.0
    IL_005a:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_005f:  leave.s    IL_00cb
    IL_0061:  ldarg.0
    IL_0062:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0067:  stloc.2
    IL_0068:  ldarg.0
    IL_0069:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006e:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0074:  ldarg.0
    IL_0075:  ldc.i4.m1
    IL_0076:  dup
    IL_0077:  stloc.0
    IL_0078:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007d:  ldloca.s   V_2
    IL_007f:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0084:  stloc.1
    IL_0085:  ldarg.0
    IL_0086:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008b:  ldc.i4.1
    IL_008c:  ldarg.0
    IL_008d:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0092:  ldloc.1
    IL_0093:  add
    IL_0094:  constrained. ""T""
    IL_009a:  callvirt   ""void IMoveable.this[int].set""
    IL_009f:  leave.s    IL_00b8
  }
  catch System.Exception
  {
    IL_00a1:  stloc.3
    IL_00a2:  ldarg.0
    IL_00a3:  ldc.i4.s   -2
    IL_00a5:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00aa:  ldarg.0
    IL_00ab:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00b0:  ldloc.3
    IL_00b1:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00b6:  leave.s    IL_00cb
  }
  IL_00b8:  ldarg.0
  IL_00b9:  ldc.i4.s   -2
  IL_00bb:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00c0:  ldarg.0
  IL_00c1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00c6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00cb:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_IndexAndValue()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       48 (0x30)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_1
  IL_0004:  stloc.0
  IL_0005:  ldarga.s   V_0
  IL_0007:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000c:  stloc.2
  IL_000d:  ldloc.0
  IL_000e:  ldloc.2
  IL_000f:  ldloc.0
  IL_0010:  ldloc.2
  IL_0011:  constrained. ""T""
  IL_0017:  callvirt   ""int IMoveable.this[int].get""
  IL_001c:  ldarga.s   V_0
  IL_001e:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0023:  add
  IL_0024:  constrained. ""T""
  IL_002a:  callvirt   ""void IMoveable.this[int].set""
  IL_002f:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       76 (0x4c)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_4
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_4
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  ldloc.3
  IL_002b:  ldloc.0
  IL_002c:  ldloc.3
  IL_002d:  constrained. ""T""
  IL_0033:  callvirt   ""int IMoveable.this[int].get""
  IL_0038:  ldarga.s   V_0
  IL_003a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_003f:  add
  IL_0040:  constrained. ""T""
  IL_0046:  callvirt   ""void IMoveable.this[int].set""
  IL_004b:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_IndexAndValue()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       46 (0x2e)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  ldloc.1
  IL_000d:  ldloc.0
  IL_000e:  ldloc.1
  IL_000f:  constrained. ""T""
  IL_0015:  callvirt   ""int IMoveable.this[int].get""
  IL_001a:  ldarga.s   V_0
  IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0021:  add
  IL_0022:  constrained. ""T""
  IL_0028:  callvirt   ""void IMoveable.this[int].set""
  IL_002d:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_IndexAndValue_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       51 (0x33)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.1
  IL_0007:  ldloca.s   V_1
  IL_0009:  stloc.0
  IL_000a:  ldarg.0
  IL_000b:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0010:  stloc.2
  IL_0011:  ldloc.0
  IL_0012:  ldloc.2
  IL_0013:  ldloc.0
  IL_0014:  ldloc.2
  IL_0015:  constrained. ""T""
  IL_001b:  callvirt   ""int IMoveable.this[int].get""
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  add
  IL_0027:  constrained. ""T""
  IL_002d:  callvirt   ""void IMoveable.this[int].set""
  IL_0032:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       73 (0x49)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_4
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_4
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  ldloc.3
  IL_0029:  ldloc.0
  IL_002a:  ldloc.3
  IL_002b:  constrained. ""T""
  IL_0031:  callvirt   ""int IMoveable.this[int].get""
  IL_0036:  ldarg.0
  IL_0037:  call       ""int Program.GetOffset<T>(ref T)""
  IL_003c:  add
  IL_003d:  constrained. ""T""
  IL_0043:  callvirt   ""void IMoveable.this[int].set""
  IL_0048:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_IndexAndValue_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       43 (0x2b)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  ldloc.1
  IL_000b:  ldloc.0
  IL_000c:  ldloc.1
  IL_000d:  constrained. ""T""
  IL_0013:  callvirt   ""int IMoveable.this[int].get""
  IL_0018:  ldarg.0
  IL_0019:  call       ""int Program.GetOffset<T>(ref T)""
  IL_001e:  add
  IL_001f:  constrained. ""T""
  IL_0025:  callvirt   ""void IMoveable.this[int].set""
  IL_002a:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_IndexAndValue_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      263 (0x107)
  .maxstack  4
  .locals init (int V_0,
                T& V_1,
                T V_2,
                int V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0087
    IL_000a:  ldarg.0
    IL_000b:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  stloc.2
    IL_0011:  ldloca.s   V_2
    IL_0013:  stloc.1
    IL_0014:  ldarg.0
    IL_0015:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001a:  call       ""int Program.GetOffset<T>(ref T)""
    IL_001f:  stloc.3
    IL_0020:  ldarg.0
    IL_0021:  ldloc.1
    IL_0022:  ldobj      ""T""
    IL_0027:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_002c:  ldarg.0
    IL_002d:  ldloc.3
    IL_002e:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0033:  ldarg.0
    IL_0034:  ldloc.1
    IL_0035:  ldloc.3
    IL_0036:  constrained. ""T""
    IL_003c:  callvirt   ""int IMoveable.this[int].get""
    IL_0041:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_0046:  ldarg.0
    IL_0047:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_004c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0051:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0056:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_005b:  stloc.s    V_5
    IL_005d:  ldloca.s   V_5
    IL_005f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0064:  brtrue.s   IL_00a4
    IL_0066:  ldarg.0
    IL_0067:  ldc.i4.0
    IL_0068:  dup
    IL_0069:  stloc.0
    IL_006a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_006f:  ldarg.0
    IL_0070:  ldloc.s    V_5
    IL_0072:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0077:  ldarg.0
    IL_0078:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_007d:  ldloca.s   V_5
    IL_007f:  ldarg.0
    IL_0080:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0085:  leave.s    IL_0106
    IL_0087:  ldarg.0
    IL_0088:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_008d:  stloc.s    V_5
    IL_008f:  ldarg.0
    IL_0090:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0095:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_009b:  ldarg.0
    IL_009c:  ldc.i4.m1
    IL_009d:  dup
    IL_009e:  stloc.0
    IL_009f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00a4:  ldloca.s   V_5
    IL_00a6:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00ab:  stloc.s    V_4
    IL_00ad:  ldarg.0
    IL_00ae:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b3:  box        ""T""
    IL_00b8:  ldarg.0
    IL_00b9:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00be:  ldarg.0
    IL_00bf:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_00c4:  ldloc.s    V_4
    IL_00c6:  add
    IL_00c7:  callvirt   ""void IMoveable.this[int].set""
    IL_00cc:  ldarg.0
    IL_00cd:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00d2:  initobj    ""T""
    IL_00d8:  leave.s    IL_00f3
  }
  catch System.Exception
  {
    IL_00da:  stloc.s    V_6
    IL_00dc:  ldarg.0
    IL_00dd:  ldc.i4.s   -2
    IL_00df:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e4:  ldarg.0
    IL_00e5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00ea:  ldloc.s    V_6
    IL_00ec:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00f1:  leave.s    IL_0106
  }
  IL_00f3:  ldarg.0
  IL_00f4:  ldc.i4.s   -2
  IL_00f6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00fb:  ldarg.0
  IL_00fc:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0101:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0106:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      327 (0x147)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00b0
    IL_000d:  ldloca.s   V_3
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.3
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldarg.0
    IL_002a:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002f:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0034:  stloc.1
    IL_0035:  ldarg.0
    IL_0036:  ldloc.1
    IL_0037:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_003c:  ldarg.0
    IL_003d:  ldloca.s   V_3
    IL_003f:  initobj    ""T""
    IL_0045:  ldloc.3
    IL_0046:  box        ""T""
    IL_004b:  brtrue.s   IL_0055
    IL_004d:  ldarg.0
    IL_004e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0053:  br.s       IL_005b
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_005b:  ldloc.1
    IL_005c:  constrained. ""T""
    IL_0062:  callvirt   ""int IMoveable.this[int].get""
    IL_0067:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_006c:  ldarg.0
    IL_006d:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0072:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0077:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_007c:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0081:  stloc.s    V_4
    IL_0083:  ldloca.s   V_4
    IL_0085:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_008a:  brtrue.s   IL_00cd
    IL_008c:  ldarg.0
    IL_008d:  ldc.i4.0
    IL_008e:  dup
    IL_008f:  stloc.0
    IL_0090:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0095:  ldarg.0
    IL_0096:  ldloc.s    V_4
    IL_0098:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_009d:  ldarg.0
    IL_009e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00a3:  ldloca.s   V_4
    IL_00a5:  ldarg.0
    IL_00a6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00ab:  leave      IL_0146
    IL_00b0:  ldarg.0
    IL_00b1:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00b6:  stloc.s    V_4
    IL_00b8:  ldarg.0
    IL_00b9:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00be:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00c4:  ldarg.0
    IL_00c5:  ldc.i4.m1
    IL_00c6:  dup
    IL_00c7:  stloc.0
    IL_00c8:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00cd:  ldloca.s   V_4
    IL_00cf:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00d4:  stloc.2
    IL_00d5:  ldloca.s   V_3
    IL_00d7:  initobj    ""T""
    IL_00dd:  ldloc.3
    IL_00de:  box        ""T""
    IL_00e3:  brtrue.s   IL_00ed
    IL_00e5:  ldarg.0
    IL_00e6:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00eb:  br.s       IL_00f3
    IL_00ed:  ldarg.0
    IL_00ee:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00f3:  ldarg.0
    IL_00f4:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00f9:  ldarg.0
    IL_00fa:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_00ff:  ldloc.2
    IL_0100:  add
    IL_0101:  constrained. ""T""
    IL_0107:  callvirt   ""void IMoveable.this[int].set""
    IL_010c:  ldarg.0
    IL_010d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0112:  initobj    ""T""
    IL_0118:  leave.s    IL_0133
  }
  catch System.Exception
  {
    IL_011a:  stloc.s    V_5
    IL_011c:  ldarg.0
    IL_011d:  ldc.i4.s   -2
    IL_011f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0124:  ldarg.0
    IL_0125:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_012a:  ldloc.s    V_5
    IL_012c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0131:  leave.s    IL_0146
  }
  IL_0133:  ldarg.0
  IL_0134:  ldc.i4.s   -2
  IL_0136:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_013b:  ldarg.0
  IL_013c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0141:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0146:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_IndexAndValue_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      230 (0xe6)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0074
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  stloc.1
    IL_0016:  ldarg.0
    IL_0017:  ldloc.1
    IL_0018:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0024:  ldloc.1
    IL_0025:  constrained. ""T""
    IL_002b:  callvirt   ""int IMoveable.this[int].get""
    IL_0030:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0035:  ldarg.0
    IL_0036:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_003b:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0040:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0045:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_004a:  stloc.3
    IL_004b:  ldloca.s   V_3
    IL_004d:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0052:  brtrue.s   IL_0090
    IL_0054:  ldarg.0
    IL_0055:  ldc.i4.0
    IL_0056:  dup
    IL_0057:  stloc.0
    IL_0058:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_005d:  ldarg.0
    IL_005e:  ldloc.3
    IL_005f:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0064:  ldarg.0
    IL_0065:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_006a:  ldloca.s   V_3
    IL_006c:  ldarg.0
    IL_006d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0072:  leave.s    IL_00e5
    IL_0074:  ldarg.0
    IL_0075:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007a:  stloc.3
    IL_007b:  ldarg.0
    IL_007c:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0081:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0087:  ldarg.0
    IL_0088:  ldc.i4.m1
    IL_0089:  dup
    IL_008a:  stloc.0
    IL_008b:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0090:  ldloca.s   V_3
    IL_0092:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0097:  stloc.2
    IL_0098:  ldarg.0
    IL_0099:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_009e:  ldarg.0
    IL_009f:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a4:  ldarg.0
    IL_00a5:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00aa:  ldloc.2
    IL_00ab:  add
    IL_00ac:  constrained. ""T""
    IL_00b2:  callvirt   ""void IMoveable.this[int].set""
    IL_00b7:  leave.s    IL_00d2
  }
  catch System.Exception
  {
    IL_00b9:  stloc.s    V_4
    IL_00bb:  ldarg.0
    IL_00bc:  ldc.i4.s   -2
    IL_00be:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c3:  ldarg.0
    IL_00c4:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00c9:  ldloc.s    V_4
    IL_00cb:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d0:  leave.s    IL_00e5
  }
  IL_00d2:  ldarg.0
  IL_00d3:  ldc.i4.s   -2
  IL_00d5:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00da:  ldarg.0
  IL_00db:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00e0:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00e5:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_IndexAndValue_Async_03()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += GetOffset(ref item);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      227 (0xe3)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0058
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.2
    IL_002c:  ldloca.s   V_2
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0074
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.2
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_2
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0053:  leave      IL_00e2
    IL_0058:  ldarg.0
    IL_0059:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005e:  stloc.2
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0065:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006b:  ldarg.0
    IL_006c:  ldc.i4.m1
    IL_006d:  dup
    IL_006e:  stloc.0
    IL_006f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0074:  ldloca.s   V_2
    IL_0076:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007b:  stloc.1
    IL_007c:  ldarg.0
    IL_007d:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0082:  box        ""T""
    IL_0087:  ldloc.1
    IL_0088:  ldarg.0
    IL_0089:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008e:  box        ""T""
    IL_0093:  ldloc.1
    IL_0094:  callvirt   ""int IMoveable.this[int].get""
    IL_0099:  ldarg.0
    IL_009a:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_009f:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00a4:  add
    IL_00a5:  callvirt   ""void IMoveable.this[int].set""
    IL_00aa:  ldarg.0
    IL_00ab:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b0:  initobj    ""T""
    IL_00b6:  leave.s    IL_00cf
  }
  catch System.Exception
  {
    IL_00b8:  stloc.3
    IL_00b9:  ldarg.0
    IL_00ba:  ldc.i4.s   -2
    IL_00bc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c1:  ldarg.0
    IL_00c2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00c7:  ldloc.3
    IL_00c8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00cd:  leave.s    IL_00e2
  }
  IL_00cf:  ldarg.0
  IL_00d0:  ldc.i4.s   -2
  IL_00d2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00d7:  ldarg.0
  IL_00d8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00dd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00e2:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      295 (0x127)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0068
    IL_000a:  ldloca.s   V_2
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.2
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.3
    IL_003c:  ldloca.s   V_3
    IL_003e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0043:  brtrue.s   IL_0084
    IL_0045:  ldarg.0
    IL_0046:  ldc.i4.0
    IL_0047:  dup
    IL_0048:  stloc.0
    IL_0049:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_004e:  ldarg.0
    IL_004f:  ldloc.3
    IL_0050:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005b:  ldloca.s   V_3
    IL_005d:  ldarg.0
    IL_005e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0063:  leave      IL_0126
    IL_0068:  ldarg.0
    IL_0069:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_006e:  stloc.3
    IL_006f:  ldarg.0
    IL_0070:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0075:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007b:  ldarg.0
    IL_007c:  ldc.i4.m1
    IL_007d:  dup
    IL_007e:  stloc.0
    IL_007f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0084:  ldloca.s   V_3
    IL_0086:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008b:  stloc.1
    IL_008c:  ldloca.s   V_2
    IL_008e:  initobj    ""T""
    IL_0094:  ldloc.2
    IL_0095:  box        ""T""
    IL_009a:  brtrue.s   IL_00a4
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a2:  br.s       IL_00aa
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00aa:  ldloc.1
    IL_00ab:  ldloca.s   V_2
    IL_00ad:  initobj    ""T""
    IL_00b3:  ldloc.2
    IL_00b4:  box        ""T""
    IL_00b9:  brtrue.s   IL_00c3
    IL_00bb:  ldarg.0
    IL_00bc:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00c1:  br.s       IL_00c9
    IL_00c3:  ldarg.0
    IL_00c4:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00c9:  ldloc.1
    IL_00ca:  constrained. ""T""
    IL_00d0:  callvirt   ""int IMoveable.this[int].get""
    IL_00d5:  ldarg.0
    IL_00d6:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00db:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00e0:  add
    IL_00e1:  constrained. ""T""
    IL_00e7:  callvirt   ""void IMoveable.this[int].set""
    IL_00ec:  ldarg.0
    IL_00ed:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f2:  initobj    ""T""
    IL_00f8:  leave.s    IL_0113
  }
  catch System.Exception
  {
    IL_00fa:  stloc.s    V_4
    IL_00fc:  ldarg.0
    IL_00fd:  ldc.i4.s   -2
    IL_00ff:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0104:  ldarg.0
    IL_0105:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_010a:  ldloc.s    V_4
    IL_010c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0111:  leave.s    IL_0126
  }
  IL_0113:  ldarg.0
  IL_0114:  ldc.i4.s   -2
  IL_0116:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_011b:  ldarg.0
  IL_011c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0121:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0126:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_IndexAndValue_Async_03()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += GetOffset(ref item);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      205 (0xcd)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004c
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.2
    IL_0020:  ldloca.s   V_2
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0068
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.2
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_2
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0047:  leave      IL_00cc
    IL_004c:  ldarg.0
    IL_004d:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0052:  stloc.2
    IL_0053:  ldarg.0
    IL_0054:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0059:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005f:  ldarg.0
    IL_0060:  ldc.i4.m1
    IL_0061:  dup
    IL_0062:  stloc.0
    IL_0063:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0068:  ldloca.s   V_2
    IL_006a:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006f:  stloc.1
    IL_0070:  ldarg.0
    IL_0071:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0076:  ldloc.1
    IL_0077:  ldarg.0
    IL_0078:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_007d:  ldloc.1
    IL_007e:  constrained. ""T""
    IL_0084:  callvirt   ""int IMoveable.this[int].get""
    IL_0089:  ldarg.0
    IL_008a:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008f:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0094:  add
    IL_0095:  constrained. ""T""
    IL_009b:  callvirt   ""void IMoveable.this[int].set""
    IL_00a0:  leave.s    IL_00b9
  }
  catch System.Exception
  {
    IL_00a2:  stloc.3
    IL_00a3:  ldarg.0
    IL_00a4:  ldc.i4.s   -2
    IL_00a6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ab:  ldarg.0
    IL_00ac:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00b1:  ldloc.3
    IL_00b2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00b7:  leave.s    IL_00cc
  }
  IL_00b9:  ldarg.0
  IL_00ba:  ldc.i4.s   -2
  IL_00bc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00c1:  ldarg.0
  IL_00c2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00c7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00cc:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Class_IndexAndValue_Async_04()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      376 (0x178)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_005f
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00ef
    IL_0011:  ldarg.0
    IL_0012:  ldarg.0
    IL_0013:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0018:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_001d:  ldarg.0
    IL_001e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0028:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_002d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0032:  stloc.3
    IL_0033:  ldloca.s   V_3
    IL_0035:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003a:  brtrue.s   IL_007b
    IL_003c:  ldarg.0
    IL_003d:  ldc.i4.0
    IL_003e:  dup
    IL_003f:  stloc.0
    IL_0040:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0045:  ldarg.0
    IL_0046:  ldloc.3
    IL_0047:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004c:  ldarg.0
    IL_004d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0052:  ldloca.s   V_3
    IL_0054:  ldarg.0
    IL_0055:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_005a:  leave      IL_0177
    IL_005f:  ldarg.0
    IL_0060:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0065:  stloc.3
    IL_0066:  ldarg.0
    IL_0067:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0072:  ldarg.0
    IL_0073:  ldc.i4.m1
    IL_0074:  dup
    IL_0075:  stloc.0
    IL_0076:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007b:  ldloca.s   V_3
    IL_007d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0082:  stloc.1
    IL_0083:  ldarg.0
    IL_0084:  ldarg.0
    IL_0085:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008a:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_008f:  ldarg.0
    IL_0090:  ldloc.1
    IL_0091:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_0096:  ldarg.0
    IL_0097:  ldarg.0
    IL_0098:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_009d:  box        ""T""
    IL_00a2:  ldloc.1
    IL_00a3:  callvirt   ""int IMoveable.this[int].get""
    IL_00a8:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap4""
    IL_00ad:  ldarg.0
    IL_00ae:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b3:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00b8:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00bd:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00c2:  stloc.3
    IL_00c3:  ldloca.s   V_3
    IL_00c5:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00ca:  brtrue.s   IL_010b
    IL_00cc:  ldarg.0
    IL_00cd:  ldc.i4.1
    IL_00ce:  dup
    IL_00cf:  stloc.0
    IL_00d0:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00d5:  ldarg.0
    IL_00d6:  ldloc.3
    IL_00d7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00dc:  ldarg.0
    IL_00dd:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e2:  ldloca.s   V_3
    IL_00e4:  ldarg.0
    IL_00e5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00ea:  leave      IL_0177
    IL_00ef:  ldarg.0
    IL_00f0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00f5:  stloc.3
    IL_00f6:  ldarg.0
    IL_00f7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00fc:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0102:  ldarg.0
    IL_0103:  ldc.i4.m1
    IL_0104:  dup
    IL_0105:  stloc.0
    IL_0106:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_010b:  ldloca.s   V_3
    IL_010d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0112:  stloc.2
    IL_0113:  ldarg.0
    IL_0114:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0119:  box        ""T""
    IL_011e:  ldarg.0
    IL_011f:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_0124:  ldarg.0
    IL_0125:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap4""
    IL_012a:  ldloc.2
    IL_012b:  add
    IL_012c:  callvirt   ""void IMoveable.this[int].set""
    IL_0131:  ldarg.0
    IL_0132:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0137:  initobj    ""T""
    IL_013d:  ldarg.0
    IL_013e:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0143:  initobj    ""T""
    IL_0149:  leave.s    IL_0164
  }
  catch System.Exception
  {
    IL_014b:  stloc.s    V_4
    IL_014d:  ldarg.0
    IL_014e:  ldc.i4.s   -2
    IL_0150:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0155:  ldarg.0
    IL_0156:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_015b:  ldloc.s    V_4
    IL_015d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0162:  leave.s    IL_0177
  }
  IL_0164:  ldarg.0
  IL_0165:  ldc.i4.s   -2
  IL_0167:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_016c:  ldarg.0
  IL_016d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0172:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0177:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      424 (0x1a8)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0071
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_0111
    IL_0011:  ldloca.s   V_3
    IL_0013:  initobj    ""T""
    IL_0019:  ldloc.3
    IL_001a:  box        ""T""
    IL_001f:  brtrue.s   IL_002d
    IL_0021:  ldarg.0
    IL_0022:  ldarg.0
    IL_0023:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0028:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_002d:  ldarg.0
    IL_002e:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0033:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0038:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_003d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0042:  stloc.s    V_4
    IL_0044:  ldloca.s   V_4
    IL_0046:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_004b:  brtrue.s   IL_008e
    IL_004d:  ldarg.0
    IL_004e:  ldc.i4.0
    IL_004f:  dup
    IL_0050:  stloc.0
    IL_0051:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0056:  ldarg.0
    IL_0057:  ldloc.s    V_4
    IL_0059:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_005e:  ldarg.0
    IL_005f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0064:  ldloca.s   V_4
    IL_0066:  ldarg.0
    IL_0067:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_006c:  leave      IL_01a7
    IL_0071:  ldarg.0
    IL_0072:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0077:  stloc.s    V_4
    IL_0079:  ldarg.0
    IL_007a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_007f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0085:  ldarg.0
    IL_0086:  ldc.i4.m1
    IL_0087:  dup
    IL_0088:  stloc.0
    IL_0089:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_008e:  ldloca.s   V_4
    IL_0090:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0095:  stloc.1
    IL_0096:  ldarg.0
    IL_0097:  ldloc.1
    IL_0098:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_009d:  ldarg.0
    IL_009e:  ldloca.s   V_3
    IL_00a0:  initobj    ""T""
    IL_00a6:  ldloc.3
    IL_00a7:  box        ""T""
    IL_00ac:  brtrue.s   IL_00b6
    IL_00ae:  ldarg.0
    IL_00af:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00b4:  br.s       IL_00bc
    IL_00b6:  ldarg.0
    IL_00b7:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00bc:  ldloc.1
    IL_00bd:  constrained. ""T""
    IL_00c3:  callvirt   ""int IMoveable.this[int].get""
    IL_00c8:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_00cd:  ldarg.0
    IL_00ce:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00d3:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00d8:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00dd:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00e2:  stloc.s    V_4
    IL_00e4:  ldloca.s   V_4
    IL_00e6:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00eb:  brtrue.s   IL_012e
    IL_00ed:  ldarg.0
    IL_00ee:  ldc.i4.1
    IL_00ef:  dup
    IL_00f0:  stloc.0
    IL_00f1:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00f6:  ldarg.0
    IL_00f7:  ldloc.s    V_4
    IL_00f9:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00fe:  ldarg.0
    IL_00ff:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0104:  ldloca.s   V_4
    IL_0106:  ldarg.0
    IL_0107:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_010c:  leave      IL_01a7
    IL_0111:  ldarg.0
    IL_0112:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0117:  stloc.s    V_4
    IL_0119:  ldarg.0
    IL_011a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_011f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0125:  ldarg.0
    IL_0126:  ldc.i4.m1
    IL_0127:  dup
    IL_0128:  stloc.0
    IL_0129:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_012e:  ldloca.s   V_4
    IL_0130:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0135:  stloc.2
    IL_0136:  ldloca.s   V_3
    IL_0138:  initobj    ""T""
    IL_013e:  ldloc.3
    IL_013f:  box        ""T""
    IL_0144:  brtrue.s   IL_014e
    IL_0146:  ldarg.0
    IL_0147:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_014c:  br.s       IL_0154
    IL_014e:  ldarg.0
    IL_014f:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0154:  ldarg.0
    IL_0155:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_015a:  ldarg.0
    IL_015b:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0160:  ldloc.2
    IL_0161:  add
    IL_0162:  constrained. ""T""
    IL_0168:  callvirt   ""void IMoveable.this[int].set""
    IL_016d:  ldarg.0
    IL_016e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0173:  initobj    ""T""
    IL_0179:  leave.s    IL_0194
  }
  catch System.Exception
  {
    IL_017b:  stloc.s    V_5
    IL_017d:  ldarg.0
    IL_017e:  ldc.i4.s   -2
    IL_0180:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0185:  ldarg.0
    IL_0186:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_018b:  ldloc.s    V_5
    IL_018d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0192:  leave.s    IL_01a7
  }
  IL_0194:  ldarg.0
  IL_0195:  ldc.i4.s   -2
  IL_0197:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_019c:  ldarg.0
  IL_019d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_01a2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_01a7:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_Indexer_Struct_IndexAndValue_Async_04()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      327 (0x147)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0053
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00d5
    IL_0011:  ldarg.0
    IL_0012:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0017:  call       ""int Program.GetOffset<T>(ref T)""
    IL_001c:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0021:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0026:  stloc.3
    IL_0027:  ldloca.s   V_3
    IL_0029:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_002e:  brtrue.s   IL_006f
    IL_0030:  ldarg.0
    IL_0031:  ldc.i4.0
    IL_0032:  dup
    IL_0033:  stloc.0
    IL_0034:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0039:  ldarg.0
    IL_003a:  ldloc.3
    IL_003b:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0040:  ldarg.0
    IL_0041:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0046:  ldloca.s   V_3
    IL_0048:  ldarg.0
    IL_0049:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_004e:  leave      IL_0146
    IL_0053:  ldarg.0
    IL_0054:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0059:  stloc.3
    IL_005a:  ldarg.0
    IL_005b:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0060:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0066:  ldarg.0
    IL_0067:  ldc.i4.m1
    IL_0068:  dup
    IL_0069:  stloc.0
    IL_006a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_006f:  ldloca.s   V_3
    IL_0071:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0076:  stloc.1
    IL_0077:  ldarg.0
    IL_0078:  ldloc.1
    IL_0079:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_007e:  ldarg.0
    IL_007f:  ldarg.0
    IL_0080:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0085:  ldloc.1
    IL_0086:  constrained. ""T""
    IL_008c:  callvirt   ""int IMoveable.this[int].get""
    IL_0091:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0096:  ldarg.0
    IL_0097:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_009c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00a1:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00a6:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00ab:  stloc.3
    IL_00ac:  ldloca.s   V_3
    IL_00ae:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00b3:  brtrue.s   IL_00f1
    IL_00b5:  ldarg.0
    IL_00b6:  ldc.i4.1
    IL_00b7:  dup
    IL_00b8:  stloc.0
    IL_00b9:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00be:  ldarg.0
    IL_00bf:  ldloc.3
    IL_00c0:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00c5:  ldarg.0
    IL_00c6:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00cb:  ldloca.s   V_3
    IL_00cd:  ldarg.0
    IL_00ce:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00d3:  leave.s    IL_0146
    IL_00d5:  ldarg.0
    IL_00d6:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00db:  stloc.3
    IL_00dc:  ldarg.0
    IL_00dd:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00e2:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00e8:  ldarg.0
    IL_00e9:  ldc.i4.m1
    IL_00ea:  dup
    IL_00eb:  stloc.0
    IL_00ec:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00f1:  ldloca.s   V_3
    IL_00f3:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00f8:  stloc.2
    IL_00f9:  ldarg.0
    IL_00fa:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00ff:  ldarg.0
    IL_0100:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0105:  ldarg.0
    IL_0106:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_010b:  ldloc.2
    IL_010c:  add
    IL_010d:  constrained. ""T""
    IL_0113:  callvirt   ""void IMoveable.this[int].set""
    IL_0118:  leave.s    IL_0133
  }
  catch System.Exception
  {
    IL_011a:  stloc.s    V_4
    IL_011c:  ldarg.0
    IL_011d:  ldc.i4.s   -2
    IL_011f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0124:  ldarg.0
    IL_0125:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_012a:  ldloc.s    V_4
    IL_012c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0131:  leave.s    IL_0146
  }
  IL_0133:  ldarg.0
  IL_0134:  ldc.i4.s   -2
  IL_0136:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_013b:  ldarg.0
  IL_013c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0141:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0146:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_Value()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[1] ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[1] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       68 (0x44)
  .maxstack  4
  .locals init (T& V_0,
              T V_1,
              int? V_2,
              int V_3,
              int? V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_1
  IL_0004:  stloc.0
  IL_0005:  ldloc.0
  IL_0006:  ldc.i4.1
  IL_0007:  constrained. ""T""
  IL_000d:  callvirt   ""int? IMoveable.this[int].get""
  IL_0012:  stloc.2
  IL_0013:  ldloca.s   V_2
  IL_0015:  call       ""int int?.GetValueOrDefault()""
  IL_001a:  stloc.3
  IL_001b:  ldloca.s   V_2
  IL_001d:  call       ""bool int?.HasValue.get""
  IL_0022:  brtrue.s   IL_0043
  IL_0024:  ldarga.s   V_0
  IL_0026:  call       ""int Program.GetOffset<T>(ref T)""
  IL_002b:  stloc.3
  IL_002c:  ldloc.0
  IL_002d:  ldc.i4.1
  IL_002e:  ldloca.s   V_4
  IL_0030:  ldloc.3
  IL_0031:  call       ""int?..ctor(int)""
  IL_0036:  ldloc.s    V_4
  IL_0038:  constrained. ""T""
  IL_003e:  callvirt   ""void IMoveable.this[int].set""
  IL_0043:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       99 (0x63)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int? V_3,
                int V_4,
                T V_5,
                int? V_6)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_5
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_5
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldloc.0
  IL_0022:  ldc.i4.1
  IL_0023:  constrained. ""T""
  IL_0029:  callvirt   ""int? IMoveable.this[int].get""
  IL_002e:  stloc.3
  IL_002f:  ldloca.s   V_3
  IL_0031:  call       ""int int?.GetValueOrDefault()""
  IL_0036:  stloc.s    V_4
  IL_0038:  ldloca.s   V_3
  IL_003a:  call       ""bool int?.HasValue.get""
  IL_003f:  brtrue.s   IL_0062
  IL_0041:  ldarga.s   V_0
  IL_0043:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0048:  stloc.s    V_4
  IL_004a:  ldloc.0
  IL_004b:  ldc.i4.1
  IL_004c:  ldloca.s   V_6
  IL_004e:  ldloc.s    V_4
  IL_0050:  call       ""int?..ctor(int)""
  IL_0055:  ldloc.s    V_6
  IL_0057:  constrained. ""T""
  IL_005d:  callvirt   ""void IMoveable.this[int].set""
  IL_0062:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_Value()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[1] ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[1] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       65 (0x41)
  .maxstack  4
  .locals init (T& V_0,
                int? V_1,
                int V_2,
                int? V_3)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldloc.0
  IL_0004:  ldc.i4.1
  IL_0005:  constrained. ""T""
  IL_000b:  callvirt   ""int? IMoveable.this[int].get""
  IL_0010:  stloc.1
  IL_0011:  ldloca.s   V_1
  IL_0013:  call       ""int int?.GetValueOrDefault()""
  IL_0018:  stloc.2
  IL_0019:  ldloca.s   V_1
  IL_001b:  call       ""bool int?.HasValue.get""
  IL_0020:  brtrue.s   IL_0040
  IL_0022:  ldarga.s   V_0
  IL_0024:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0029:  stloc.2
  IL_002a:  ldloc.0
  IL_002b:  ldc.i4.1
  IL_002c:  ldloca.s   V_3
  IL_002e:  ldloc.2
  IL_002f:  call       ""int?..ctor(int)""
  IL_0034:  ldloc.3
  IL_0035:  constrained. ""T""
  IL_003b:  callvirt   ""void IMoveable.this[int].set""
  IL_0040:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_Value_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[1] ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[1] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       72 (0x48)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.1
  IL_0007:  ldloca.s   V_1
  IL_0009:  stloc.0
  IL_000a:  ldloc.0
  IL_000b:  ldc.i4.1
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int? IMoveable.this[int].get""
  IL_0017:  stloc.2
  IL_0018:  ldloca.s   V_2
  IL_001a:  call       ""int int?.GetValueOrDefault()""
  IL_001f:  stloc.3
  IL_0020:  ldloca.s   V_2
  IL_0022:  call       ""bool int?.HasValue.get""
  IL_0027:  brtrue.s   IL_0047
  IL_0029:  ldarg.0
  IL_002a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_002f:  stloc.3
  IL_0030:  ldloc.0
  IL_0031:  ldc.i4.1
  IL_0032:  ldloca.s   V_4
  IL_0034:  ldloc.3
  IL_0035:  call       ""int?..ctor(int)""
  IL_003a:  ldloc.s    V_4
  IL_003c:  constrained. ""T""
  IL_0042:  callvirt   ""void IMoveable.this[int].set""
  IL_0047:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       97 (0x61)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int? V_3,
                int V_4,
                T V_5,
                int? V_6)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_5
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_5
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldloc.0
  IL_0021:  ldc.i4.1
  IL_0022:  constrained. ""T""
  IL_0028:  callvirt   ""int? IMoveable.this[int].get""
  IL_002d:  stloc.3
  IL_002e:  ldloca.s   V_3
  IL_0030:  call       ""int int?.GetValueOrDefault()""
  IL_0035:  stloc.s    V_4
  IL_0037:  ldloca.s   V_3
  IL_0039:  call       ""bool int?.HasValue.get""
  IL_003e:  brtrue.s   IL_0060
  IL_0040:  ldarg.0
  IL_0041:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0046:  stloc.s    V_4
  IL_0048:  ldloc.0
  IL_0049:  ldc.i4.1
  IL_004a:  ldloca.s   V_6
  IL_004c:  ldloc.s    V_4
  IL_004e:  call       ""int?..ctor(int)""
  IL_0053:  ldloc.s    V_6
  IL_0055:  constrained. ""T""
  IL_005b:  callvirt   ""void IMoveable.this[int].set""
  IL_0060:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_Value_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[1] ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[1] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       63 (0x3f)
  .maxstack  4
  .locals init (T& V_0,
                int? V_1,
                int V_2,
                int? V_3)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  ldc.i4.1
  IL_0004:  constrained. ""T""
  IL_000a:  callvirt   ""int? IMoveable.this[int].get""
  IL_000f:  stloc.1
  IL_0010:  ldloca.s   V_1
  IL_0012:  call       ""int int?.GetValueOrDefault()""
  IL_0017:  stloc.2
  IL_0018:  ldloca.s   V_1
  IL_001a:  call       ""bool int?.HasValue.get""
  IL_001f:  brtrue.s   IL_003e
  IL_0021:  ldarg.0
  IL_0022:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0027:  stloc.2
  IL_0028:  ldloc.0
  IL_0029:  ldc.i4.1
  IL_002a:  ldloca.s   V_3
  IL_002c:  ldloc.2
  IL_002d:  call       ""int?..ctor(int)""
  IL_0032:  ldloc.3
  IL_0033:  constrained. ""T""
  IL_0039:  callvirt   ""void IMoveable.this[int].set""
  IL_003e:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_Value_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[1] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[1] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      241 (0xf1)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                int? V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0078
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_001c:  box        ""T""
    IL_0021:  ldc.i4.1
    IL_0022:  callvirt   ""int? IMoveable.this[int].get""
    IL_0027:  stloc.1
    IL_0028:  ldloca.s   V_1
    IL_002a:  call       ""int int?.GetValueOrDefault()""
    IL_002f:  stloc.2
    IL_0030:  ldloca.s   V_1
    IL_0032:  call       ""bool int?.HasValue.get""
    IL_0037:  brtrue.s   IL_00b6
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_003f:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0044:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0049:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_004e:  stloc.3
    IL_004f:  ldloca.s   V_3
    IL_0051:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0056:  brtrue.s   IL_0094
    IL_0058:  ldarg.0
    IL_0059:  ldc.i4.0
    IL_005a:  dup
    IL_005b:  stloc.0
    IL_005c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0061:  ldarg.0
    IL_0062:  ldloc.3
    IL_0063:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  ldarg.0
    IL_0069:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_006e:  ldloca.s   V_3
    IL_0070:  ldarg.0
    IL_0071:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0076:  leave.s    IL_00f0
    IL_0078:  ldarg.0
    IL_0079:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007e:  stloc.3
    IL_007f:  ldarg.0
    IL_0080:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0085:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_008b:  ldarg.0
    IL_008c:  ldc.i4.m1
    IL_008d:  dup
    IL_008e:  stloc.0
    IL_008f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0094:  ldloca.s   V_3
    IL_0096:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_009b:  stloc.2
    IL_009c:  ldarg.0
    IL_009d:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a2:  box        ""T""
    IL_00a7:  ldc.i4.1
    IL_00a8:  ldloc.2
    IL_00a9:  newobj     ""int?..ctor(int)""
    IL_00ae:  dup
    IL_00af:  stloc.s    V_4
    IL_00b1:  callvirt   ""void IMoveable.this[int].set""
    IL_00b6:  ldarg.0
    IL_00b7:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00bc:  initobj    ""T""
    IL_00c2:  leave.s    IL_00dd
  }
  catch System.Exception
  {
    IL_00c4:  stloc.s    V_5
    IL_00c6:  ldarg.0
    IL_00c7:  ldc.i4.s   -2
    IL_00c9:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ce:  ldarg.0
    IL_00cf:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00d4:  ldloc.s    V_5
    IL_00d6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00db:  leave.s    IL_00f0
  }
  IL_00dd:  ldarg.0
  IL_00de:  ldc.i4.s   -2
  IL_00e0:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00e5:  ldarg.0
  IL_00e6:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00eb:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00f0:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      319 (0x13f)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00ac
    IL_000d:  ldloca.s   V_3
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.3
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldloca.s   V_3
    IL_002b:  initobj    ""T""
    IL_0031:  ldloc.3
    IL_0032:  box        ""T""
    IL_0037:  brtrue.s   IL_0041
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_003f:  br.s       IL_0047
    IL_0041:  ldarg.0
    IL_0042:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0047:  ldc.i4.1
    IL_0048:  constrained. ""T""
    IL_004e:  callvirt   ""int? IMoveable.this[int].get""
    IL_0053:  stloc.1
    IL_0054:  ldloca.s   V_1
    IL_0056:  call       ""int int?.GetValueOrDefault()""
    IL_005b:  stloc.2
    IL_005c:  ldloca.s   V_1
    IL_005e:  call       ""bool int?.HasValue.get""
    IL_0063:  brtrue     IL_0104
    IL_0068:  ldarg.0
    IL_0069:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_006e:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0073:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0078:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_007d:  stloc.s    V_4
    IL_007f:  ldloca.s   V_4
    IL_0081:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0086:  brtrue.s   IL_00c9
    IL_0088:  ldarg.0
    IL_0089:  ldc.i4.0
    IL_008a:  dup
    IL_008b:  stloc.0
    IL_008c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0091:  ldarg.0
    IL_0092:  ldloc.s    V_4
    IL_0094:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0099:  ldarg.0
    IL_009a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_009f:  ldloca.s   V_4
    IL_00a1:  ldarg.0
    IL_00a2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00a7:  leave      IL_013e
    IL_00ac:  ldarg.0
    IL_00ad:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00b2:  stloc.s    V_4
    IL_00b4:  ldarg.0
    IL_00b5:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00ba:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00c0:  ldarg.0
    IL_00c1:  ldc.i4.m1
    IL_00c2:  dup
    IL_00c3:  stloc.0
    IL_00c4:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00c9:  ldloca.s   V_4
    IL_00cb:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00d0:  stloc.2
    IL_00d1:  ldloca.s   V_3
    IL_00d3:  initobj    ""T""
    IL_00d9:  ldloc.3
    IL_00da:  box        ""T""
    IL_00df:  brtrue.s   IL_00e9
    IL_00e1:  ldarg.0
    IL_00e2:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00e7:  br.s       IL_00ef
    IL_00e9:  ldarg.0
    IL_00ea:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00ef:  ldc.i4.1
    IL_00f0:  ldloc.2
    IL_00f1:  newobj     ""int?..ctor(int)""
    IL_00f6:  dup
    IL_00f7:  stloc.s    V_5
    IL_00f9:  constrained. ""T""
    IL_00ff:  callvirt   ""void IMoveable.this[int].set""
    IL_0104:  ldarg.0
    IL_0105:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_010a:  initobj    ""T""
    IL_0110:  leave.s    IL_012b
  }
  catch System.Exception
  {
    IL_0112:  stloc.s    V_6
    IL_0114:  ldarg.0
    IL_0115:  ldc.i4.s   -2
    IL_0117:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_011c:  ldarg.0
    IL_011d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0122:  ldloc.s    V_6
    IL_0124:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0129:  leave.s    IL_013e
  }
  IL_012b:  ldarg.0
  IL_012c:  ldc.i4.s   -2
  IL_012e:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0133:  ldarg.0
  IL_0134:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0139:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_013e:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_Value_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[1] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[1] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '-1'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      219 (0xdb)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                int? V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006d
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  ldc.i4.1
    IL_0011:  constrained. ""T""
    IL_0017:  callvirt   ""int? IMoveable.this[int].get""
    IL_001c:  stloc.1
    IL_001d:  ldloca.s   V_1
    IL_001f:  call       ""int int?.GetValueOrDefault()""
    IL_0024:  stloc.2
    IL_0025:  ldloca.s   V_1
    IL_0027:  call       ""bool int?.HasValue.get""
    IL_002c:  brtrue.s   IL_00ac
    IL_002e:  ldarg.0
    IL_002f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0034:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0039:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_003e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0043:  stloc.3
    IL_0044:  ldloca.s   V_3
    IL_0046:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_004b:  brtrue.s   IL_0089
    IL_004d:  ldarg.0
    IL_004e:  ldc.i4.0
    IL_004f:  dup
    IL_0050:  stloc.0
    IL_0051:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0056:  ldarg.0
    IL_0057:  ldloc.3
    IL_0058:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005d:  ldarg.0
    IL_005e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0063:  ldloca.s   V_3
    IL_0065:  ldarg.0
    IL_0066:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_006b:  leave.s    IL_00da
    IL_006d:  ldarg.0
    IL_006e:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0073:  stloc.3
    IL_0074:  ldarg.0
    IL_0075:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007a:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0080:  ldarg.0
    IL_0081:  ldc.i4.m1
    IL_0082:  dup
    IL_0083:  stloc.0
    IL_0084:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0089:  ldloca.s   V_3
    IL_008b:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0090:  stloc.2
    IL_0091:  ldarg.0
    IL_0092:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0097:  ldc.i4.1
    IL_0098:  ldloc.2
    IL_0099:  newobj     ""int?..ctor(int)""
    IL_009e:  dup
    IL_009f:  stloc.s    V_4
    IL_00a1:  constrained. ""T""
    IL_00a7:  callvirt   ""void IMoveable.this[int].set""
    IL_00ac:  leave.s    IL_00c7
  }
  catch System.Exception
  {
    IL_00ae:  stloc.s    V_5
    IL_00b0:  ldarg.0
    IL_00b1:  ldc.i4.s   -2
    IL_00b3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b8:  ldarg.0
    IL_00b9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00be:  ldloc.s    V_5
    IL_00c0:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00c5:  leave.s    IL_00da
  }
  IL_00c7:  ldarg.0
  IL_00c8:  ldc.i4.s   -2
  IL_00ca:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00cf:  ldarg.0
  IL_00d0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00d5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00da:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_IndexAndValue()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
   // Code size       79 (0x4f)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_1
  IL_0004:  stloc.0
  IL_0005:  ldarga.s   V_0
  IL_0007:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000c:  stloc.2
  IL_000d:  ldloc.0
  IL_000e:  ldloc.2
  IL_000f:  constrained. ""T""
  IL_0015:  callvirt   ""int? IMoveable.this[int].get""
  IL_001a:  stloc.3
  IL_001b:  ldloca.s   V_3
  IL_001d:  call       ""int int?.GetValueOrDefault()""
  IL_0022:  stloc.s    V_4
  IL_0024:  ldloca.s   V_3
  IL_0026:  call       ""bool int?.HasValue.get""
  IL_002b:  brtrue.s   IL_004e
  IL_002d:  ldarga.s   V_0
  IL_002f:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0034:  stloc.s    V_4
  IL_0036:  ldloc.0
  IL_0037:  ldloc.2
  IL_0038:  ldloca.s   V_5
  IL_003a:  ldloc.s    V_4
  IL_003c:  call       ""int?..ctor(int)""
  IL_0041:  ldloc.s    V_5
  IL_0043:  constrained. ""T""
  IL_0049:  callvirt   ""void IMoveable.this[int].set""
  IL_004e:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      108 (0x6c)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int? V_4,
                int V_5,
                T V_6,
                int? V_7)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_6
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_6
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  ldloc.3
  IL_002b:  constrained. ""T""
  IL_0031:  callvirt   ""int? IMoveable.this[int].get""
  IL_0036:  stloc.s    V_4
  IL_0038:  ldloca.s   V_4
  IL_003a:  call       ""int int?.GetValueOrDefault()""
  IL_003f:  stloc.s    V_5
  IL_0041:  ldloca.s   V_4
  IL_0043:  call       ""bool int?.HasValue.get""
  IL_0048:  brtrue.s   IL_006b
  IL_004a:  ldarga.s   V_0
  IL_004c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0051:  stloc.s    V_5
  IL_0053:  ldloc.0
  IL_0054:  ldloc.3
  IL_0055:  ldloca.s   V_7
  IL_0057:  ldloc.s    V_5
  IL_0059:  call       ""int?..ctor(int)""
  IL_005e:  ldloc.s    V_7
  IL_0060:  constrained. ""T""
  IL_0066:  callvirt   ""void IMoveable.this[int].set""
  IL_006b:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_IndexAndValue()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       74 (0x4a)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  ldloc.1
  IL_000d:  constrained. ""T""
  IL_0013:  callvirt   ""int? IMoveable.this[int].get""
  IL_0018:  stloc.2
  IL_0019:  ldloca.s   V_2
  IL_001b:  call       ""int int?.GetValueOrDefault()""
  IL_0020:  stloc.3
  IL_0021:  ldloca.s   V_2
  IL_0023:  call       ""bool int?.HasValue.get""
  IL_0028:  brtrue.s   IL_0049
  IL_002a:  ldarga.s   V_0
  IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0031:  stloc.3
  IL_0032:  ldloc.0
  IL_0033:  ldloc.1
  IL_0034:  ldloca.s   V_4
  IL_0036:  ldloc.3
  IL_0037:  call       ""int?..ctor(int)""
  IL_003c:  ldloc.s    V_4
  IL_003e:  constrained. ""T""
  IL_0044:  callvirt   ""void IMoveable.this[int].set""
  IL_0049:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_IndexAndValue_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       82 (0x52)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.1
  IL_0007:  ldloca.s   V_1
  IL_0009:  stloc.0
  IL_000a:  ldarg.0
  IL_000b:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0010:  stloc.2
  IL_0011:  ldloc.0
  IL_0012:  ldloc.2
  IL_0013:  constrained. ""T""
  IL_0019:  callvirt   ""int? IMoveable.this[int].get""
  IL_001e:  stloc.3
  IL_001f:  ldloca.s   V_3
  IL_0021:  call       ""int int?.GetValueOrDefault()""
  IL_0026:  stloc.s    V_4
  IL_0028:  ldloca.s   V_3
  IL_002a:  call       ""bool int?.HasValue.get""
  IL_002f:  brtrue.s   IL_0051
  IL_0031:  ldarg.0
  IL_0032:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0037:  stloc.s    V_4
  IL_0039:  ldloc.0
  IL_003a:  ldloc.2
  IL_003b:  ldloca.s   V_5
  IL_003d:  ldloc.s    V_4
  IL_003f:  call       ""int?..ctor(int)""
  IL_0044:  ldloc.s    V_5
  IL_0046:  constrained. ""T""
  IL_004c:  callvirt   ""void IMoveable.this[int].set""
  IL_0051:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      105 (0x69)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int? V_4,
                int V_5,
                T V_6,
                int? V_7)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_6
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_6
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  ldloc.3
  IL_0029:  constrained. ""T""
  IL_002f:  callvirt   ""int? IMoveable.this[int].get""
  IL_0034:  stloc.s    V_4
  IL_0036:  ldloca.s   V_4
  IL_0038:  call       ""int int?.GetValueOrDefault()""
  IL_003d:  stloc.s    V_5
  IL_003f:  ldloca.s   V_4
  IL_0041:  call       ""bool int?.HasValue.get""
  IL_0046:  brtrue.s   IL_0068
  IL_0048:  ldarg.0
  IL_0049:  call       ""int Program.GetOffset<T>(ref T)""
  IL_004e:  stloc.s    V_5
  IL_0050:  ldloc.0
  IL_0051:  ldloc.3
  IL_0052:  ldloca.s   V_7
  IL_0054:  ldloc.s    V_5
  IL_0056:  call       ""int?..ctor(int)""
  IL_005b:  ldloc.s    V_7
  IL_005d:  constrained. ""T""
  IL_0063:  callvirt   ""void IMoveable.this[int].set""
  IL_0068:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_IndexAndValue_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       71 (0x47)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  ldloc.1
  IL_000b:  constrained. ""T""
  IL_0011:  callvirt   ""int? IMoveable.this[int].get""
  IL_0016:  stloc.2
  IL_0017:  ldloca.s   V_2
  IL_0019:  call       ""int int?.GetValueOrDefault()""
  IL_001e:  stloc.3
  IL_001f:  ldloca.s   V_2
  IL_0021:  call       ""bool int?.HasValue.get""
  IL_0026:  brtrue.s   IL_0046
  IL_0028:  ldarg.0
  IL_0029:  call       ""int Program.GetOffset<T>(ref T)""
  IL_002e:  stloc.3
  IL_002f:  ldloc.0
  IL_0030:  ldloc.1
  IL_0031:  ldloca.s   V_4
  IL_0033:  ldloc.3
  IL_0034:  call       ""int?..ctor(int)""
  IL_0039:  ldloc.s    V_4
  IL_003b:  constrained. ""T""
  IL_0041:  callvirt   ""void IMoveable.this[int].set""
  IL_0046:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_IndexAndValue_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[GetOffset(ref item)] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      274 (0x112)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                int? V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_0094
    IL_000d:  ldarg.0
    IL_000e:  ldarg.0
    IL_000f:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0014:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0019:  ldarg.0
    IL_001a:  ldarg.0
    IL_001b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0020:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0025:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_002a:  ldarg.0
    IL_002b:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0030:  box        ""T""
    IL_0035:  ldarg.0
    IL_0036:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_003b:  callvirt   ""int? IMoveable.this[int].get""
    IL_0040:  stloc.1
    IL_0041:  ldloca.s   V_1
    IL_0043:  call       ""int int?.GetValueOrDefault()""
    IL_0048:  stloc.2
    IL_0049:  ldloca.s   V_1
    IL_004b:  call       ""bool int?.HasValue.get""
    IL_0050:  brtrue     IL_00d7
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_005b:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0060:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0065:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_006a:  stloc.3
    IL_006b:  ldloca.s   V_3
    IL_006d:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0072:  brtrue.s   IL_00b0
    IL_0074:  ldarg.0
    IL_0075:  ldc.i4.0
    IL_0076:  dup
    IL_0077:  stloc.0
    IL_0078:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007d:  ldarg.0
    IL_007e:  ldloc.3
    IL_007f:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0084:  ldarg.0
    IL_0085:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_008a:  ldloca.s   V_3
    IL_008c:  ldarg.0
    IL_008d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0092:  leave.s    IL_0111
    IL_0094:  ldarg.0
    IL_0095:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_009a:  stloc.3
    IL_009b:  ldarg.0
    IL_009c:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00a1:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00a7:  ldarg.0
    IL_00a8:  ldc.i4.m1
    IL_00a9:  dup
    IL_00aa:  stloc.0
    IL_00ab:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b0:  ldloca.s   V_3
    IL_00b2:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00b7:  stloc.2
    IL_00b8:  ldarg.0
    IL_00b9:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00be:  box        ""T""
    IL_00c3:  ldarg.0
    IL_00c4:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00c9:  ldloc.2
    IL_00ca:  newobj     ""int?..ctor(int)""
    IL_00cf:  dup
    IL_00d0:  stloc.s    V_4
    IL_00d2:  callvirt   ""void IMoveable.this[int].set""
    IL_00d7:  ldarg.0
    IL_00d8:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00dd:  initobj    ""T""
    IL_00e3:  leave.s    IL_00fe
  }
  catch System.Exception
  {
    IL_00e5:  stloc.s    V_5
    IL_00e7:  ldarg.0
    IL_00e8:  ldc.i4.s   -2
    IL_00ea:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ef:  ldarg.0
    IL_00f0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00f5:  ldloc.s    V_5
    IL_00f7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00fc:  leave.s    IL_0111
  }
  IL_00fe:  ldarg.0
  IL_00ff:  ldc.i4.s   -2
  IL_0101:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0106:  ldarg.0
  IL_0107:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_010c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0111:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      346 (0x15a)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00c2
    IL_000d:  ldloca.s   V_3
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.3
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldarg.0
    IL_002a:  ldarg.0
    IL_002b:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0030:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0035:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_003a:  ldloca.s   V_3
    IL_003c:  initobj    ""T""
    IL_0042:  ldloc.3
    IL_0043:  box        ""T""
    IL_0048:  brtrue.s   IL_0052
    IL_004a:  ldarg.0
    IL_004b:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0050:  br.s       IL_0058
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0058:  ldarg.0
    IL_0059:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_005e:  constrained. ""T""
    IL_0064:  callvirt   ""int? IMoveable.this[int].get""
    IL_0069:  stloc.1
    IL_006a:  ldloca.s   V_1
    IL_006c:  call       ""int int?.GetValueOrDefault()""
    IL_0071:  stloc.2
    IL_0072:  ldloca.s   V_1
    IL_0074:  call       ""bool int?.HasValue.get""
    IL_0079:  brtrue     IL_011f
    IL_007e:  ldarg.0
    IL_007f:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0084:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0089:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_008e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0093:  stloc.s    V_4
    IL_0095:  ldloca.s   V_4
    IL_0097:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_009c:  brtrue.s   IL_00df
    IL_009e:  ldarg.0
    IL_009f:  ldc.i4.0
    IL_00a0:  dup
    IL_00a1:  stloc.0
    IL_00a2:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00a7:  ldarg.0
    IL_00a8:  ldloc.s    V_4
    IL_00aa:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00af:  ldarg.0
    IL_00b0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00b5:  ldloca.s   V_4
    IL_00b7:  ldarg.0
    IL_00b8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00bd:  leave      IL_0159
    IL_00c2:  ldarg.0
    IL_00c3:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00c8:  stloc.s    V_4
    IL_00ca:  ldarg.0
    IL_00cb:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00d0:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00d6:  ldarg.0
    IL_00d7:  ldc.i4.m1
    IL_00d8:  dup
    IL_00d9:  stloc.0
    IL_00da:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00df:  ldloca.s   V_4
    IL_00e1:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00e6:  stloc.2
    IL_00e7:  ldloca.s   V_3
    IL_00e9:  initobj    ""T""
    IL_00ef:  ldloc.3
    IL_00f0:  box        ""T""
    IL_00f5:  brtrue.s   IL_00ff
    IL_00f7:  ldarg.0
    IL_00f8:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00fd:  br.s       IL_0105
    IL_00ff:  ldarg.0
    IL_0100:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0105:  ldarg.0
    IL_0106:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_010b:  ldloc.2
    IL_010c:  newobj     ""int?..ctor(int)""
    IL_0111:  dup
    IL_0112:  stloc.s    V_5
    IL_0114:  constrained. ""T""
    IL_011a:  callvirt   ""void IMoveable.this[int].set""
    IL_011f:  ldarg.0
    IL_0120:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0125:  initobj    ""T""
    IL_012b:  leave.s    IL_0146
  }
  catch System.Exception
  {
    IL_012d:  stloc.s    V_6
    IL_012f:  ldarg.0
    IL_0130:  ldc.i4.s   -2
    IL_0132:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0137:  ldarg.0
    IL_0138:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_013d:  ldloc.s    V_6
    IL_013f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0144:  leave.s    IL_0159
  }
  IL_0146:  ldarg.0
  IL_0147:  ldc.i4.s   -2
  IL_0149:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_014e:  ldarg.0
  IL_014f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0154:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0159:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_IndexAndValue_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[GetOffset(ref item)] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[GetOffset(ref item)] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      249 (0xf9)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                int? V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0086
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0016:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_001b:  ldarg.0
    IL_001c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0021:  ldarg.0
    IL_0022:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0027:  constrained. ""T""
    IL_002d:  callvirt   ""int? IMoveable.this[int].get""
    IL_0032:  stloc.1
    IL_0033:  ldloca.s   V_1
    IL_0035:  call       ""int int?.GetValueOrDefault()""
    IL_003a:  stloc.2
    IL_003b:  ldloca.s   V_1
    IL_003d:  call       ""bool int?.HasValue.get""
    IL_0042:  brtrue     IL_00ca
    IL_0047:  ldarg.0
    IL_0048:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_004d:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0052:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0057:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_005c:  stloc.3
    IL_005d:  ldloca.s   V_3
    IL_005f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0064:  brtrue.s   IL_00a2
    IL_0066:  ldarg.0
    IL_0067:  ldc.i4.0
    IL_0068:  dup
    IL_0069:  stloc.0
    IL_006a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_006f:  ldarg.0
    IL_0070:  ldloc.3
    IL_0071:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0076:  ldarg.0
    IL_0077:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_007c:  ldloca.s   V_3
    IL_007e:  ldarg.0
    IL_007f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0084:  leave.s    IL_00f8
    IL_0086:  ldarg.0
    IL_0087:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_008c:  stloc.3
    IL_008d:  ldarg.0
    IL_008e:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0093:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0099:  ldarg.0
    IL_009a:  ldc.i4.m1
    IL_009b:  dup
    IL_009c:  stloc.0
    IL_009d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00a2:  ldloca.s   V_3
    IL_00a4:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00a9:  stloc.2
    IL_00aa:  ldarg.0
    IL_00ab:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b0:  ldarg.0
    IL_00b1:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b6:  ldloc.2
    IL_00b7:  newobj     ""int?..ctor(int)""
    IL_00bc:  dup
    IL_00bd:  stloc.s    V_4
    IL_00bf:  constrained. ""T""
    IL_00c5:  callvirt   ""void IMoveable.this[int].set""
    IL_00ca:  leave.s    IL_00e5
  }
  catch System.Exception
  {
    IL_00cc:  stloc.s    V_5
    IL_00ce:  ldarg.0
    IL_00cf:  ldc.i4.s   -2
    IL_00d1:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00d6:  ldarg.0
    IL_00d7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00dc:  ldloc.s    V_5
    IL_00de:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00e3:  leave.s    IL_00f8
  }
  IL_00e5:  ldarg.0
  IL_00e6:  ldc.i4.s   -2
  IL_00e8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00ed:  ldarg.0
  IL_00ee:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00f3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00f8:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_IndexAndValue_Async_03()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= GetOffset(ref item);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
      // Code size      259 (0x103)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_005a
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.s    V_4
    IL_002d:  ldloca.s   V_4
    IL_002f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0034:  brtrue.s   IL_0077
    IL_0036:  ldarg.0
    IL_0037:  ldc.i4.0
    IL_0038:  dup
    IL_0039:  stloc.0
    IL_003a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003f:  ldarg.0
    IL_0040:  ldloc.s    V_4
    IL_0042:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0047:  ldarg.0
    IL_0048:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004d:  ldloca.s   V_4
    IL_004f:  ldarg.0
    IL_0050:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0055:  leave      IL_0102
    IL_005a:  ldarg.0
    IL_005b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0060:  stloc.s    V_4
    IL_0062:  ldarg.0
    IL_0063:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006e:  ldarg.0
    IL_006f:  ldc.i4.m1
    IL_0070:  dup
    IL_0071:  stloc.0
    IL_0072:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0077:  ldloca.s   V_4
    IL_0079:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007e:  stloc.1
    IL_007f:  ldarg.0
    IL_0080:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0085:  box        ""T""
    IL_008a:  ldloc.1
    IL_008b:  callvirt   ""int? IMoveable.this[int].get""
    IL_0090:  stloc.2
    IL_0091:  ldloca.s   V_2
    IL_0093:  call       ""int int?.GetValueOrDefault()""
    IL_0098:  stloc.3
    IL_0099:  ldloca.s   V_2
    IL_009b:  call       ""bool int?.HasValue.get""
    IL_00a0:  brtrue.s   IL_00c8
    IL_00a2:  ldarg.0
    IL_00a3:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00a8:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00ad:  stloc.3
    IL_00ae:  ldarg.0
    IL_00af:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b4:  box        ""T""
    IL_00b9:  ldloc.1
    IL_00ba:  ldloc.3
    IL_00bb:  newobj     ""int?..ctor(int)""
    IL_00c0:  dup
    IL_00c1:  stloc.s    V_5
    IL_00c3:  callvirt   ""void IMoveable.this[int].set""
    IL_00c8:  ldarg.0
    IL_00c9:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00ce:  initobj    ""T""
    IL_00d4:  leave.s    IL_00ef
  }
  catch System.Exception
  {
    IL_00d6:  stloc.s    V_6
    IL_00d8:  ldarg.0
    IL_00d9:  ldc.i4.s   -2
    IL_00db:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e0:  ldarg.0
    IL_00e1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e6:  ldloc.s    V_6
    IL_00e8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ed:  leave.s    IL_0102
  }
  IL_00ef:  ldarg.0
  IL_00f0:  ldc.i4.s   -2
  IL_00f2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00f7:  ldarg.0
  IL_00f8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00fd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0102:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      328 (0x148)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006b
    IL_000a:  ldloca.s   V_4
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.s    V_4
    IL_0014:  box        ""T""
    IL_0019:  brtrue.s   IL_0027
    IL_001b:  ldarg.0
    IL_001c:  ldarg.0
    IL_001d:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0022:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0027:  ldarg.0
    IL_0028:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002d:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0032:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0037:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003c:  stloc.s    V_5
    IL_003e:  ldloca.s   V_5
    IL_0040:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0045:  brtrue.s   IL_0088
    IL_0047:  ldarg.0
    IL_0048:  ldc.i4.0
    IL_0049:  dup
    IL_004a:  stloc.0
    IL_004b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0050:  ldarg.0
    IL_0051:  ldloc.s    V_5
    IL_0053:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  ldarg.0
    IL_0059:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005e:  ldloca.s   V_5
    IL_0060:  ldarg.0
    IL_0061:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0066:  leave      IL_0147
    IL_006b:  ldarg.0
    IL_006c:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0071:  stloc.s    V_5
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0079:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007f:  ldarg.0
    IL_0080:  ldc.i4.m1
    IL_0081:  dup
    IL_0082:  stloc.0
    IL_0083:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0088:  ldloca.s   V_5
    IL_008a:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008f:  stloc.1
    IL_0090:  ldloca.s   V_4
    IL_0092:  initobj    ""T""
    IL_0098:  ldloc.s    V_4
    IL_009a:  box        ""T""
    IL_009f:  brtrue.s   IL_00a9
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a7:  br.s       IL_00af
    IL_00a9:  ldarg.0
    IL_00aa:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00af:  ldloc.1
    IL_00b0:  constrained. ""T""
    IL_00b6:  callvirt   ""int? IMoveable.this[int].get""
    IL_00bb:  stloc.2
    IL_00bc:  ldloca.s   V_2
    IL_00be:  call       ""int int?.GetValueOrDefault()""
    IL_00c3:  stloc.3
    IL_00c4:  ldloca.s   V_2
    IL_00c6:  call       ""bool int?.HasValue.get""
    IL_00cb:  brtrue.s   IL_010d
    IL_00cd:  ldarg.0
    IL_00ce:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00d3:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00d8:  stloc.3
    IL_00d9:  ldloca.s   V_4
    IL_00db:  initobj    ""T""
    IL_00e1:  ldloc.s    V_4
    IL_00e3:  box        ""T""
    IL_00e8:  brtrue.s   IL_00f2
    IL_00ea:  ldarg.0
    IL_00eb:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f0:  br.s       IL_00f8
    IL_00f2:  ldarg.0
    IL_00f3:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00f8:  ldloc.1
    IL_00f9:  ldloc.3
    IL_00fa:  newobj     ""int?..ctor(int)""
    IL_00ff:  dup
    IL_0100:  stloc.s    V_6
    IL_0102:  constrained. ""T""
    IL_0108:  callvirt   ""void IMoveable.this[int].set""
    IL_010d:  ldarg.0
    IL_010e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0113:  initobj    ""T""
    IL_0119:  leave.s    IL_0134
  }
  catch System.Exception
  {
    IL_011b:  stloc.s    V_7
    IL_011d:  ldarg.0
    IL_011e:  ldc.i4.s   -2
    IL_0120:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0125:  ldarg.0
    IL_0126:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_012b:  ldloc.s    V_7
    IL_012d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0132:  leave.s    IL_0147
  }
  IL_0134:  ldarg.0
  IL_0135:  ldc.i4.s   -2
  IL_0137:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_013c:  ldarg.0
  IL_013d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0142:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0147:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_IndexAndValue_Async_03()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= GetOffset(ref item);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      237 (0xed)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004e
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.s    V_4
    IL_0021:  ldloca.s   V_4
    IL_0023:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0028:  brtrue.s   IL_006b
    IL_002a:  ldarg.0
    IL_002b:  ldc.i4.0
    IL_002c:  dup
    IL_002d:  stloc.0
    IL_002e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0033:  ldarg.0
    IL_0034:  ldloc.s    V_4
    IL_0036:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_003b:  ldarg.0
    IL_003c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0041:  ldloca.s   V_4
    IL_0043:  ldarg.0
    IL_0044:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0049:  leave      IL_00ec
    IL_004e:  ldarg.0
    IL_004f:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0054:  stloc.s    V_4
    IL_0056:  ldarg.0
    IL_0057:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0062:  ldarg.0
    IL_0063:  ldc.i4.m1
    IL_0064:  dup
    IL_0065:  stloc.0
    IL_0066:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_006b:  ldloca.s   V_4
    IL_006d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0072:  stloc.1
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0079:  ldloc.1
    IL_007a:  constrained. ""T""
    IL_0080:  callvirt   ""int? IMoveable.this[int].get""
    IL_0085:  stloc.2
    IL_0086:  ldloca.s   V_2
    IL_0088:  call       ""int int?.GetValueOrDefault()""
    IL_008d:  stloc.3
    IL_008e:  ldloca.s   V_2
    IL_0090:  call       ""bool int?.HasValue.get""
    IL_0095:  brtrue.s   IL_00be
    IL_0097:  ldarg.0
    IL_0098:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_009d:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00a2:  stloc.3
    IL_00a3:  ldarg.0
    IL_00a4:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00a9:  ldloc.1
    IL_00aa:  ldloc.3
    IL_00ab:  newobj     ""int?..ctor(int)""
    IL_00b0:  dup
    IL_00b1:  stloc.s    V_5
    IL_00b3:  constrained. ""T""
    IL_00b9:  callvirt   ""void IMoveable.this[int].set""
    IL_00be:  leave.s    IL_00d9
  }
  catch System.Exception
  {
    IL_00c0:  stloc.s    V_6
    IL_00c2:  ldarg.0
    IL_00c3:  ldc.i4.s   -2
    IL_00c5:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ca:  ldarg.0
    IL_00cb:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00d0:  ldloc.s    V_6
    IL_00d2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d7:  leave.s    IL_00ec
  }
  IL_00d9:  ldarg.0
  IL_00da:  ldc.i4.s   -2
  IL_00dc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00e1:  ldarg.0
  IL_00e2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00e7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ec:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Class_IndexAndValue_Async_04()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '1'
Position set for item '1'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
   // Code size      376 (0x178)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0061
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00f9
    IL_0011:  ldarg.0
    IL_0012:  ldarg.0
    IL_0013:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0018:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_001d:  ldarg.0
    IL_001e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0028:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_002d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0032:  stloc.s    V_4
    IL_0034:  ldloca.s   V_4
    IL_0036:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003b:  brtrue.s   IL_007e
    IL_003d:  ldarg.0
    IL_003e:  ldc.i4.0
    IL_003f:  dup
    IL_0040:  stloc.0
    IL_0041:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0046:  ldarg.0
    IL_0047:  ldloc.s    V_4
    IL_0049:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004e:  ldarg.0
    IL_004f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0054:  ldloca.s   V_4
    IL_0056:  ldarg.0
    IL_0057:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_005c:  leave      IL_0177
    IL_0061:  ldarg.0
    IL_0062:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0067:  stloc.s    V_4
    IL_0069:  ldarg.0
    IL_006a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0075:  ldarg.0
    IL_0076:  ldc.i4.m1
    IL_0077:  dup
    IL_0078:  stloc.0
    IL_0079:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007e:  ldloca.s   V_4
    IL_0080:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0085:  stloc.1
    IL_0086:  ldarg.0
    IL_0087:  ldloc.1
    IL_0088:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_008d:  ldarg.0
    IL_008e:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0093:  box        ""T""
    IL_0098:  ldarg.0
    IL_0099:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_009e:  callvirt   ""int? IMoveable.this[int].get""
    IL_00a3:  stloc.2
    IL_00a4:  ldloca.s   V_2
    IL_00a6:  call       ""int int?.GetValueOrDefault()""
    IL_00ab:  stloc.3
    IL_00ac:  ldloca.s   V_2
    IL_00ae:  call       ""bool int?.HasValue.get""
    IL_00b3:  brtrue     IL_013d
    IL_00b8:  ldarg.0
    IL_00b9:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00be:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00c3:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00c8:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00cd:  stloc.s    V_4
    IL_00cf:  ldloca.s   V_4
    IL_00d1:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00d6:  brtrue.s   IL_0116
    IL_00d8:  ldarg.0
    IL_00d9:  ldc.i4.1
    IL_00da:  dup
    IL_00db:  stloc.0
    IL_00dc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e1:  ldarg.0
    IL_00e2:  ldloc.s    V_4
    IL_00e4:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00e9:  ldarg.0
    IL_00ea:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00ef:  ldloca.s   V_4
    IL_00f1:  ldarg.0
    IL_00f2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00f7:  leave.s    IL_0177
    IL_00f9:  ldarg.0
    IL_00fa:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00ff:  stloc.s    V_4
    IL_0101:  ldarg.0
    IL_0102:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0107:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_010d:  ldarg.0
    IL_010e:  ldc.i4.m1
    IL_010f:  dup
    IL_0110:  stloc.0
    IL_0111:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0116:  ldloca.s   V_4
    IL_0118:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_011d:  stloc.3
    IL_011e:  ldarg.0
    IL_011f:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0124:  box        ""T""
    IL_0129:  ldarg.0
    IL_012a:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_012f:  ldloc.3
    IL_0130:  newobj     ""int?..ctor(int)""
    IL_0135:  dup
    IL_0136:  stloc.s    V_5
    IL_0138:  callvirt   ""void IMoveable.this[int].set""
    IL_013d:  ldarg.0
    IL_013e:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0143:  initobj    ""T""
    IL_0149:  leave.s    IL_0164
  }
  catch System.Exception
  {
    IL_014b:  stloc.s    V_6
    IL_014d:  ldarg.0
    IL_014e:  ldc.i4.s   -2
    IL_0150:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0155:  ldarg.0
    IL_0156:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_015b:  ldloc.s    V_6
    IL_015d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0162:  leave.s    IL_0177
  }
  IL_0164:  ldarg.0
  IL_0165:  ldc.i4.s   -2
  IL_0167:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_016c:  ldarg.0
  IL_016d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0172:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0177:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      448 (0x1c0)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0072
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_0127
    IL_0011:  ldloca.s   V_4
    IL_0013:  initobj    ""T""
    IL_0019:  ldloc.s    V_4
    IL_001b:  box        ""T""
    IL_0020:  brtrue.s   IL_002e
    IL_0022:  ldarg.0
    IL_0023:  ldarg.0
    IL_0024:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0029:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_002e:  ldarg.0
    IL_002f:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0034:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0039:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_003e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0043:  stloc.s    V_5
    IL_0045:  ldloca.s   V_5
    IL_0047:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_004c:  brtrue.s   IL_008f
    IL_004e:  ldarg.0
    IL_004f:  ldc.i4.0
    IL_0050:  dup
    IL_0051:  stloc.0
    IL_0052:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0057:  ldarg.0
    IL_0058:  ldloc.s    V_5
    IL_005a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0065:  ldloca.s   V_5
    IL_0067:  ldarg.0
    IL_0068:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_006d:  leave      IL_01bf
    IL_0072:  ldarg.0
    IL_0073:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0078:  stloc.s    V_5
    IL_007a:  ldarg.0
    IL_007b:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0080:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0086:  ldarg.0
    IL_0087:  ldc.i4.m1
    IL_0088:  dup
    IL_0089:  stloc.0
    IL_008a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_008f:  ldloca.s   V_5
    IL_0091:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0096:  stloc.1
    IL_0097:  ldarg.0
    IL_0098:  ldloc.1
    IL_0099:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_009e:  ldloca.s   V_4
    IL_00a0:  initobj    ""T""
    IL_00a6:  ldloc.s    V_4
    IL_00a8:  box        ""T""
    IL_00ad:  brtrue.s   IL_00b7
    IL_00af:  ldarg.0
    IL_00b0:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00b5:  br.s       IL_00bd
    IL_00b7:  ldarg.0
    IL_00b8:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00bd:  ldarg.0
    IL_00be:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00c3:  constrained. ""T""
    IL_00c9:  callvirt   ""int? IMoveable.this[int].get""
    IL_00ce:  stloc.2
    IL_00cf:  ldloca.s   V_2
    IL_00d1:  call       ""int int?.GetValueOrDefault()""
    IL_00d6:  stloc.3
    IL_00d7:  ldloca.s   V_2
    IL_00d9:  call       ""bool int?.HasValue.get""
    IL_00de:  brtrue     IL_0185
    IL_00e3:  ldarg.0
    IL_00e4:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00e9:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00ee:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00f3:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00f8:  stloc.s    V_5
    IL_00fa:  ldloca.s   V_5
    IL_00fc:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0101:  brtrue.s   IL_0144
    IL_0103:  ldarg.0
    IL_0104:  ldc.i4.1
    IL_0105:  dup
    IL_0106:  stloc.0
    IL_0107:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_010c:  ldarg.0
    IL_010d:  ldloc.s    V_5
    IL_010f:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0114:  ldarg.0
    IL_0115:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_011a:  ldloca.s   V_5
    IL_011c:  ldarg.0
    IL_011d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0122:  leave      IL_01bf
    IL_0127:  ldarg.0
    IL_0128:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_012d:  stloc.s    V_5
    IL_012f:  ldarg.0
    IL_0130:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0135:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_013b:  ldarg.0
    IL_013c:  ldc.i4.m1
    IL_013d:  dup
    IL_013e:  stloc.0
    IL_013f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0144:  ldloca.s   V_5
    IL_0146:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_014b:  stloc.3
    IL_014c:  ldloca.s   V_4
    IL_014e:  initobj    ""T""
    IL_0154:  ldloc.s    V_4
    IL_0156:  box        ""T""
    IL_015b:  brtrue.s   IL_0165
    IL_015d:  ldarg.0
    IL_015e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0163:  br.s       IL_016b
    IL_0165:  ldarg.0
    IL_0166:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_016b:  ldarg.0
    IL_016c:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0171:  ldloc.3
    IL_0172:  newobj     ""int?..ctor(int)""
    IL_0177:  dup
    IL_0178:  stloc.s    V_6
    IL_017a:  constrained. ""T""
    IL_0180:  callvirt   ""void IMoveable.this[int].set""
    IL_0185:  ldarg.0
    IL_0186:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_018b:  initobj    ""T""
    IL_0191:  leave.s    IL_01ac
  }
  catch System.Exception
  {
    IL_0193:  stloc.s    V_7
    IL_0195:  ldarg.0
    IL_0196:  ldc.i4.s   -2
    IL_0198:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_019d:  ldarg.0
    IL_019e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_01a3:  ldloc.s    V_7
    IL_01a5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_01aa:  leave.s    IL_01bf
  }
  IL_01ac:  ldarg.0
  IL_01ad:  ldc.i4.s   -2
  IL_01af:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_01b4:  ldarg.0
  IL_01b5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_01ba:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_01bf:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_Indexer_Struct_IndexAndValue_Async_04()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[await GetOffsetAsync(GetOffset(ref item))] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position get for item '-1'
Position set for item '-2'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      354 (0x162)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0055
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00ee
    IL_0011:  ldarg.0
    IL_0012:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0017:  call       ""int Program.GetOffset<T>(ref T)""
    IL_001c:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0021:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0026:  stloc.s    V_4
    IL_0028:  ldloca.s   V_4
    IL_002a:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_002f:  brtrue.s   IL_0072
    IL_0031:  ldarg.0
    IL_0032:  ldc.i4.0
    IL_0033:  dup
    IL_0034:  stloc.0
    IL_0035:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003a:  ldarg.0
    IL_003b:  ldloc.s    V_4
    IL_003d:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0042:  ldarg.0
    IL_0043:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0048:  ldloca.s   V_4
    IL_004a:  ldarg.0
    IL_004b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0050:  leave      IL_0161
    IL_0055:  ldarg.0
    IL_0056:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005b:  stloc.s    V_4
    IL_005d:  ldarg.0
    IL_005e:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0063:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0069:  ldarg.0
    IL_006a:  ldc.i4.m1
    IL_006b:  dup
    IL_006c:  stloc.0
    IL_006d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0072:  ldloca.s   V_4
    IL_0074:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0079:  stloc.1
    IL_007a:  ldarg.0
    IL_007b:  ldloc.1
    IL_007c:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0081:  ldarg.0
    IL_0082:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0087:  ldarg.0
    IL_0088:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008d:  constrained. ""T""
    IL_0093:  callvirt   ""int? IMoveable.this[int].get""
    IL_0098:  stloc.2
    IL_0099:  ldloca.s   V_2
    IL_009b:  call       ""int int?.GetValueOrDefault()""
    IL_00a0:  stloc.3
    IL_00a1:  ldloca.s   V_2
    IL_00a3:  call       ""bool int?.HasValue.get""
    IL_00a8:  brtrue     IL_0133
    IL_00ad:  ldarg.0
    IL_00ae:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b3:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00b8:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00bd:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00c2:  stloc.s    V_4
    IL_00c4:  ldloca.s   V_4
    IL_00c6:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00cb:  brtrue.s   IL_010b
    IL_00cd:  ldarg.0
    IL_00ce:  ldc.i4.1
    IL_00cf:  dup
    IL_00d0:  stloc.0
    IL_00d1:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00d6:  ldarg.0
    IL_00d7:  ldloc.s    V_4
    IL_00d9:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00de:  ldarg.0
    IL_00df:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e4:  ldloca.s   V_4
    IL_00e6:  ldarg.0
    IL_00e7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00ec:  leave.s    IL_0161
    IL_00ee:  ldarg.0
    IL_00ef:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00f4:  stloc.s    V_4
    IL_00f6:  ldarg.0
    IL_00f7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00fc:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0102:  ldarg.0
    IL_0103:  ldc.i4.m1
    IL_0104:  dup
    IL_0105:  stloc.0
    IL_0106:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_010b:  ldloca.s   V_4
    IL_010d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0112:  stloc.3
    IL_0113:  ldarg.0
    IL_0114:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0119:  ldarg.0
    IL_011a:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_011f:  ldloc.3
    IL_0120:  newobj     ""int?..ctor(int)""
    IL_0125:  dup
    IL_0126:  stloc.s    V_5
    IL_0128:  constrained. ""T""
    IL_012e:  callvirt   ""void IMoveable.this[int].set""
    IL_0133:  leave.s    IL_014e
  }
  catch System.Exception
  {
    IL_0135:  stloc.s    V_6
    IL_0137:  ldarg.0
    IL_0138:  ldc.i4.s   -2
    IL_013a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_013f:  ldarg.0
    IL_0140:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0145:  ldloc.s    V_6
    IL_0147:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_014c:  leave.s    IL_0161
  }
  IL_014e:  ldarg.0
  IL_014f:  ldc.i4.s   -2
  IL_0151:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0156:  ldarg.0
  IL_0157:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_015c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0161:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_Property_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    int Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        (item.Position, _) = (GetOffset(ref item), 1);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        (item.Position, _) = (GetOffset(ref item), 1);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position set for item '1'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       25 (0x19)
  .maxstack  2
  .locals init (T V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloca.s   V_0
  IL_0004:  ldarga.s   V_0
  IL_0006:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000b:  stloc.1
  IL_000c:  ldloc.1
  IL_000d:  constrained. ""T""
  IL_0013:  callvirt   ""void IMoveable.Position.set""
  IL_0018:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       52 (0x34)
  .maxstack  2
  .locals init (T V_0,
                T& V_1,
                T V_2,
                int V_3)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.1
  IL_0003:  ldloca.s   V_2
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.2
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.1
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.0
  IL_001a:  ldloca.s   V_0
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.1
  IL_001f:  ldarga.s   V_0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.3
  IL_0028:  constrained. ""T""
  IL_002e:  callvirt   ""void IMoveable.Position.set""
  IL_0033:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_Property_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    int Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        (item.Position, _) = (GetOffset(ref item), 1);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        (item.Position, _) = (GetOffset(ref item), 1);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position set for item '-1'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       23 (0x17)
  .maxstack  2
  .locals init (int V_0)
  IL_0000:  ldarga.s   V_0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.0
  IL_000a:  ldloc.0
  IL_000b:  constrained. ""T""
  IL_0011:  callvirt   ""void IMoveable.Position.set""
  IL_0016:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_Property_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        (item.Position, _) = (GetOffset(ref item), 1);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        (item.Position, _) = (GetOffset(ref item), 1);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position set for item '1'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       29 (0x1d)
  .maxstack  2
  .locals init (T V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldloca.s   V_0
  IL_0009:  ldarg.0
  IL_000a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000f:  stloc.1
  IL_0010:  ldloc.1
  IL_0011:  constrained. ""T""
  IL_0017:  callvirt   ""void IMoveable.Position.set""
  IL_001c:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       50 (0x32)
  .maxstack  2
  .locals init (T V_0,
                T& V_1,
                T V_2,
                int V_3)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_2
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.2
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_001d
  IL_0012:  ldloc.1
  IL_0013:  ldobj      ""T""
  IL_0018:  stloc.0
  IL_0019:  ldloca.s   V_0
  IL_001b:  br.s       IL_001e
  IL_001d:  ldloc.1
  IL_001e:  ldarg.0
  IL_001f:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0024:  stloc.3
  IL_0025:  ldloc.3
  IL_0026:  constrained. ""T""
  IL_002c:  callvirt   ""void IMoveable.Position.set""
  IL_0031:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_Property_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        (item.Position, _) = (GetOffset(ref item), 1);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        (item.Position, _) = (GetOffset(ref item), 1);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position set for item '-1'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       21 (0x15)
  .maxstack  2
  .locals init (int V_0)
  IL_0000:  ldarg.0
  IL_0001:  ldarg.0
  IL_0002:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0007:  stloc.0
  IL_0008:  ldloc.0
  IL_0009:  constrained. ""T""
  IL_000f:  callvirt   ""void IMoveable.Position.set""
  IL_0014:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_Property_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int Position {get;set;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        (item.Position, _) = (await GetOffsetAsync(GetOffset(ref item)), 1);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        (item.Position, _) = (await GetOffsetAsync(GetOffset(ref item)), 1);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position set for item '1'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      195 (0xc3)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0055
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.2
    IL_002c:  ldloca.s   V_2
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0071
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.2
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_2
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0053:  leave.s    IL_00c2
    IL_0055:  ldarg.0
    IL_0056:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005b:  stloc.2
    IL_005c:  ldarg.0
    IL_005d:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0062:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0068:  ldarg.0
    IL_0069:  ldc.i4.m1
    IL_006a:  dup
    IL_006b:  stloc.0
    IL_006c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0071:  ldloca.s   V_2
    IL_0073:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0078:  stloc.1
    IL_0079:  ldarg.0
    IL_007a:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_007f:  box        ""T""
    IL_0084:  ldloc.1
    IL_0085:  callvirt   ""void IMoveable.Position.set""
    IL_008a:  ldarg.0
    IL_008b:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0090:  initobj    ""T""
    IL_0096:  leave.s    IL_00af
  }
  catch System.Exception
  {
    IL_0098:  stloc.3
    IL_0099:  ldarg.0
    IL_009a:  ldc.i4.s   -2
    IL_009c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00a7:  ldloc.3
    IL_00a8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ad:  leave.s    IL_00c2
  }
  IL_00af:  ldarg.0
  IL_00b0:  ldc.i4.s   -2
  IL_00b2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00b7:  ldarg.0
  IL_00b8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00bd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00c2:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      241 (0xf1)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0068
    IL_000a:  ldloca.s   V_2
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.2
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.3
    IL_003c:  ldloca.s   V_3
    IL_003e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0043:  brtrue.s   IL_0084
    IL_0045:  ldarg.0
    IL_0046:  ldc.i4.0
    IL_0047:  dup
    IL_0048:  stloc.0
    IL_0049:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_004e:  ldarg.0
    IL_004f:  ldloc.3
    IL_0050:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005b:  ldloca.s   V_3
    IL_005d:  ldarg.0
    IL_005e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0063:  leave      IL_00f0
    IL_0068:  ldarg.0
    IL_0069:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_006e:  stloc.3
    IL_006f:  ldarg.0
    IL_0070:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0075:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007b:  ldarg.0
    IL_007c:  ldc.i4.m1
    IL_007d:  dup
    IL_007e:  stloc.0
    IL_007f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0084:  ldloca.s   V_3
    IL_0086:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008b:  stloc.1
    IL_008c:  ldloca.s   V_2
    IL_008e:  initobj    ""T""
    IL_0094:  ldloc.2
    IL_0095:  box        ""T""
    IL_009a:  brtrue.s   IL_00a4
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a2:  br.s       IL_00aa
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00aa:  ldloc.1
    IL_00ab:  constrained. ""T""
    IL_00b1:  callvirt   ""void IMoveable.Position.set""
    IL_00b6:  ldarg.0
    IL_00b7:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00bc:  initobj    ""T""
    IL_00c2:  leave.s    IL_00dd
  }
  catch System.Exception
  {
    IL_00c4:  stloc.s    V_4
    IL_00c6:  ldarg.0
    IL_00c7:  ldc.i4.s   -2
    IL_00c9:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00ce:  ldarg.0
    IL_00cf:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00d4:  ldloc.s    V_4
    IL_00d6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00db:  leave.s    IL_00f0
  }
  IL_00dd:  ldarg.0
  IL_00de:  ldc.i4.s   -2
  IL_00e0:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_00e5:  ldarg.0
  IL_00e6:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_00eb:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00f0:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_Property_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int Position {get;set;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int Position
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        (item.Position, _) = (await GetOffsetAsync(GetOffset(ref item)), 1);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        (item.Position, _) = (await GetOffsetAsync(GetOffset(ref item)), 1);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position set for item '-1'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      172 (0xac)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0049
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.2
    IL_0020:  ldloca.s   V_2
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0065
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.2
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_2
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0047:  leave.s    IL_00ab
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004f:  stloc.2
    IL_0050:  ldarg.0
    IL_0051:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0056:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005c:  ldarg.0
    IL_005d:  ldc.i4.m1
    IL_005e:  dup
    IL_005f:  stloc.0
    IL_0060:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0065:  ldloca.s   V_2
    IL_0067:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006c:  stloc.1
    IL_006d:  ldarg.0
    IL_006e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0073:  ldloc.1
    IL_0074:  constrained. ""T""
    IL_007a:  callvirt   ""void IMoveable.Position.set""
    IL_007f:  leave.s    IL_0098
  }
  catch System.Exception
  {
    IL_0081:  stloc.3
    IL_0082:  ldarg.0
    IL_0083:  ldc.i4.s   -2
    IL_0085:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_008a:  ldarg.0
    IL_008b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0090:  ldloc.3
    IL_0091:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0096:  leave.s    IL_00ab
  }
  IL_0098:  ldarg.0
  IL_0099:  ldc.i4.s   -2
  IL_009b:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00a0:  ldarg.0
  IL_00a1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00a6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ab:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitIndexIndexer_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        _ = item[^GetOffset(ref item)];
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        _ = item[^GetOffset(ref item)];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position Length for item '2'
Position get for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
   // Code size       36 (0x24)
  .maxstack  3
  .locals init (T V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.1
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  ldloc.0
  IL_0011:  box        ""T""
  IL_0016:  callvirt   ""int IMoveable.Length.get""
  IL_001b:  ldloc.1
  IL_001c:  sub
  IL_001d:  callvirt   ""int IMoveable.this[int].get""
  IL_0022:  pop
  IL_0023:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
   // Code size       69 (0x45)
  .maxstack  3
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_4
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_4
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  ldloc.0
  IL_002b:  constrained. ""T""
  IL_0031:  callvirt   ""int IMoveable.Length.get""
  IL_0036:  ldloc.3
  IL_0037:  sub
  IL_0038:  constrained. ""T""
  IL_003e:  callvirt   ""int IMoveable.this[int].get""
  IL_0043:  pop
  IL_0044:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitIndexIndexer_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        _ = item[^GetOffset(ref item)];
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        _ = item[^GetOffset(ref item)];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position Length for item '-2'
Position get for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       37 (0x25)
  .maxstack  3
  .locals init (int V_0)
  IL_0000:  ldarga.s   V_0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.0
  IL_000a:  dup
  IL_000b:  constrained. ""T""
  IL_0011:  callvirt   ""int IMoveable.Length.get""
  IL_0016:  ldloc.0
  IL_0017:  sub
  IL_0018:  constrained. ""T""
  IL_001e:  callvirt   ""int IMoveable.this[int].get""
  IL_0023:  pop
  IL_0024:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitIndexIndexer_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        _ = item[^GetOffset(ref item)];
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        _ = item[^GetOffset(ref item)];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position Length for item '2'
Position get for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       40 (0x28)
  .maxstack  3
  .locals init (T V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldarg.0
  IL_0008:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000d:  stloc.1
  IL_000e:  ldloc.0
  IL_000f:  box        ""T""
  IL_0014:  ldloc.0
  IL_0015:  box        ""T""
  IL_001a:  callvirt   ""int IMoveable.Length.get""
  IL_001f:  ldloc.1
  IL_0020:  sub
  IL_0021:  callvirt   ""int IMoveable.this[int].get""
  IL_0026:  pop
  IL_0027:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       67 (0x43)
  .maxstack  3
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_4
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_4
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  ldloc.0
  IL_0029:  constrained. ""T""
  IL_002f:  callvirt   ""int IMoveable.Length.get""
  IL_0034:  ldloc.3
  IL_0035:  sub
  IL_0036:  constrained. ""T""
  IL_003c:  callvirt   ""int IMoveable.this[int].get""
  IL_0041:  pop
  IL_0042:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitIndexIndexer_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        _ = item[^GetOffset(ref item)];
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        _ = item[^GetOffset(ref item)];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position Length for item '-2'
Position get for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
 // Code size       35 (0x23)
  .maxstack  3
  .locals init (int V_0)
  IL_0000:  ldarg.0
  IL_0001:  ldarg.0
  IL_0002:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0007:  stloc.0
  IL_0008:  dup
  IL_0009:  constrained. ""T""
  IL_000f:  callvirt   ""int IMoveable.Length.get""
  IL_0014:  ldloc.0
  IL_0015:  sub
  IL_0016:  constrained. ""T""
  IL_001c:  callvirt   ""int IMoveable.this[int].get""
  IL_0021:  pop
  IL_0022:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitIndexIndexer_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        _ = item[^await GetOffsetAsync(GetOffset(ref item))];
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        _ = item[^await GetOffsetAsync(GetOffset(ref item))];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position Length for item '2'
Position get for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      213 (0xd5)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0055
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.2
    IL_002c:  ldloca.s   V_2
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0071
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.2
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_2
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0053:  leave.s    IL_00d4
    IL_0055:  ldarg.0
    IL_0056:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005b:  stloc.2
    IL_005c:  ldarg.0
    IL_005d:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0062:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0068:  ldarg.0
    IL_0069:  ldc.i4.m1
    IL_006a:  dup
    IL_006b:  stloc.0
    IL_006c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0071:  ldloca.s   V_2
    IL_0073:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0078:  stloc.1
    IL_0079:  ldarg.0
    IL_007a:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_007f:  box        ""T""
    IL_0084:  ldarg.0
    IL_0085:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008a:  box        ""T""
    IL_008f:  callvirt   ""int IMoveable.Length.get""
    IL_0094:  ldloc.1
    IL_0095:  sub
    IL_0096:  callvirt   ""int IMoveable.this[int].get""
    IL_009b:  pop
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a2:  initobj    ""T""
    IL_00a8:  leave.s    IL_00c1
  }
  catch System.Exception
  {
    IL_00aa:  stloc.3
    IL_00ab:  ldarg.0
    IL_00ac:  ldc.i4.s   -2
    IL_00ae:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b3:  ldarg.0
    IL_00b4:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00b9:  ldloc.3
    IL_00ba:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00bf:  leave.s    IL_00d4
  }
  IL_00c1:  ldarg.0
  IL_00c2:  ldc.i4.s   -2
  IL_00c4:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00c9:  ldarg.0
  IL_00ca:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00cf:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00d4:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      284 (0x11c)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0068
    IL_000a:  ldloca.s   V_2
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.2
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.3
    IL_003c:  ldloca.s   V_3
    IL_003e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0043:  brtrue.s   IL_0084
    IL_0045:  ldarg.0
    IL_0046:  ldc.i4.0
    IL_0047:  dup
    IL_0048:  stloc.0
    IL_0049:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_004e:  ldarg.0
    IL_004f:  ldloc.3
    IL_0050:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005b:  ldloca.s   V_3
    IL_005d:  ldarg.0
    IL_005e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0063:  leave      IL_011b
    IL_0068:  ldarg.0
    IL_0069:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_006e:  stloc.3
    IL_006f:  ldarg.0
    IL_0070:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0075:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007b:  ldarg.0
    IL_007c:  ldc.i4.m1
    IL_007d:  dup
    IL_007e:  stloc.0
    IL_007f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0084:  ldloca.s   V_3
    IL_0086:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008b:  stloc.1
    IL_008c:  ldloca.s   V_2
    IL_008e:  initobj    ""T""
    IL_0094:  ldloc.2
    IL_0095:  box        ""T""
    IL_009a:  brtrue.s   IL_00a4
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a2:  br.s       IL_00aa
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00aa:  ldloca.s   V_2
    IL_00ac:  initobj    ""T""
    IL_00b2:  ldloc.2
    IL_00b3:  box        ""T""
    IL_00b8:  brtrue.s   IL_00c2
    IL_00ba:  ldarg.0
    IL_00bb:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00c0:  br.s       IL_00c8
    IL_00c2:  ldarg.0
    IL_00c3:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00c8:  constrained. ""T""
    IL_00ce:  callvirt   ""int IMoveable.Length.get""
    IL_00d3:  ldloc.1
    IL_00d4:  sub
    IL_00d5:  constrained. ""T""
    IL_00db:  callvirt   ""int IMoveable.this[int].get""
    IL_00e0:  pop
    IL_00e1:  ldarg.0
    IL_00e2:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00e7:  initobj    ""T""
    IL_00ed:  leave.s    IL_0108
  }
  catch System.Exception
  {
    IL_00ef:  stloc.s    V_4
    IL_00f1:  ldarg.0
    IL_00f2:  ldc.i4.s   -2
    IL_00f4:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00f9:  ldarg.0
    IL_00fa:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00ff:  ldloc.s    V_4
    IL_0101:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0106:  leave.s    IL_011b
  }
  IL_0108:  ldarg.0
  IL_0109:  ldc.i4.s   -2
  IL_010b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0110:  ldarg.0
  IL_0111:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0116:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_011b:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitIndexIndexer_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        _ = item[^await GetOffsetAsync(GetOffset(ref item))];
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        _ = item[^await GetOffsetAsync(GetOffset(ref item))];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position Length for item '-2'
Position get for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      191 (0xbf)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0049
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.2
    IL_0020:  ldloca.s   V_2
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0065
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.2
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_2
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0047:  leave.s    IL_00be
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004f:  stloc.2
    IL_0050:  ldarg.0
    IL_0051:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0056:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005c:  ldarg.0
    IL_005d:  ldc.i4.m1
    IL_005e:  dup
    IL_005f:  stloc.0
    IL_0060:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0065:  ldloca.s   V_2
    IL_0067:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006c:  stloc.1
    IL_006d:  ldarg.0
    IL_006e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0079:  constrained. ""T""
    IL_007f:  callvirt   ""int IMoveable.Length.get""
    IL_0084:  ldloc.1
    IL_0085:  sub
    IL_0086:  constrained. ""T""
    IL_008c:  callvirt   ""int IMoveable.this[int].get""
    IL_0091:  pop
    IL_0092:  leave.s    IL_00ab
  }
  catch System.Exception
  {
    IL_0094:  stloc.3
    IL_0095:  ldarg.0
    IL_0096:  ldc.i4.s   -2
    IL_0098:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_009d:  ldarg.0
    IL_009e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00a3:  ldloc.3
    IL_00a4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00a9:  leave.s    IL_00be
  }
  IL_00ab:  ldarg.0
  IL_00ac:  ldc.i4.s   -2
  IL_00ae:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00b3:  ldarg.0
  IL_00b4:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00b9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00be:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_Index()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       51 (0x33)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.1
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  callvirt   ""int IMoveable.Length.get""
  IL_0015:  ldloc.1
  IL_0016:  sub
  IL_0017:  stloc.2
  IL_0018:  ldloc.0
  IL_0019:  box        ""T""
  IL_001e:  ldloc.2
  IL_001f:  ldloc.0
  IL_0020:  box        ""T""
  IL_0025:  ldloc.2
  IL_0026:  callvirt   ""int IMoveable.this[int].get""
  IL_002b:  ldc.i4.1
  IL_002c:  add
  IL_002d:  callvirt   ""void IMoveable.this[int].set""
  IL_0032:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       88 (0x58)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int V_4,
                T V_5)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_5
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_5
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  constrained. ""T""
  IL_0030:  callvirt   ""int IMoveable.Length.get""
  IL_0035:  ldloc.3
  IL_0036:  sub
  IL_0037:  stloc.s    V_4
  IL_0039:  ldloc.0
  IL_003a:  ldloc.s    V_4
  IL_003c:  ldloc.0
  IL_003d:  ldloc.s    V_4
  IL_003f:  constrained. ""T""
  IL_0045:  callvirt   ""int IMoveable.this[int].get""
  IL_004a:  ldc.i4.1
  IL_004b:  add
  IL_004c:  constrained. ""T""
  IL_0052:  callvirt   ""void IMoveable.this[int].set""
  IL_0057:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_Index()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-1'
Position Length for item '-2'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       55 (0x37)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int IMoveable.Length.get""
  IL_0017:  ldloc.1
  IL_0018:  sub
  IL_0019:  stloc.2
  IL_001a:  ldloc.0
  IL_001b:  ldloc.2
  IL_001c:  ldloc.0
  IL_001d:  ldloc.2
  IL_001e:  constrained. ""T""
  IL_0024:  callvirt   ""int IMoveable.this[int].get""
  IL_0029:  ldc.i4.1
  IL_002a:  add
  IL_002b:  constrained. ""T""
  IL_0031:  callvirt   ""void IMoveable.this[int].set""
  IL_0036:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_Index_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       55 (0x37)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldarg.0
  IL_0008:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000d:  stloc.1
  IL_000e:  ldloc.0
  IL_000f:  box        ""T""
  IL_0014:  callvirt   ""int IMoveable.Length.get""
  IL_0019:  ldloc.1
  IL_001a:  sub
  IL_001b:  stloc.2
  IL_001c:  ldloc.0
  IL_001d:  box        ""T""
  IL_0022:  ldloc.2
  IL_0023:  ldloc.0
  IL_0024:  box        ""T""
  IL_0029:  ldloc.2
  IL_002a:  callvirt   ""int IMoveable.this[int].get""
  IL_002f:  ldc.i4.1
  IL_0030:  add
  IL_0031:  callvirt   ""void IMoveable.this[int].set""
  IL_0036:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       86 (0x56)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int V_4,
                T V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_5
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_5
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  constrained. ""T""
  IL_002e:  callvirt   ""int IMoveable.Length.get""
  IL_0033:  ldloc.3
  IL_0034:  sub
  IL_0035:  stloc.s    V_4
  IL_0037:  ldloc.0
  IL_0038:  ldloc.s    V_4
  IL_003a:  ldloc.0
  IL_003b:  ldloc.s    V_4
  IL_003d:  constrained. ""T""
  IL_0043:  callvirt   ""int IMoveable.this[int].get""
  IL_0048:  ldc.i4.1
  IL_0049:  add
  IL_004a:  constrained. ""T""
  IL_0050:  callvirt   ""void IMoveable.this[int].set""
  IL_0055:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_Index_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] += 1;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-1'
Position Length for item '-2'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       53 (0x35)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  constrained. ""T""
  IL_0010:  callvirt   ""int IMoveable.Length.get""
  IL_0015:  ldloc.1
  IL_0016:  sub
  IL_0017:  stloc.2
  IL_0018:  ldloc.0
  IL_0019:  ldloc.2
  IL_001a:  ldloc.0
  IL_001b:  ldloc.2
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""int IMoveable.this[int].get""
  IL_0027:  ldc.i4.1
  IL_0028:  add
  IL_0029:  constrained. ""T""
  IL_002f:  callvirt   ""void IMoveable.this[int].set""
  IL_0034:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_Index_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      238 (0xee)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0058
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.3
    IL_002c:  ldloca.s   V_3
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0074
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.3
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_3
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0053:  leave      IL_00ed
    IL_0058:  ldarg.0
    IL_0059:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005e:  stloc.3
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0065:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006b:  ldarg.0
    IL_006c:  ldc.i4.m1
    IL_006d:  dup
    IL_006e:  stloc.0
    IL_006f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0074:  ldloca.s   V_3
    IL_0076:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007b:  stloc.1
    IL_007c:  ldarg.0
    IL_007d:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0082:  box        ""T""
    IL_0087:  callvirt   ""int IMoveable.Length.get""
    IL_008c:  ldloc.1
    IL_008d:  sub
    IL_008e:  stloc.2
    IL_008f:  ldarg.0
    IL_0090:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0095:  box        ""T""
    IL_009a:  ldloc.2
    IL_009b:  ldarg.0
    IL_009c:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a1:  box        ""T""
    IL_00a6:  ldloc.2
    IL_00a7:  callvirt   ""int IMoveable.this[int].get""
    IL_00ac:  ldc.i4.1
    IL_00ad:  add
    IL_00ae:  callvirt   ""void IMoveable.this[int].set""
    IL_00b3:  ldarg.0
    IL_00b4:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b9:  initobj    ""T""
    IL_00bf:  leave.s    IL_00da
  }
  catch System.Exception
  {
    IL_00c1:  stloc.s    V_4
    IL_00c3:  ldarg.0
    IL_00c4:  ldc.i4.s   -2
    IL_00c6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00cb:  ldarg.0
    IL_00cc:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00d1:  ldloc.s    V_4
    IL_00d3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d8:  leave.s    IL_00ed
  }
  IL_00da:  ldarg.0
  IL_00db:  ldc.i4.s   -2
  IL_00dd:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00e2:  ldarg.0
  IL_00e3:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00e8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ed:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      332 (0x14c)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006a
    IL_000a:  ldloca.s   V_3
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.3
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.s    V_4
    IL_003d:  ldloca.s   V_4
    IL_003f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0044:  brtrue.s   IL_0087
    IL_0046:  ldarg.0
    IL_0047:  ldc.i4.0
    IL_0048:  dup
    IL_0049:  stloc.0
    IL_004a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_004f:  ldarg.0
    IL_0050:  ldloc.s    V_4
    IL_0052:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0057:  ldarg.0
    IL_0058:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005d:  ldloca.s   V_4
    IL_005f:  ldarg.0
    IL_0060:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0065:  leave      IL_014b
    IL_006a:  ldarg.0
    IL_006b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0070:  stloc.s    V_4
    IL_0072:  ldarg.0
    IL_0073:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0078:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007e:  ldarg.0
    IL_007f:  ldc.i4.m1
    IL_0080:  dup
    IL_0081:  stloc.0
    IL_0082:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0087:  ldloca.s   V_4
    IL_0089:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008e:  stloc.1
    IL_008f:  ldloca.s   V_3
    IL_0091:  initobj    ""T""
    IL_0097:  ldloc.3
    IL_0098:  box        ""T""
    IL_009d:  brtrue.s   IL_00a7
    IL_009f:  ldarg.0
    IL_00a0:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a5:  br.s       IL_00ad
    IL_00a7:  ldarg.0
    IL_00a8:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00ad:  constrained. ""T""
    IL_00b3:  callvirt   ""int IMoveable.Length.get""
    IL_00b8:  ldloc.1
    IL_00b9:  sub
    IL_00ba:  stloc.2
    IL_00bb:  ldloca.s   V_3
    IL_00bd:  initobj    ""T""
    IL_00c3:  ldloc.3
    IL_00c4:  box        ""T""
    IL_00c9:  brtrue.s   IL_00d3
    IL_00cb:  ldarg.0
    IL_00cc:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00d1:  br.s       IL_00d9
    IL_00d3:  ldarg.0
    IL_00d4:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00d9:  ldloc.2
    IL_00da:  ldloca.s   V_3
    IL_00dc:  initobj    ""T""
    IL_00e2:  ldloc.3
    IL_00e3:  box        ""T""
    IL_00e8:  brtrue.s   IL_00f2
    IL_00ea:  ldarg.0
    IL_00eb:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f0:  br.s       IL_00f8
    IL_00f2:  ldarg.0
    IL_00f3:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00f8:  ldloc.2
    IL_00f9:  constrained. ""T""
    IL_00ff:  callvirt   ""int IMoveable.this[int].get""
    IL_0104:  ldc.i4.1
    IL_0105:  add
    IL_0106:  constrained. ""T""
    IL_010c:  callvirt   ""void IMoveable.this[int].set""
    IL_0111:  ldarg.0
    IL_0112:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0117:  initobj    ""T""
    IL_011d:  leave.s    IL_0138
  }
  catch System.Exception
  {
    IL_011f:  stloc.s    V_5
    IL_0121:  ldarg.0
    IL_0122:  ldc.i4.s   -2
    IL_0124:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0129:  ldarg.0
    IL_012a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_012f:  ldloc.s    V_5
    IL_0131:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0136:  leave.s    IL_014b
  }
  IL_0138:  ldarg.0
  IL_0139:  ldc.i4.s   -2
  IL_013b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0140:  ldarg.0
  IL_0141:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0146:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_014b:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_Index_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-1'
Position Length for item '-2'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      217 (0xd9)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004c
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.3
    IL_0020:  ldloca.s   V_3
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0068
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.3
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_3
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0047:  leave      IL_00d8
    IL_004c:  ldarg.0
    IL_004d:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0052:  stloc.3
    IL_0053:  ldarg.0
    IL_0054:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0059:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005f:  ldarg.0
    IL_0060:  ldc.i4.m1
    IL_0061:  dup
    IL_0062:  stloc.0
    IL_0063:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0068:  ldloca.s   V_3
    IL_006a:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006f:  stloc.1
    IL_0070:  ldarg.0
    IL_0071:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0076:  constrained. ""T""
    IL_007c:  callvirt   ""int IMoveable.Length.get""
    IL_0081:  ldloc.1
    IL_0082:  sub
    IL_0083:  stloc.2
    IL_0084:  ldarg.0
    IL_0085:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008a:  ldloc.2
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0091:  ldloc.2
    IL_0092:  constrained. ""T""
    IL_0098:  callvirt   ""int IMoveable.this[int].get""
    IL_009d:  ldc.i4.1
    IL_009e:  add
    IL_009f:  constrained. ""T""
    IL_00a5:  callvirt   ""void IMoveable.this[int].set""
    IL_00aa:  leave.s    IL_00c5
  }
  catch System.Exception
  {
    IL_00ac:  stloc.s    V_4
    IL_00ae:  ldarg.0
    IL_00af:  ldc.i4.s   -2
    IL_00b1:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b6:  ldarg.0
    IL_00b7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00bc:  ldloc.s    V_4
    IL_00be:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00c3:  leave.s    IL_00d8
  }
  IL_00c5:  ldarg.0
  IL_00c6:  ldc.i4.s   -2
  IL_00c8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00cd:  ldarg.0
  IL_00ce:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00d3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00d8:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_Value()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[^1] += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^1] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       49 (0x31)
  .maxstack  4
  .locals init (T V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  box        ""T""
  IL_0008:  callvirt   ""int IMoveable.Length.get""
  IL_000d:  ldc.i4.1
  IL_000e:  sub
  IL_000f:  stloc.1
  IL_0010:  ldloc.0
  IL_0011:  box        ""T""
  IL_0016:  ldloc.1
  IL_0017:  ldloc.0
  IL_0018:  box        ""T""
  IL_001d:  ldloc.1
  IL_001e:  callvirt   ""int IMoveable.this[int].get""
  IL_0023:  ldarga.s   V_0
  IL_0025:  call       ""int Program.GetOffset<T>(ref T)""
  IL_002a:  add
  IL_002b:  callvirt   ""void IMoveable.this[int].set""
  IL_0030:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       83 (0x53)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_4
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_4
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldloc.0
  IL_0022:  constrained. ""T""
  IL_0028:  callvirt   ""int IMoveable.Length.get""
  IL_002d:  ldc.i4.1
  IL_002e:  sub
  IL_002f:  stloc.3
  IL_0030:  ldloc.0
  IL_0031:  ldloc.3
  IL_0032:  ldloc.0
  IL_0033:  ldloc.3
  IL_0034:  constrained. ""T""
  IL_003a:  callvirt   ""int IMoveable.this[int].get""
  IL_003f:  ldarga.s   V_0
  IL_0041:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0046:  add
  IL_0047:  constrained. ""T""
  IL_004d:  callvirt   ""void IMoveable.this[int].set""
  IL_0052:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_Value()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^1] += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^1] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '-1'
Position Length for item '2'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       53 (0x35)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldloc.0
  IL_0004:  constrained. ""T""
  IL_000a:  callvirt   ""int IMoveable.Length.get""
  IL_000f:  ldc.i4.1
  IL_0010:  sub
  IL_0011:  stloc.1
  IL_0012:  ldloc.0
  IL_0013:  ldloc.1
  IL_0014:  ldloc.0
  IL_0015:  ldloc.1
  IL_0016:  constrained. ""T""
  IL_001c:  callvirt   ""int IMoveable.this[int].get""
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  add
  IL_0029:  constrained. ""T""
  IL_002f:  callvirt   ""void IMoveable.this[int].set""
  IL_0034:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_Value_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[^1] += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^1] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       53 (0x35)
  .maxstack  4
  .locals init (T V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldloc.0
  IL_0008:  box        ""T""
  IL_000d:  callvirt   ""int IMoveable.Length.get""
  IL_0012:  ldc.i4.1
  IL_0013:  sub
  IL_0014:  stloc.1
  IL_0015:  ldloc.0
  IL_0016:  box        ""T""
  IL_001b:  ldloc.1
  IL_001c:  ldloc.0
  IL_001d:  box        ""T""
  IL_0022:  ldloc.1
  IL_0023:  callvirt   ""int IMoveable.this[int].get""
  IL_0028:  ldarg.0
  IL_0029:  call       ""int Program.GetOffset<T>(ref T)""
  IL_002e:  add
  IL_002f:  callvirt   ""void IMoveable.this[int].set""
  IL_0034:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       81 (0x51)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_4
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_4
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldloc.0
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""int IMoveable.Length.get""
  IL_002c:  ldc.i4.1
  IL_002d:  sub
  IL_002e:  stloc.3
  IL_002f:  ldloc.0
  IL_0030:  ldloc.3
  IL_0031:  ldloc.0
  IL_0032:  ldloc.3
  IL_0033:  constrained. ""T""
  IL_0039:  callvirt   ""int IMoveable.this[int].get""
  IL_003e:  ldarg.0
  IL_003f:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0044:  add
  IL_0045:  constrained. ""T""
  IL_004b:  callvirt   ""void IMoveable.this[int].set""
  IL_0050:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_Value_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[^1] += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^1] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '-1'
Position Length for item '2'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       51 (0x33)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  constrained. ""T""
  IL_0009:  callvirt   ""int IMoveable.Length.get""
  IL_000e:  ldc.i4.1
  IL_000f:  sub
  IL_0010:  stloc.1
  IL_0011:  ldloc.0
  IL_0012:  ldloc.1
  IL_0013:  ldloc.0
  IL_0014:  ldloc.1
  IL_0015:  constrained. ""T""
  IL_001b:  callvirt   ""int IMoveable.this[int].get""
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  add
  IL_0027:  constrained. ""T""
  IL_002d:  callvirt   ""void IMoveable.this[int].set""
  IL_0032:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_Value_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^1] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^1] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      254 (0xfe)
  .maxstack  4
  .locals init (int V_0,
                T V_1,
                int V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0080
    IL_000a:  ldarg.0
    IL_000b:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  stloc.1
    IL_0011:  ldloc.1
    IL_0012:  box        ""T""
    IL_0017:  callvirt   ""int IMoveable.Length.get""
    IL_001c:  ldc.i4.1
    IL_001d:  sub
    IL_001e:  stloc.2
    IL_001f:  ldarg.0
    IL_0020:  ldloc.1
    IL_0021:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldloc.2
    IL_0028:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_002d:  ldarg.0
    IL_002e:  ldloc.1
    IL_002f:  box        ""T""
    IL_0034:  ldloc.2
    IL_0035:  callvirt   ""int IMoveable.this[int].get""
    IL_003a:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_003f:  ldarg.0
    IL_0040:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0045:  call       ""int Program.GetOffset<T>(ref T)""
    IL_004a:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_004f:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0054:  stloc.s    V_4
    IL_0056:  ldloca.s   V_4
    IL_0058:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_005d:  brtrue.s   IL_009d
    IL_005f:  ldarg.0
    IL_0060:  ldc.i4.0
    IL_0061:  dup
    IL_0062:  stloc.0
    IL_0063:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0068:  ldarg.0
    IL_0069:  ldloc.s    V_4
    IL_006b:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0070:  ldarg.0
    IL_0071:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0076:  ldloca.s   V_4
    IL_0078:  ldarg.0
    IL_0079:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_007e:  leave.s    IL_00fd
    IL_0080:  ldarg.0
    IL_0081:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0086:  stloc.s    V_4
    IL_0088:  ldarg.0
    IL_0089:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_008e:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0094:  ldarg.0
    IL_0095:  ldc.i4.m1
    IL_0096:  dup
    IL_0097:  stloc.0
    IL_0098:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_009d:  ldloca.s   V_4
    IL_009f:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00a4:  stloc.3
    IL_00a5:  ldarg.0
    IL_00a6:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00ab:  box        ""T""
    IL_00b0:  ldarg.0
    IL_00b1:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00b6:  ldarg.0
    IL_00b7:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_00bc:  ldloc.3
    IL_00bd:  add
    IL_00be:  callvirt   ""void IMoveable.this[int].set""
    IL_00c3:  ldarg.0
    IL_00c4:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00c9:  initobj    ""T""
    IL_00cf:  leave.s    IL_00ea
  }
  catch System.Exception
  {
    IL_00d1:  stloc.s    V_5
    IL_00d3:  ldarg.0
    IL_00d4:  ldc.i4.s   -2
    IL_00d6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00db:  ldarg.0
    IL_00dc:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e1:  ldloc.s    V_5
    IL_00e3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00e8:  leave.s    IL_00fd
  }
  IL_00ea:  ldarg.0
  IL_00eb:  ldc.i4.s   -2
  IL_00ed:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00f2:  ldarg.0
  IL_00f3:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00f8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00fd:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      359 (0x167)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00d0
    IL_000d:  ldloca.s   V_3
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.3
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldloca.s   V_3
    IL_002b:  initobj    ""T""
    IL_0031:  ldloc.3
    IL_0032:  box        ""T""
    IL_0037:  brtrue.s   IL_0041
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_003f:  br.s       IL_0047
    IL_0041:  ldarg.0
    IL_0042:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0047:  constrained. ""T""
    IL_004d:  callvirt   ""int IMoveable.Length.get""
    IL_0052:  ldc.i4.1
    IL_0053:  sub
    IL_0054:  stloc.1
    IL_0055:  ldarg.0
    IL_0056:  ldloc.1
    IL_0057:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_005c:  ldarg.0
    IL_005d:  ldloca.s   V_3
    IL_005f:  initobj    ""T""
    IL_0065:  ldloc.3
    IL_0066:  box        ""T""
    IL_006b:  brtrue.s   IL_0075
    IL_006d:  ldarg.0
    IL_006e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0073:  br.s       IL_007b
    IL_0075:  ldarg.0
    IL_0076:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_007b:  ldloc.1
    IL_007c:  constrained. ""T""
    IL_0082:  callvirt   ""int IMoveable.this[int].get""
    IL_0087:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_008c:  ldarg.0
    IL_008d:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0092:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0097:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_009c:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00a1:  stloc.s    V_4
    IL_00a3:  ldloca.s   V_4
    IL_00a5:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00aa:  brtrue.s   IL_00ed
    IL_00ac:  ldarg.0
    IL_00ad:  ldc.i4.0
    IL_00ae:  dup
    IL_00af:  stloc.0
    IL_00b0:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00b5:  ldarg.0
    IL_00b6:  ldloc.s    V_4
    IL_00b8:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00bd:  ldarg.0
    IL_00be:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00c3:  ldloca.s   V_4
    IL_00c5:  ldarg.0
    IL_00c6:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00cb:  leave      IL_0166
    IL_00d0:  ldarg.0
    IL_00d1:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00d6:  stloc.s    V_4
    IL_00d8:  ldarg.0
    IL_00d9:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00de:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00e4:  ldarg.0
    IL_00e5:  ldc.i4.m1
    IL_00e6:  dup
    IL_00e7:  stloc.0
    IL_00e8:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00ed:  ldloca.s   V_4
    IL_00ef:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00f4:  stloc.2
    IL_00f5:  ldloca.s   V_3
    IL_00f7:  initobj    ""T""
    IL_00fd:  ldloc.3
    IL_00fe:  box        ""T""
    IL_0103:  brtrue.s   IL_010d
    IL_0105:  ldarg.0
    IL_0106:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_010b:  br.s       IL_0113
    IL_010d:  ldarg.0
    IL_010e:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0113:  ldarg.0
    IL_0114:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0119:  ldarg.0
    IL_011a:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_011f:  ldloc.2
    IL_0120:  add
    IL_0121:  constrained. ""T""
    IL_0127:  callvirt   ""void IMoveable.this[int].set""
    IL_012c:  ldarg.0
    IL_012d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0132:  initobj    ""T""
    IL_0138:  leave.s    IL_0153
  }
  catch System.Exception
  {
    IL_013a:  stloc.s    V_5
    IL_013c:  ldarg.0
    IL_013d:  ldc.i4.s   -2
    IL_013f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0144:  ldarg.0
    IL_0145:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_014a:  ldloc.s    V_5
    IL_014c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0151:  leave.s    IL_0166
  }
  IL_0153:  ldarg.0
  IL_0154:  ldc.i4.s   -2
  IL_0156:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_015b:  ldarg.0
  IL_015c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0161:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0166:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_Value_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^1] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^1] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '-1'
Position Length for item '2'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      238 (0xee)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_007c
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  constrained. ""T""
    IL_0016:  callvirt   ""int IMoveable.Length.get""
    IL_001b:  ldc.i4.1
    IL_001c:  sub
    IL_001d:  stloc.1
    IL_001e:  ldarg.0
    IL_001f:  ldloc.1
    IL_0020:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0025:  ldarg.0
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_002c:  ldloc.1
    IL_002d:  constrained. ""T""
    IL_0033:  callvirt   ""int IMoveable.this[int].get""
    IL_0038:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_003d:  ldarg.0
    IL_003e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0043:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0048:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_004d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0052:  stloc.3
    IL_0053:  ldloca.s   V_3
    IL_0055:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_005a:  brtrue.s   IL_0098
    IL_005c:  ldarg.0
    IL_005d:  ldc.i4.0
    IL_005e:  dup
    IL_005f:  stloc.0
    IL_0060:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0065:  ldarg.0
    IL_0066:  ldloc.3
    IL_0067:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006c:  ldarg.0
    IL_006d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0072:  ldloca.s   V_3
    IL_0074:  ldarg.0
    IL_0075:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_007a:  leave.s    IL_00ed
    IL_007c:  ldarg.0
    IL_007d:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0082:  stloc.3
    IL_0083:  ldarg.0
    IL_0084:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0089:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_008f:  ldarg.0
    IL_0090:  ldc.i4.m1
    IL_0091:  dup
    IL_0092:  stloc.0
    IL_0093:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0098:  ldloca.s   V_3
    IL_009a:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_009f:  stloc.2
    IL_00a0:  ldarg.0
    IL_00a1:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00a6:  ldarg.0
    IL_00a7:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00ac:  ldarg.0
    IL_00ad:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00b2:  ldloc.2
    IL_00b3:  add
    IL_00b4:  constrained. ""T""
    IL_00ba:  callvirt   ""void IMoveable.this[int].set""
    IL_00bf:  leave.s    IL_00da
  }
  catch System.Exception
  {
    IL_00c1:  stloc.s    V_4
    IL_00c3:  ldarg.0
    IL_00c4:  ldc.i4.s   -2
    IL_00c6:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00cb:  ldarg.0
    IL_00cc:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00d1:  ldloc.s    V_4
    IL_00d3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d8:  leave.s    IL_00ed
  }
  IL_00da:  ldarg.0
  IL_00db:  ldc.i4.s   -2
  IL_00dd:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00e2:  ldarg.0
  IL_00e3:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00e8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ed:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_IndexAndValue()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       57 (0x39)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.1
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  callvirt   ""int IMoveable.Length.get""
  IL_0015:  ldloc.1
  IL_0016:  sub
  IL_0017:  stloc.2
  IL_0018:  ldloc.0
  IL_0019:  box        ""T""
  IL_001e:  ldloc.2
  IL_001f:  ldloc.0
  IL_0020:  box        ""T""
  IL_0025:  ldloc.2
  IL_0026:  callvirt   ""int IMoveable.this[int].get""
  IL_002b:  ldarga.s   V_0
  IL_002d:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0032:  add
  IL_0033:  callvirt   ""void IMoveable.this[int].set""
  IL_0038:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       94 (0x5e)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int V_4,
                T V_5)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_5
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_5
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  constrained. ""T""
  IL_0030:  callvirt   ""int IMoveable.Length.get""
  IL_0035:  ldloc.3
  IL_0036:  sub
  IL_0037:  stloc.s    V_4
  IL_0039:  ldloc.0
  IL_003a:  ldloc.s    V_4
  IL_003c:  ldloc.0
  IL_003d:  ldloc.s    V_4
  IL_003f:  constrained. ""T""
  IL_0045:  callvirt   ""int IMoveable.this[int].get""
  IL_004a:  ldarga.s   V_0
  IL_004c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0051:  add
  IL_0052:  constrained. ""T""
  IL_0058:  callvirt   ""void IMoveable.this[int].set""
  IL_005d:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_IndexAndValue()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] += GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       61 (0x3d)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int IMoveable.Length.get""
  IL_0017:  ldloc.1
  IL_0018:  sub
  IL_0019:  stloc.2
  IL_001a:  ldloc.0
  IL_001b:  ldloc.2
  IL_001c:  ldloc.0
  IL_001d:  ldloc.2
  IL_001e:  constrained. ""T""
  IL_0024:  callvirt   ""int IMoveable.this[int].get""
  IL_0029:  ldarga.s   V_0
  IL_002b:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0030:  add
  IL_0031:  constrained. ""T""
  IL_0037:  callvirt   ""void IMoveable.this[int].set""
  IL_003c:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_IndexAndValue_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       60 (0x3c)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldarg.0
  IL_0008:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000d:  stloc.1
  IL_000e:  ldloc.0
  IL_000f:  box        ""T""
  IL_0014:  callvirt   ""int IMoveable.Length.get""
  IL_0019:  ldloc.1
  IL_001a:  sub
  IL_001b:  stloc.2
  IL_001c:  ldloc.0
  IL_001d:  box        ""T""
  IL_0022:  ldloc.2
  IL_0023:  ldloc.0
  IL_0024:  box        ""T""
  IL_0029:  ldloc.2
  IL_002a:  callvirt   ""int IMoveable.this[int].get""
  IL_002f:  ldarg.0
  IL_0030:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0035:  add
  IL_0036:  callvirt   ""void IMoveable.this[int].set""
  IL_003b:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       91 (0x5b)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int V_4,
                T V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_5
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_5
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  constrained. ""T""
  IL_002e:  callvirt   ""int IMoveable.Length.get""
  IL_0033:  ldloc.3
  IL_0034:  sub
  IL_0035:  stloc.s    V_4
  IL_0037:  ldloc.0
  IL_0038:  ldloc.s    V_4
  IL_003a:  ldloc.0
  IL_003b:  ldloc.s    V_4
  IL_003d:  constrained. ""T""
  IL_0043:  callvirt   ""int IMoveable.this[int].get""
  IL_0048:  ldarg.0
  IL_0049:  call       ""int Program.GetOffset<T>(ref T)""
  IL_004e:  add
  IL_004f:  constrained. ""T""
  IL_0055:  callvirt   ""void IMoveable.this[int].set""
  IL_005a:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_IndexAndValue_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] += GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       58 (0x3a)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int V_2)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  constrained. ""T""
  IL_0010:  callvirt   ""int IMoveable.Length.get""
  IL_0015:  ldloc.1
  IL_0016:  sub
  IL_0017:  stloc.2
  IL_0018:  ldloc.0
  IL_0019:  ldloc.2
  IL_001a:  ldloc.0
  IL_001b:  ldloc.2
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""int IMoveable.this[int].get""
  IL_0027:  ldarg.0
  IL_0028:  call       ""int Program.GetOffset<T>(ref T)""
  IL_002d:  add
  IL_002e:  constrained. ""T""
  IL_0034:  callvirt   ""void IMoveable.this[int].set""
  IL_0039:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_IndexAndValue_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      271 (0x10f)
  .maxstack  4
  .locals init (int V_0,
                T V_1,
                int V_2,
                int V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_008f
    IL_000d:  ldarg.0
    IL_000e:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0013:  stloc.1
    IL_0014:  ldarg.0
    IL_0015:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001a:  call       ""int Program.GetOffset<T>(ref T)""
    IL_001f:  stloc.2
    IL_0020:  ldloc.1
    IL_0021:  box        ""T""
    IL_0026:  callvirt   ""int IMoveable.Length.get""
    IL_002b:  ldloc.2
    IL_002c:  sub
    IL_002d:  stloc.3
    IL_002e:  ldarg.0
    IL_002f:  ldloc.1
    IL_0030:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0035:  ldarg.0
    IL_0036:  ldloc.3
    IL_0037:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_003c:  ldarg.0
    IL_003d:  ldloc.1
    IL_003e:  box        ""T""
    IL_0043:  ldloc.3
    IL_0044:  callvirt   ""int IMoveable.this[int].get""
    IL_0049:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_004e:  ldarg.0
    IL_004f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0054:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0059:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_005e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0063:  stloc.s    V_5
    IL_0065:  ldloca.s   V_5
    IL_0067:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_006c:  brtrue.s   IL_00ac
    IL_006e:  ldarg.0
    IL_006f:  ldc.i4.0
    IL_0070:  dup
    IL_0071:  stloc.0
    IL_0072:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0077:  ldarg.0
    IL_0078:  ldloc.s    V_5
    IL_007a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007f:  ldarg.0
    IL_0080:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0085:  ldloca.s   V_5
    IL_0087:  ldarg.0
    IL_0088:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_008d:  leave.s    IL_010e
    IL_008f:  ldarg.0
    IL_0090:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0095:  stloc.s    V_5
    IL_0097:  ldarg.0
    IL_0098:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_009d:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00a3:  ldarg.0
    IL_00a4:  ldc.i4.m1
    IL_00a5:  dup
    IL_00a6:  stloc.0
    IL_00a7:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ac:  ldloca.s   V_5
    IL_00ae:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00b3:  stloc.s    V_4
    IL_00b5:  ldarg.0
    IL_00b6:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00bb:  box        ""T""
    IL_00c0:  ldarg.0
    IL_00c1:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00c6:  ldarg.0
    IL_00c7:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_00cc:  ldloc.s    V_4
    IL_00ce:  add
    IL_00cf:  callvirt   ""void IMoveable.this[int].set""
    IL_00d4:  ldarg.0
    IL_00d5:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00da:  initobj    ""T""
    IL_00e0:  leave.s    IL_00fb
  }
  catch System.Exception
  {
    IL_00e2:  stloc.s    V_6
    IL_00e4:  ldarg.0
    IL_00e5:  ldc.i4.s   -2
    IL_00e7:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ec:  ldarg.0
    IL_00ed:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00f2:  ldloc.s    V_6
    IL_00f4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00f9:  leave.s    IL_010e
  }
  IL_00fb:  ldarg.0
  IL_00fc:  ldc.i4.s   -2
  IL_00fe:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0103:  ldarg.0
  IL_0104:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0109:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_010e:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      375 (0x177)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00df
    IL_000d:  ldloca.s   V_4
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.s    V_4
    IL_0017:  box        ""T""
    IL_001c:  brtrue.s   IL_002a
    IL_001e:  ldarg.0
    IL_001f:  ldarg.0
    IL_0020:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0025:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_002a:  ldarg.0
    IL_002b:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0030:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0035:  stloc.1
    IL_0036:  ldloca.s   V_4
    IL_0038:  initobj    ""T""
    IL_003e:  ldloc.s    V_4
    IL_0040:  box        ""T""
    IL_0045:  brtrue.s   IL_004f
    IL_0047:  ldarg.0
    IL_0048:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_004d:  br.s       IL_0055
    IL_004f:  ldarg.0
    IL_0050:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0055:  constrained. ""T""
    IL_005b:  callvirt   ""int IMoveable.Length.get""
    IL_0060:  ldloc.1
    IL_0061:  sub
    IL_0062:  stloc.2
    IL_0063:  ldarg.0
    IL_0064:  ldloc.2
    IL_0065:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_006a:  ldarg.0
    IL_006b:  ldloca.s   V_4
    IL_006d:  initobj    ""T""
    IL_0073:  ldloc.s    V_4
    IL_0075:  box        ""T""
    IL_007a:  brtrue.s   IL_0084
    IL_007c:  ldarg.0
    IL_007d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0082:  br.s       IL_008a
    IL_0084:  ldarg.0
    IL_0085:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_008a:  ldloc.2
    IL_008b:  constrained. ""T""
    IL_0091:  callvirt   ""int IMoveable.this[int].get""
    IL_0096:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_009b:  ldarg.0
    IL_009c:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00a1:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00a6:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00ab:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00b0:  stloc.s    V_5
    IL_00b2:  ldloca.s   V_5
    IL_00b4:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00b9:  brtrue.s   IL_00fc
    IL_00bb:  ldarg.0
    IL_00bc:  ldc.i4.0
    IL_00bd:  dup
    IL_00be:  stloc.0
    IL_00bf:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00c4:  ldarg.0
    IL_00c5:  ldloc.s    V_5
    IL_00c7:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00cc:  ldarg.0
    IL_00cd:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00d2:  ldloca.s   V_5
    IL_00d4:  ldarg.0
    IL_00d5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00da:  leave      IL_0176
    IL_00df:  ldarg.0
    IL_00e0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00e5:  stloc.s    V_5
    IL_00e7:  ldarg.0
    IL_00e8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00ed:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00f3:  ldarg.0
    IL_00f4:  ldc.i4.m1
    IL_00f5:  dup
    IL_00f6:  stloc.0
    IL_00f7:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00fc:  ldloca.s   V_5
    IL_00fe:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0103:  stloc.3
    IL_0104:  ldloca.s   V_4
    IL_0106:  initobj    ""T""
    IL_010c:  ldloc.s    V_4
    IL_010e:  box        ""T""
    IL_0113:  brtrue.s   IL_011d
    IL_0115:  ldarg.0
    IL_0116:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_011b:  br.s       IL_0123
    IL_011d:  ldarg.0
    IL_011e:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0123:  ldarg.0
    IL_0124:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0129:  ldarg.0
    IL_012a:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_012f:  ldloc.3
    IL_0130:  add
    IL_0131:  constrained. ""T""
    IL_0137:  callvirt   ""void IMoveable.this[int].set""
    IL_013c:  ldarg.0
    IL_013d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0142:  initobj    ""T""
    IL_0148:  leave.s    IL_0163
  }
  catch System.Exception
  {
    IL_014a:  stloc.s    V_6
    IL_014c:  ldarg.0
    IL_014d:  ldc.i4.s   -2
    IL_014f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0154:  ldarg.0
    IL_0155:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_015a:  ldloc.s    V_6
    IL_015c:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0161:  leave.s    IL_0176
  }
  IL_0163:  ldarg.0
  IL_0164:  ldc.i4.s   -2
  IL_0166:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_016b:  ldarg.0
  IL_016c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0171:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0176:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_IndexAndValue_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      256 (0x100)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_008d
    IL_000d:  ldarg.0
    IL_000e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0013:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0018:  stloc.1
    IL_0019:  ldarg.0
    IL_001a:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001f:  constrained. ""T""
    IL_0025:  callvirt   ""int IMoveable.Length.get""
    IL_002a:  ldloc.1
    IL_002b:  sub
    IL_002c:  stloc.2
    IL_002d:  ldarg.0
    IL_002e:  ldloc.2
    IL_002f:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0034:  ldarg.0
    IL_0035:  ldarg.0
    IL_0036:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_003b:  ldloc.2
    IL_003c:  constrained. ""T""
    IL_0042:  callvirt   ""int IMoveable.this[int].get""
    IL_0047:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_004c:  ldarg.0
    IL_004d:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0052:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0057:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_005c:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0061:  stloc.s    V_4
    IL_0063:  ldloca.s   V_4
    IL_0065:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_006a:  brtrue.s   IL_00aa
    IL_006c:  ldarg.0
    IL_006d:  ldc.i4.0
    IL_006e:  dup
    IL_006f:  stloc.0
    IL_0070:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0075:  ldarg.0
    IL_0076:  ldloc.s    V_4
    IL_0078:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007d:  ldarg.0
    IL_007e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0083:  ldloca.s   V_4
    IL_0085:  ldarg.0
    IL_0086:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_008b:  leave.s    IL_00ff
    IL_008d:  ldarg.0
    IL_008e:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0093:  stloc.s    V_4
    IL_0095:  ldarg.0
    IL_0096:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_009b:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00a1:  ldarg.0
    IL_00a2:  ldc.i4.m1
    IL_00a3:  dup
    IL_00a4:  stloc.0
    IL_00a5:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00aa:  ldloca.s   V_4
    IL_00ac:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00b1:  stloc.3
    IL_00b2:  ldarg.0
    IL_00b3:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b8:  ldarg.0
    IL_00b9:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00be:  ldarg.0
    IL_00bf:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00c4:  ldloc.3
    IL_00c5:  add
    IL_00c6:  constrained. ""T""
    IL_00cc:  callvirt   ""void IMoveable.this[int].set""
    IL_00d1:  leave.s    IL_00ec
  }
  catch System.Exception
  {
    IL_00d3:  stloc.s    V_5
    IL_00d5:  ldarg.0
    IL_00d6:  ldc.i4.s   -2
    IL_00d8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00dd:  ldarg.0
    IL_00de:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e3:  ldloc.s    V_5
    IL_00e5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ea:  leave.s    IL_00ff
  }
  IL_00ec:  ldarg.0
  IL_00ed:  ldc.i4.s   -2
  IL_00ef:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00f4:  ldarg.0
  IL_00f5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00fa:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ff:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_IndexAndValue_Async_03()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += GetOffset(ref item);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      248 (0xf8)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0058
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.3
    IL_002c:  ldloca.s   V_3
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0074
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.3
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_3
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0053:  leave      IL_00f7
    IL_0058:  ldarg.0
    IL_0059:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005e:  stloc.3
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0065:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006b:  ldarg.0
    IL_006c:  ldc.i4.m1
    IL_006d:  dup
    IL_006e:  stloc.0
    IL_006f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0074:  ldloca.s   V_3
    IL_0076:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007b:  stloc.1
    IL_007c:  ldarg.0
    IL_007d:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0082:  box        ""T""
    IL_0087:  callvirt   ""int IMoveable.Length.get""
    IL_008c:  ldloc.1
    IL_008d:  sub
    IL_008e:  stloc.2
    IL_008f:  ldarg.0
    IL_0090:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0095:  box        ""T""
    IL_009a:  ldloc.2
    IL_009b:  ldarg.0
    IL_009c:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a1:  box        ""T""
    IL_00a6:  ldloc.2
    IL_00a7:  callvirt   ""int IMoveable.this[int].get""
    IL_00ac:  ldarg.0
    IL_00ad:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b2:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00b7:  add
    IL_00b8:  callvirt   ""void IMoveable.this[int].set""
    IL_00bd:  ldarg.0
    IL_00be:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00c3:  initobj    ""T""
    IL_00c9:  leave.s    IL_00e4
  }
  catch System.Exception
  {
    IL_00cb:  stloc.s    V_4
    IL_00cd:  ldarg.0
    IL_00ce:  ldc.i4.s   -2
    IL_00d0:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00d5:  ldarg.0
    IL_00d6:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00db:  ldloc.s    V_4
    IL_00dd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00e2:  leave.s    IL_00f7
  }
  IL_00e4:  ldarg.0
  IL_00e5:  ldc.i4.s   -2
  IL_00e7:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00ec:  ldarg.0
  IL_00ed:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00f2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00f7:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      342 (0x156)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006a
    IL_000a:  ldloca.s   V_3
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.3
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.s    V_4
    IL_003d:  ldloca.s   V_4
    IL_003f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0044:  brtrue.s   IL_0087
    IL_0046:  ldarg.0
    IL_0047:  ldc.i4.0
    IL_0048:  dup
    IL_0049:  stloc.0
    IL_004a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_004f:  ldarg.0
    IL_0050:  ldloc.s    V_4
    IL_0052:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0057:  ldarg.0
    IL_0058:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005d:  ldloca.s   V_4
    IL_005f:  ldarg.0
    IL_0060:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0065:  leave      IL_0155
    IL_006a:  ldarg.0
    IL_006b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0070:  stloc.s    V_4
    IL_0072:  ldarg.0
    IL_0073:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0078:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007e:  ldarg.0
    IL_007f:  ldc.i4.m1
    IL_0080:  dup
    IL_0081:  stloc.0
    IL_0082:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0087:  ldloca.s   V_4
    IL_0089:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008e:  stloc.1
    IL_008f:  ldloca.s   V_3
    IL_0091:  initobj    ""T""
    IL_0097:  ldloc.3
    IL_0098:  box        ""T""
    IL_009d:  brtrue.s   IL_00a7
    IL_009f:  ldarg.0
    IL_00a0:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a5:  br.s       IL_00ad
    IL_00a7:  ldarg.0
    IL_00a8:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00ad:  constrained. ""T""
    IL_00b3:  callvirt   ""int IMoveable.Length.get""
    IL_00b8:  ldloc.1
    IL_00b9:  sub
    IL_00ba:  stloc.2
    IL_00bb:  ldloca.s   V_3
    IL_00bd:  initobj    ""T""
    IL_00c3:  ldloc.3
    IL_00c4:  box        ""T""
    IL_00c9:  brtrue.s   IL_00d3
    IL_00cb:  ldarg.0
    IL_00cc:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00d1:  br.s       IL_00d9
    IL_00d3:  ldarg.0
    IL_00d4:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00d9:  ldloc.2
    IL_00da:  ldloca.s   V_3
    IL_00dc:  initobj    ""T""
    IL_00e2:  ldloc.3
    IL_00e3:  box        ""T""
    IL_00e8:  brtrue.s   IL_00f2
    IL_00ea:  ldarg.0
    IL_00eb:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f0:  br.s       IL_00f8
    IL_00f2:  ldarg.0
    IL_00f3:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00f8:  ldloc.2
    IL_00f9:  constrained. ""T""
    IL_00ff:  callvirt   ""int IMoveable.this[int].get""
    IL_0104:  ldarg.0
    IL_0105:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_010a:  call       ""int Program.GetOffset<T>(ref T)""
    IL_010f:  add
    IL_0110:  constrained. ""T""
    IL_0116:  callvirt   ""void IMoveable.this[int].set""
    IL_011b:  ldarg.0
    IL_011c:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0121:  initobj    ""T""
    IL_0127:  leave.s    IL_0142
  }
  catch System.Exception
  {
    IL_0129:  stloc.s    V_5
    IL_012b:  ldarg.0
    IL_012c:  ldc.i4.s   -2
    IL_012e:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0133:  ldarg.0
    IL_0134:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0139:  ldloc.s    V_5
    IL_013b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0140:  leave.s    IL_0155
  }
  IL_0142:  ldarg.0
  IL_0143:  ldc.i4.s   -2
  IL_0145:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_014a:  ldarg.0
  IL_014b:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0150:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0155:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_IndexAndValue_Async_03()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += GetOffset(ref item);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      227 (0xe3)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004c
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.3
    IL_0020:  ldloca.s   V_3
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0068
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.3
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_3
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0047:  leave      IL_00e2
    IL_004c:  ldarg.0
    IL_004d:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0052:  stloc.3
    IL_0053:  ldarg.0
    IL_0054:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0059:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005f:  ldarg.0
    IL_0060:  ldc.i4.m1
    IL_0061:  dup
    IL_0062:  stloc.0
    IL_0063:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0068:  ldloca.s   V_3
    IL_006a:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006f:  stloc.1
    IL_0070:  ldarg.0
    IL_0071:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0076:  constrained. ""T""
    IL_007c:  callvirt   ""int IMoveable.Length.get""
    IL_0081:  ldloc.1
    IL_0082:  sub
    IL_0083:  stloc.2
    IL_0084:  ldarg.0
    IL_0085:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008a:  ldloc.2
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0091:  ldloc.2
    IL_0092:  constrained. ""T""
    IL_0098:  callvirt   ""int IMoveable.this[int].get""
    IL_009d:  ldarg.0
    IL_009e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00a3:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00a8:  add
    IL_00a9:  constrained. ""T""
    IL_00af:  callvirt   ""void IMoveable.this[int].set""
    IL_00b4:  leave.s    IL_00cf
  }
  catch System.Exception
  {
    IL_00b6:  stloc.s    V_4
    IL_00b8:  ldarg.0
    IL_00b9:  ldc.i4.s   -2
    IL_00bb:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c0:  ldarg.0
    IL_00c1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00c6:  ldloc.s    V_4
    IL_00c8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00cd:  leave.s    IL_00e2
  }
  IL_00cf:  ldarg.0
  IL_00d0:  ldc.i4.s   -2
  IL_00d2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00d7:  ldarg.0
  IL_00d8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00dd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00e2:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Class_IndexAndValue_Async_04()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      401 (0x191)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0061
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_0107
    IL_0011:  ldarg.0
    IL_0012:  ldarg.0
    IL_0013:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0018:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_001d:  ldarg.0
    IL_001e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0028:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_002d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0032:  stloc.s    V_4
    IL_0034:  ldloca.s   V_4
    IL_0036:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003b:  brtrue.s   IL_007e
    IL_003d:  ldarg.0
    IL_003e:  ldc.i4.0
    IL_003f:  dup
    IL_0040:  stloc.0
    IL_0041:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0046:  ldarg.0
    IL_0047:  ldloc.s    V_4
    IL_0049:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004e:  ldarg.0
    IL_004f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0054:  ldloca.s   V_4
    IL_0056:  ldarg.0
    IL_0057:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_005c:  leave      IL_0190
    IL_0061:  ldarg.0
    IL_0062:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0067:  stloc.s    V_4
    IL_0069:  ldarg.0
    IL_006a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0075:  ldarg.0
    IL_0076:  ldc.i4.m1
    IL_0077:  dup
    IL_0078:  stloc.0
    IL_0079:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007e:  ldloca.s   V_4
    IL_0080:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0085:  stloc.1
    IL_0086:  ldarg.0
    IL_0087:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008c:  box        ""T""
    IL_0091:  callvirt   ""int IMoveable.Length.get""
    IL_0096:  ldloc.1
    IL_0097:  sub
    IL_0098:  stloc.2
    IL_0099:  ldarg.0
    IL_009a:  ldarg.0
    IL_009b:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a0:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00a5:  ldarg.0
    IL_00a6:  ldloc.2
    IL_00a7:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_00ac:  ldarg.0
    IL_00ad:  ldarg.0
    IL_00ae:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b3:  box        ""T""
    IL_00b8:  ldloc.2
    IL_00b9:  callvirt   ""int IMoveable.this[int].get""
    IL_00be:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap4""
    IL_00c3:  ldarg.0
    IL_00c4:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00c9:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00ce:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00d3:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00d8:  stloc.s    V_4
    IL_00da:  ldloca.s   V_4
    IL_00dc:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00e1:  brtrue.s   IL_0124
    IL_00e3:  ldarg.0
    IL_00e4:  ldc.i4.1
    IL_00e5:  dup
    IL_00e6:  stloc.0
    IL_00e7:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ec:  ldarg.0
    IL_00ed:  ldloc.s    V_4
    IL_00ef:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00f4:  ldarg.0
    IL_00f5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00fa:  ldloca.s   V_4
    IL_00fc:  ldarg.0
    IL_00fd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0102:  leave      IL_0190
    IL_0107:  ldarg.0
    IL_0108:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_010d:  stloc.s    V_4
    IL_010f:  ldarg.0
    IL_0110:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0115:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_011b:  ldarg.0
    IL_011c:  ldc.i4.m1
    IL_011d:  dup
    IL_011e:  stloc.0
    IL_011f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0124:  ldloca.s   V_4
    IL_0126:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_012b:  stloc.3
    IL_012c:  ldarg.0
    IL_012d:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0132:  box        ""T""
    IL_0137:  ldarg.0
    IL_0138:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap3""
    IL_013d:  ldarg.0
    IL_013e:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap4""
    IL_0143:  ldloc.3
    IL_0144:  add
    IL_0145:  callvirt   ""void IMoveable.this[int].set""
    IL_014a:  ldarg.0
    IL_014b:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0150:  initobj    ""T""
    IL_0156:  ldarg.0
    IL_0157:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_015c:  initobj    ""T""
    IL_0162:  leave.s    IL_017d
  }
  catch System.Exception
  {
    IL_0164:  stloc.s    V_5
    IL_0166:  ldarg.0
    IL_0167:  ldc.i4.s   -2
    IL_0169:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_016e:  ldarg.0
    IL_016f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0174:  ldloc.s    V_5
    IL_0176:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_017b:  leave.s    IL_0190
  }
  IL_017d:  ldarg.0
  IL_017e:  ldc.i4.s   -2
  IL_0180:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0185:  ldarg.0
  IL_0186:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_018b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0190:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      472 (0x1d8)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0072
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_0140
    IL_0011:  ldloca.s   V_4
    IL_0013:  initobj    ""T""
    IL_0019:  ldloc.s    V_4
    IL_001b:  box        ""T""
    IL_0020:  brtrue.s   IL_002e
    IL_0022:  ldarg.0
    IL_0023:  ldarg.0
    IL_0024:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0029:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_002e:  ldarg.0
    IL_002f:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0034:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0039:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_003e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0043:  stloc.s    V_5
    IL_0045:  ldloca.s   V_5
    IL_0047:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_004c:  brtrue.s   IL_008f
    IL_004e:  ldarg.0
    IL_004f:  ldc.i4.0
    IL_0050:  dup
    IL_0051:  stloc.0
    IL_0052:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0057:  ldarg.0
    IL_0058:  ldloc.s    V_5
    IL_005a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0065:  ldloca.s   V_5
    IL_0067:  ldarg.0
    IL_0068:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_006d:  leave      IL_01d7
    IL_0072:  ldarg.0
    IL_0073:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0078:  stloc.s    V_5
    IL_007a:  ldarg.0
    IL_007b:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0080:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0086:  ldarg.0
    IL_0087:  ldc.i4.m1
    IL_0088:  dup
    IL_0089:  stloc.0
    IL_008a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_008f:  ldloca.s   V_5
    IL_0091:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0096:  stloc.1
    IL_0097:  ldloca.s   V_4
    IL_0099:  initobj    ""T""
    IL_009f:  ldloc.s    V_4
    IL_00a1:  box        ""T""
    IL_00a6:  brtrue.s   IL_00b0
    IL_00a8:  ldarg.0
    IL_00a9:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00ae:  br.s       IL_00b6
    IL_00b0:  ldarg.0
    IL_00b1:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00b6:  constrained. ""T""
    IL_00bc:  callvirt   ""int IMoveable.Length.get""
    IL_00c1:  ldloc.1
    IL_00c2:  sub
    IL_00c3:  stloc.2
    IL_00c4:  ldarg.0
    IL_00c5:  ldloc.2
    IL_00c6:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00cb:  ldarg.0
    IL_00cc:  ldloca.s   V_4
    IL_00ce:  initobj    ""T""
    IL_00d4:  ldloc.s    V_4
    IL_00d6:  box        ""T""
    IL_00db:  brtrue.s   IL_00e5
    IL_00dd:  ldarg.0
    IL_00de:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00e3:  br.s       IL_00eb
    IL_00e5:  ldarg.0
    IL_00e6:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00eb:  ldloc.2
    IL_00ec:  constrained. ""T""
    IL_00f2:  callvirt   ""int IMoveable.this[int].get""
    IL_00f7:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_00fc:  ldarg.0
    IL_00fd:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0102:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0107:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_010c:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0111:  stloc.s    V_5
    IL_0113:  ldloca.s   V_5
    IL_0115:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_011a:  brtrue.s   IL_015d
    IL_011c:  ldarg.0
    IL_011d:  ldc.i4.1
    IL_011e:  dup
    IL_011f:  stloc.0
    IL_0120:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0125:  ldarg.0
    IL_0126:  ldloc.s    V_5
    IL_0128:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_012d:  ldarg.0
    IL_012e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0133:  ldloca.s   V_5
    IL_0135:  ldarg.0
    IL_0136:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_013b:  leave      IL_01d7
    IL_0140:  ldarg.0
    IL_0141:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0146:  stloc.s    V_5
    IL_0148:  ldarg.0
    IL_0149:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_014e:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0154:  ldarg.0
    IL_0155:  ldc.i4.m1
    IL_0156:  dup
    IL_0157:  stloc.0
    IL_0158:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_015d:  ldloca.s   V_5
    IL_015f:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0164:  stloc.3
    IL_0165:  ldloca.s   V_4
    IL_0167:  initobj    ""T""
    IL_016d:  ldloc.s    V_4
    IL_016f:  box        ""T""
    IL_0174:  brtrue.s   IL_017e
    IL_0176:  ldarg.0
    IL_0177:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_017c:  br.s       IL_0184
    IL_017e:  ldarg.0
    IL_017f:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0184:  ldarg.0
    IL_0185:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_018a:  ldarg.0
    IL_018b:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap3""
    IL_0190:  ldloc.3
    IL_0191:  add
    IL_0192:  constrained. ""T""
    IL_0198:  callvirt   ""void IMoveable.this[int].set""
    IL_019d:  ldarg.0
    IL_019e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_01a3:  initobj    ""T""
    IL_01a9:  leave.s    IL_01c4
  }
  catch System.Exception
  {
    IL_01ab:  stloc.s    V_6
    IL_01ad:  ldarg.0
    IL_01ae:  ldc.i4.s   -2
    IL_01b0:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_01b5:  ldarg.0
    IL_01b6:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_01bb:  ldloc.s    V_6
    IL_01bd:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_01c2:  leave.s    IL_01d7
  }
  IL_01c4:  ldarg.0
  IL_01c5:  ldc.i4.s   -2
  IL_01c7:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_01cc:  ldarg.0
  IL_01cd:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_01d2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_01d7:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Compound_ImplicitIndexIndexer_Struct_IndexAndValue_Async_04()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int this[int i] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int this[int i]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return 0;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] += await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      353 (0x161)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0055
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_00ee
    IL_0011:  ldarg.0
    IL_0012:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0017:  call       ""int Program.GetOffset<T>(ref T)""
    IL_001c:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0021:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0026:  stloc.s    V_4
    IL_0028:  ldloca.s   V_4
    IL_002a:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_002f:  brtrue.s   IL_0072
    IL_0031:  ldarg.0
    IL_0032:  ldc.i4.0
    IL_0033:  dup
    IL_0034:  stloc.0
    IL_0035:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003a:  ldarg.0
    IL_003b:  ldloc.s    V_4
    IL_003d:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0042:  ldarg.0
    IL_0043:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0048:  ldloca.s   V_4
    IL_004a:  ldarg.0
    IL_004b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0050:  leave      IL_0160
    IL_0055:  ldarg.0
    IL_0056:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005b:  stloc.s    V_4
    IL_005d:  ldarg.0
    IL_005e:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0063:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0069:  ldarg.0
    IL_006a:  ldc.i4.m1
    IL_006b:  dup
    IL_006c:  stloc.0
    IL_006d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0072:  ldloca.s   V_4
    IL_0074:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0079:  stloc.1
    IL_007a:  ldarg.0
    IL_007b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0080:  constrained. ""T""
    IL_0086:  callvirt   ""int IMoveable.Length.get""
    IL_008b:  ldloc.1
    IL_008c:  sub
    IL_008d:  stloc.2
    IL_008e:  ldarg.0
    IL_008f:  ldloc.2
    IL_0090:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0095:  ldarg.0
    IL_0096:  ldarg.0
    IL_0097:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_009c:  ldloc.2
    IL_009d:  constrained. ""T""
    IL_00a3:  callvirt   ""int IMoveable.this[int].get""
    IL_00a8:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00ad:  ldarg.0
    IL_00ae:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b3:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00b8:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00bd:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00c2:  stloc.s    V_4
    IL_00c4:  ldloca.s   V_4
    IL_00c6:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00cb:  brtrue.s   IL_010b
    IL_00cd:  ldarg.0
    IL_00ce:  ldc.i4.1
    IL_00cf:  dup
    IL_00d0:  stloc.0
    IL_00d1:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00d6:  ldarg.0
    IL_00d7:  ldloc.s    V_4
    IL_00d9:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00de:  ldarg.0
    IL_00df:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e4:  ldloca.s   V_4
    IL_00e6:  ldarg.0
    IL_00e7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00ec:  leave.s    IL_0160
    IL_00ee:  ldarg.0
    IL_00ef:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00f4:  stloc.s    V_4
    IL_00f6:  ldarg.0
    IL_00f7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00fc:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0102:  ldarg.0
    IL_0103:  ldc.i4.m1
    IL_0104:  dup
    IL_0105:  stloc.0
    IL_0106:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_010b:  ldloca.s   V_4
    IL_010d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0112:  stloc.3
    IL_0113:  ldarg.0
    IL_0114:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0119:  ldarg.0
    IL_011a:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_011f:  ldarg.0
    IL_0120:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0125:  ldloc.3
    IL_0126:  add
    IL_0127:  constrained. ""T""
    IL_012d:  callvirt   ""void IMoveable.this[int].set""
    IL_0132:  leave.s    IL_014d
  }
  catch System.Exception
  {
    IL_0134:  stloc.s    V_5
    IL_0136:  ldarg.0
    IL_0137:  ldc.i4.s   -2
    IL_0139:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_013e:  ldarg.0
    IL_013f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0144:  ldloc.s    V_5
    IL_0146:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_014b:  leave.s    IL_0160
  }
  IL_014d:  ldarg.0
  IL_014e:  ldc.i4.s   -2
  IL_0150:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0155:  ldarg.0
  IL_0156:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_015b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0160:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_Index()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] ??= 1;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       82 (0x52)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.1
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  callvirt   ""int IMoveable.Length.get""
  IL_0015:  ldloc.1
  IL_0016:  sub
  IL_0017:  stloc.2
  IL_0018:  ldloc.0
  IL_0019:  box        ""T""
  IL_001e:  ldloc.2
  IL_001f:  callvirt   ""int? IMoveable.this[int].get""
  IL_0024:  stloc.3
  IL_0025:  ldloca.s   V_3
  IL_0027:  call       ""readonly int int?.GetValueOrDefault()""
  IL_002c:  stloc.s    V_4
  IL_002e:  ldloca.s   V_3
  IL_0030:  call       ""readonly bool int?.HasValue.get""
  IL_0035:  brtrue.s   IL_0051
  IL_0037:  ldc.i4.1
  IL_0038:  stloc.s    V_4
  IL_003a:  ldloc.0
  IL_003b:  box        ""T""
  IL_0040:  ldloc.2
  IL_0041:  ldloca.s   V_5
  IL_0043:  ldloc.s    V_4
  IL_0045:  call       ""int?..ctor(int)""
  IL_004a:  ldloc.s    V_5
  IL_004c:  callvirt   ""void IMoveable.this[int].set""
  IL_0051:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      120 (0x78)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int V_4,
                int? V_5,
                int V_6,
                T V_7,
                int? V_8)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_7
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_7
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  constrained. ""T""
  IL_0030:  callvirt   ""int IMoveable.Length.get""
  IL_0035:  ldloc.3
  IL_0036:  sub
  IL_0037:  stloc.s    V_4
  IL_0039:  ldloc.0
  IL_003a:  ldloc.s    V_4
  IL_003c:  constrained. ""T""
  IL_0042:  callvirt   ""int? IMoveable.this[int].get""
  IL_0047:  stloc.s    V_5
  IL_0049:  ldloca.s   V_5
  IL_004b:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0050:  stloc.s    V_6
  IL_0052:  ldloca.s   V_5
  IL_0054:  call       ""readonly bool int?.HasValue.get""
  IL_0059:  brtrue.s   IL_0077
  IL_005b:  ldc.i4.1
  IL_005c:  stloc.s    V_6
  IL_005e:  ldloc.0
  IL_005f:  ldloc.s    V_4
  IL_0061:  ldloca.s   V_8
  IL_0063:  ldloc.s    V_6
  IL_0065:  call       ""int?..ctor(int)""
  IL_006a:  ldloc.s    V_8
  IL_006c:  constrained. ""T""
  IL_0072:  callvirt   ""void IMoveable.this[int].set""
  IL_0077:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_Index()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] ??= 1;
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-1'
Position Length for item '-2'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       86 (0x56)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int IMoveable.Length.get""
  IL_0017:  ldloc.1
  IL_0018:  sub
  IL_0019:  stloc.2
  IL_001a:  ldloc.0
  IL_001b:  ldloc.2
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""int? IMoveable.this[int].get""
  IL_0027:  stloc.3
  IL_0028:  ldloca.s   V_3
  IL_002a:  call       ""readonly int int?.GetValueOrDefault()""
  IL_002f:  stloc.s    V_4
  IL_0031:  ldloca.s   V_3
  IL_0033:  call       ""readonly bool int?.HasValue.get""
  IL_0038:  brtrue.s   IL_0055
  IL_003a:  ldc.i4.1
  IL_003b:  stloc.s    V_4
  IL_003d:  ldloc.0
  IL_003e:  ldloc.2
  IL_003f:  ldloca.s   V_5
  IL_0041:  ldloc.s    V_4
  IL_0043:  call       ""int?..ctor(int)""
  IL_0048:  ldloc.s    V_5
  IL_004a:  constrained. ""T""
  IL_0050:  callvirt   ""void IMoveable.this[int].set""
  IL_0055:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_Index_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] ??= 1;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       86 (0x56)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldarg.0
  IL_0008:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000d:  stloc.1
  IL_000e:  ldloc.0
  IL_000f:  box        ""T""
  IL_0014:  callvirt   ""int IMoveable.Length.get""
  IL_0019:  ldloc.1
  IL_001a:  sub
  IL_001b:  stloc.2
  IL_001c:  ldloc.0
  IL_001d:  box        ""T""
  IL_0022:  ldloc.2
  IL_0023:  callvirt   ""int? IMoveable.this[int].get""
  IL_0028:  stloc.3
  IL_0029:  ldloca.s   V_3
  IL_002b:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0030:  stloc.s    V_4
  IL_0032:  ldloca.s   V_3
  IL_0034:  call       ""readonly bool int?.HasValue.get""
  IL_0039:  brtrue.s   IL_0055
  IL_003b:  ldc.i4.1
  IL_003c:  stloc.s    V_4
  IL_003e:  ldloc.0
  IL_003f:  box        ""T""
  IL_0044:  ldloc.2
  IL_0045:  ldloca.s   V_5
  IL_0047:  ldloc.s    V_4
  IL_0049:  call       ""int?..ctor(int)""
  IL_004e:  ldloc.s    V_5
  IL_0050:  callvirt   ""void IMoveable.this[int].set""
  IL_0055:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      118 (0x76)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int V_4,
                int? V_5,
                int V_6,
                T V_7,
                int? V_8)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_7
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_7
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  constrained. ""T""
  IL_002e:  callvirt   ""int IMoveable.Length.get""
  IL_0033:  ldloc.3
  IL_0034:  sub
  IL_0035:  stloc.s    V_4
  IL_0037:  ldloc.0
  IL_0038:  ldloc.s    V_4
  IL_003a:  constrained. ""T""
  IL_0040:  callvirt   ""int? IMoveable.this[int].get""
  IL_0045:  stloc.s    V_5
  IL_0047:  ldloca.s   V_5
  IL_0049:  call       ""readonly int int?.GetValueOrDefault()""
  IL_004e:  stloc.s    V_6
  IL_0050:  ldloca.s   V_5
  IL_0052:  call       ""readonly bool int?.HasValue.get""
  IL_0057:  brtrue.s   IL_0075
  IL_0059:  ldc.i4.1
  IL_005a:  stloc.s    V_6
  IL_005c:  ldloc.0
  IL_005d:  ldloc.s    V_4
  IL_005f:  ldloca.s   V_8
  IL_0061:  ldloc.s    V_6
  IL_0063:  call       ""int?..ctor(int)""
  IL_0068:  ldloc.s    V_8
  IL_006a:  constrained. ""T""
  IL_0070:  callvirt   ""void IMoveable.this[int].set""
  IL_0075:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_Index_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] ??= 1;
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-1'
Position Length for item '-2'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       84 (0x54)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  constrained. ""T""
  IL_0010:  callvirt   ""int IMoveable.Length.get""
  IL_0015:  ldloc.1
  IL_0016:  sub
  IL_0017:  stloc.2
  IL_0018:  ldloc.0
  IL_0019:  ldloc.2
  IL_001a:  constrained. ""T""
  IL_0020:  callvirt   ""int? IMoveable.this[int].get""
  IL_0025:  stloc.3
  IL_0026:  ldloca.s   V_3
  IL_0028:  call       ""readonly int int?.GetValueOrDefault()""
  IL_002d:  stloc.s    V_4
  IL_002f:  ldloca.s   V_3
  IL_0031:  call       ""readonly bool int?.HasValue.get""
  IL_0036:  brtrue.s   IL_0053
  IL_0038:  ldc.i4.1
  IL_0039:  stloc.s    V_4
  IL_003b:  ldloc.0
  IL_003c:  ldloc.2
  IL_003d:  ldloca.s   V_5
  IL_003f:  ldloc.s    V_4
  IL_0041:  call       ""int?..ctor(int)""
  IL_0046:  ldloc.s    V_5
  IL_0048:  constrained. ""T""
  IL_004e:  callvirt   ""void IMoveable.this[int].set""
  IL_0053:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_Index_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      271 (0x10f)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_005a
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.s    V_5
    IL_002d:  ldloca.s   V_5
    IL_002f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0034:  brtrue.s   IL_0077
    IL_0036:  ldarg.0
    IL_0037:  ldc.i4.0
    IL_0038:  dup
    IL_0039:  stloc.0
    IL_003a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003f:  ldarg.0
    IL_0040:  ldloc.s    V_5
    IL_0042:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0047:  ldarg.0
    IL_0048:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004d:  ldloca.s   V_5
    IL_004f:  ldarg.0
    IL_0050:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0055:  leave      IL_010e
    IL_005a:  ldarg.0
    IL_005b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0060:  stloc.s    V_5
    IL_0062:  ldarg.0
    IL_0063:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006e:  ldarg.0
    IL_006f:  ldc.i4.m1
    IL_0070:  dup
    IL_0071:  stloc.0
    IL_0072:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0077:  ldloca.s   V_5
    IL_0079:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007e:  stloc.1
    IL_007f:  ldarg.0
    IL_0080:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0085:  box        ""T""
    IL_008a:  callvirt   ""int IMoveable.Length.get""
    IL_008f:  ldloc.1
    IL_0090:  sub
    IL_0091:  stloc.2
    IL_0092:  ldarg.0
    IL_0093:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0098:  box        ""T""
    IL_009d:  ldloc.2
    IL_009e:  callvirt   ""int? IMoveable.this[int].get""
    IL_00a3:  stloc.3
    IL_00a4:  ldloca.s   V_3
    IL_00a6:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00ab:  stloc.s    V_4
    IL_00ad:  ldloca.s   V_3
    IL_00af:  call       ""readonly bool int?.HasValue.get""
    IL_00b4:  brtrue.s   IL_00d4
    IL_00b6:  ldc.i4.1
    IL_00b7:  stloc.s    V_4
    IL_00b9:  ldarg.0
    IL_00ba:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00bf:  box        ""T""
    IL_00c4:  ldloc.2
    IL_00c5:  ldloc.s    V_4
    IL_00c7:  newobj     ""int?..ctor(int)""
    IL_00cc:  dup
    IL_00cd:  stloc.s    V_6
    IL_00cf:  callvirt   ""void IMoveable.this[int].set""
    IL_00d4:  ldarg.0
    IL_00d5:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00da:  initobj    ""T""
    IL_00e0:  leave.s    IL_00fb
  }
  catch System.Exception
  {
    IL_00e2:  stloc.s    V_7
    IL_00e4:  ldarg.0
    IL_00e5:  ldc.i4.s   -2
    IL_00e7:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ec:  ldarg.0
    IL_00ed:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00f2:  ldloc.s    V_7
    IL_00f4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00f9:  leave.s    IL_010e
  }
  IL_00fb:  ldarg.0
  IL_00fc:  ldc.i4.s   -2
  IL_00fe:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0103:  ldarg.0
  IL_0104:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0109:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_010e:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      366 (0x16e)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                T V_5,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_6,
                int? V_7,
                System.Exception V_8)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006b
    IL_000a:  ldloca.s   V_5
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.s    V_5
    IL_0014:  box        ""T""
    IL_0019:  brtrue.s   IL_0027
    IL_001b:  ldarg.0
    IL_001c:  ldarg.0
    IL_001d:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0022:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0027:  ldarg.0
    IL_0028:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002d:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0032:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0037:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003c:  stloc.s    V_6
    IL_003e:  ldloca.s   V_6
    IL_0040:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0045:  brtrue.s   IL_0088
    IL_0047:  ldarg.0
    IL_0048:  ldc.i4.0
    IL_0049:  dup
    IL_004a:  stloc.0
    IL_004b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0050:  ldarg.0
    IL_0051:  ldloc.s    V_6
    IL_0053:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  ldarg.0
    IL_0059:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005e:  ldloca.s   V_6
    IL_0060:  ldarg.0
    IL_0061:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0066:  leave      IL_016d
    IL_006b:  ldarg.0
    IL_006c:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0071:  stloc.s    V_6
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0079:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007f:  ldarg.0
    IL_0080:  ldc.i4.m1
    IL_0081:  dup
    IL_0082:  stloc.0
    IL_0083:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0088:  ldloca.s   V_6
    IL_008a:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008f:  stloc.1
    IL_0090:  ldloca.s   V_5
    IL_0092:  initobj    ""T""
    IL_0098:  ldloc.s    V_5
    IL_009a:  box        ""T""
    IL_009f:  brtrue.s   IL_00a9
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a7:  br.s       IL_00af
    IL_00a9:  ldarg.0
    IL_00aa:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00af:  constrained. ""T""
    IL_00b5:  callvirt   ""int IMoveable.Length.get""
    IL_00ba:  ldloc.1
    IL_00bb:  sub
    IL_00bc:  stloc.2
    IL_00bd:  ldloca.s   V_5
    IL_00bf:  initobj    ""T""
    IL_00c5:  ldloc.s    V_5
    IL_00c7:  box        ""T""
    IL_00cc:  brtrue.s   IL_00d6
    IL_00ce:  ldarg.0
    IL_00cf:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00d4:  br.s       IL_00dc
    IL_00d6:  ldarg.0
    IL_00d7:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00dc:  ldloc.2
    IL_00dd:  constrained. ""T""
    IL_00e3:  callvirt   ""int? IMoveable.this[int].get""
    IL_00e8:  stloc.3
    IL_00e9:  ldloca.s   V_3
    IL_00eb:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00f0:  stloc.s    V_4
    IL_00f2:  ldloca.s   V_3
    IL_00f4:  call       ""readonly bool int?.HasValue.get""
    IL_00f9:  brtrue.s   IL_0133
    IL_00fb:  ldc.i4.1
    IL_00fc:  stloc.s    V_4
    IL_00fe:  ldloca.s   V_5
    IL_0100:  initobj    ""T""
    IL_0106:  ldloc.s    V_5
    IL_0108:  box        ""T""
    IL_010d:  brtrue.s   IL_0117
    IL_010f:  ldarg.0
    IL_0110:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0115:  br.s       IL_011d
    IL_0117:  ldarg.0
    IL_0118:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_011d:  ldloc.2
    IL_011e:  ldloc.s    V_4
    IL_0120:  newobj     ""int?..ctor(int)""
    IL_0125:  dup
    IL_0126:  stloc.s    V_7
    IL_0128:  constrained. ""T""
    IL_012e:  callvirt   ""void IMoveable.this[int].set""
    IL_0133:  ldarg.0
    IL_0134:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0139:  initobj    ""T""
    IL_013f:  leave.s    IL_015a
  }
  catch System.Exception
  {
    IL_0141:  stloc.s    V_8
    IL_0143:  ldarg.0
    IL_0144:  ldc.i4.s   -2
    IL_0146:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_014b:  ldarg.0
    IL_014c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0151:  ldloc.s    V_8
    IL_0153:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0158:  leave.s    IL_016d
  }
  IL_015a:  ldarg.0
  IL_015b:  ldc.i4.s   -2
  IL_015d:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0162:  ldarg.0
  IL_0163:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0168:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_016d:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_Index_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= 1;
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-1'
Position Length for item '-2'
Position get for item '-2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      250 (0xfa)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004e
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.s    V_5
    IL_0021:  ldloca.s   V_5
    IL_0023:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0028:  brtrue.s   IL_006b
    IL_002a:  ldarg.0
    IL_002b:  ldc.i4.0
    IL_002c:  dup
    IL_002d:  stloc.0
    IL_002e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0033:  ldarg.0
    IL_0034:  ldloc.s    V_5
    IL_0036:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_003b:  ldarg.0
    IL_003c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0041:  ldloca.s   V_5
    IL_0043:  ldarg.0
    IL_0044:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0049:  leave      IL_00f9
    IL_004e:  ldarg.0
    IL_004f:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0054:  stloc.s    V_5
    IL_0056:  ldarg.0
    IL_0057:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0062:  ldarg.0
    IL_0063:  ldc.i4.m1
    IL_0064:  dup
    IL_0065:  stloc.0
    IL_0066:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_006b:  ldloca.s   V_5
    IL_006d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0072:  stloc.1
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0079:  constrained. ""T""
    IL_007f:  callvirt   ""int IMoveable.Length.get""
    IL_0084:  ldloc.1
    IL_0085:  sub
    IL_0086:  stloc.2
    IL_0087:  ldarg.0
    IL_0088:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008d:  ldloc.2
    IL_008e:  constrained. ""T""
    IL_0094:  callvirt   ""int? IMoveable.this[int].get""
    IL_0099:  stloc.3
    IL_009a:  ldloca.s   V_3
    IL_009c:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00a1:  stloc.s    V_4
    IL_00a3:  ldloca.s   V_3
    IL_00a5:  call       ""readonly bool int?.HasValue.get""
    IL_00aa:  brtrue.s   IL_00cb
    IL_00ac:  ldc.i4.1
    IL_00ad:  stloc.s    V_4
    IL_00af:  ldarg.0
    IL_00b0:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b5:  ldloc.2
    IL_00b6:  ldloc.s    V_4
    IL_00b8:  newobj     ""int?..ctor(int)""
    IL_00bd:  dup
    IL_00be:  stloc.s    V_6
    IL_00c0:  constrained. ""T""
    IL_00c6:  callvirt   ""void IMoveable.this[int].set""
    IL_00cb:  leave.s    IL_00e6
  }
  catch System.Exception
  {
    IL_00cd:  stloc.s    V_7
    IL_00cf:  ldarg.0
    IL_00d0:  ldc.i4.s   -2
    IL_00d2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00d7:  ldarg.0
    IL_00d8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00dd:  ldloc.s    V_7
    IL_00df:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00e4:  leave.s    IL_00f9
  }
  IL_00e6:  ldarg.0
  IL_00e7:  ldc.i4.s   -2
  IL_00e9:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00ee:  ldarg.0
  IL_00ef:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00f4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00f9:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_Value()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[^1] ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^1] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       77 (0x4d)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  box        ""T""
  IL_0008:  callvirt   ""int IMoveable.Length.get""
  IL_000d:  ldc.i4.1
  IL_000e:  sub
  IL_000f:  stloc.1
  IL_0010:  ldloc.0
  IL_0011:  box        ""T""
  IL_0016:  ldloc.1
  IL_0017:  callvirt   ""int? IMoveable.this[int].get""
  IL_001c:  stloc.2
  IL_001d:  ldloca.s   V_2
  IL_001f:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0024:  stloc.3
  IL_0025:  ldloca.s   V_2
  IL_0027:  call       ""readonly bool int?.HasValue.get""
  IL_002c:  brtrue.s   IL_004c
  IL_002e:  ldarga.s   V_0
  IL_0030:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0035:  stloc.3
  IL_0036:  ldloc.0
  IL_0037:  box        ""T""
  IL_003c:  ldloc.1
  IL_003d:  ldloca.s   V_4
  IL_003f:  ldloc.3
  IL_0040:  call       ""int?..ctor(int)""
  IL_0045:  ldloc.s    V_4
  IL_0047:  callvirt   ""void IMoveable.this[int].set""
  IL_004c:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      115 (0x73)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int? V_4,
                int V_5,
                T V_6,
                int? V_7)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_6
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_6
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldloc.0
  IL_0022:  constrained. ""T""
  IL_0028:  callvirt   ""int IMoveable.Length.get""
  IL_002d:  ldc.i4.1
  IL_002e:  sub
  IL_002f:  stloc.3
  IL_0030:  ldloc.0
  IL_0031:  ldloc.3
  IL_0032:  constrained. ""T""
  IL_0038:  callvirt   ""int? IMoveable.this[int].get""
  IL_003d:  stloc.s    V_4
  IL_003f:  ldloca.s   V_4
  IL_0041:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0046:  stloc.s    V_5
  IL_0048:  ldloca.s   V_4
  IL_004a:  call       ""readonly bool int?.HasValue.get""
  IL_004f:  brtrue.s   IL_0072
  IL_0051:  ldarga.s   V_0
  IL_0053:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0058:  stloc.s    V_5
  IL_005a:  ldloc.0
  IL_005b:  ldloc.3
  IL_005c:  ldloca.s   V_7
  IL_005e:  ldloc.s    V_5
  IL_0060:  call       ""int?..ctor(int)""
  IL_0065:  ldloc.s    V_7
  IL_0067:  constrained. ""T""
  IL_006d:  callvirt   ""void IMoveable.this[int].set""
  IL_0072:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_Value()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^1] ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^1] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '-1'
Position Length for item '2'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       81 (0x51)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldloc.0
  IL_0004:  constrained. ""T""
  IL_000a:  callvirt   ""int IMoveable.Length.get""
  IL_000f:  ldc.i4.1
  IL_0010:  sub
  IL_0011:  stloc.1
  IL_0012:  ldloc.0
  IL_0013:  ldloc.1
  IL_0014:  constrained. ""T""
  IL_001a:  callvirt   ""int? IMoveable.this[int].get""
  IL_001f:  stloc.2
  IL_0020:  ldloca.s   V_2
  IL_0022:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0027:  stloc.3
  IL_0028:  ldloca.s   V_2
  IL_002a:  call       ""readonly bool int?.HasValue.get""
  IL_002f:  brtrue.s   IL_0050
  IL_0031:  ldarga.s   V_0
  IL_0033:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0038:  stloc.3
  IL_0039:  ldloc.0
  IL_003a:  ldloc.1
  IL_003b:  ldloca.s   V_4
  IL_003d:  ldloc.3
  IL_003e:  call       ""int?..ctor(int)""
  IL_0043:  ldloc.s    V_4
  IL_0045:  constrained. ""T""
  IL_004b:  callvirt   ""void IMoveable.this[int].set""
  IL_0050:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_Value_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[^1] ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^1] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       81 (0x51)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldloc.0
  IL_0008:  box        ""T""
  IL_000d:  callvirt   ""int IMoveable.Length.get""
  IL_0012:  ldc.i4.1
  IL_0013:  sub
  IL_0014:  stloc.1
  IL_0015:  ldloc.0
  IL_0016:  box        ""T""
  IL_001b:  ldloc.1
  IL_001c:  callvirt   ""int? IMoveable.this[int].get""
  IL_0021:  stloc.2
  IL_0022:  ldloca.s   V_2
  IL_0024:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0029:  stloc.3
  IL_002a:  ldloca.s   V_2
  IL_002c:  call       ""readonly bool int?.HasValue.get""
  IL_0031:  brtrue.s   IL_0050
  IL_0033:  ldarg.0
  IL_0034:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0039:  stloc.3
  IL_003a:  ldloc.0
  IL_003b:  box        ""T""
  IL_0040:  ldloc.1
  IL_0041:  ldloca.s   V_4
  IL_0043:  ldloc.3
  IL_0044:  call       ""int?..ctor(int)""
  IL_0049:  ldloc.s    V_4
  IL_004b:  callvirt   ""void IMoveable.this[int].set""
  IL_0050:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      113 (0x71)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int? V_4,
                int V_5,
                T V_6,
                int? V_7)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_6
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_6
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldloc.0
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""int IMoveable.Length.get""
  IL_002c:  ldc.i4.1
  IL_002d:  sub
  IL_002e:  stloc.3
  IL_002f:  ldloc.0
  IL_0030:  ldloc.3
  IL_0031:  constrained. ""T""
  IL_0037:  callvirt   ""int? IMoveable.this[int].get""
  IL_003c:  stloc.s    V_4
  IL_003e:  ldloca.s   V_4
  IL_0040:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0045:  stloc.s    V_5
  IL_0047:  ldloca.s   V_4
  IL_0049:  call       ""readonly bool int?.HasValue.get""
  IL_004e:  brtrue.s   IL_0070
  IL_0050:  ldarg.0
  IL_0051:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0056:  stloc.s    V_5
  IL_0058:  ldloc.0
  IL_0059:  ldloc.3
  IL_005a:  ldloca.s   V_7
  IL_005c:  ldloc.s    V_5
  IL_005e:  call       ""int?..ctor(int)""
  IL_0063:  ldloc.s    V_7
  IL_0065:  constrained. ""T""
  IL_006b:  callvirt   ""void IMoveable.this[int].set""
  IL_0070:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_Value_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[^1] ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^1] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '-1'
Position Length for item '2'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       79 (0x4f)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int? V_2,
                int V_3,
                int? V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldloc.0
  IL_0003:  constrained. ""T""
  IL_0009:  callvirt   ""int IMoveable.Length.get""
  IL_000e:  ldc.i4.1
  IL_000f:  sub
  IL_0010:  stloc.1
  IL_0011:  ldloc.0
  IL_0012:  ldloc.1
  IL_0013:  constrained. ""T""
  IL_0019:  callvirt   ""int? IMoveable.this[int].get""
  IL_001e:  stloc.2
  IL_001f:  ldloca.s   V_2
  IL_0021:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0026:  stloc.3
  IL_0027:  ldloca.s   V_2
  IL_0029:  call       ""readonly bool int?.HasValue.get""
  IL_002e:  brtrue.s   IL_004e
  IL_0030:  ldarg.0
  IL_0031:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0036:  stloc.3
  IL_0037:  ldloc.0
  IL_0038:  ldloc.1
  IL_0039:  ldloca.s   V_4
  IL_003b:  ldloc.3
  IL_003c:  call       ""int?..ctor(int)""
  IL_0041:  ldloc.s    V_4
  IL_0043:  constrained. ""T""
  IL_0049:  callvirt   ""void IMoveable.this[int].set""
  IL_004e:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_Value_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^1] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^1] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      281 (0x119)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                int? V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_009b
    IL_000d:  ldarg.0
    IL_000e:  ldarg.0
    IL_000f:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0014:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0019:  ldarg.0
    IL_001a:  ldarg.0
    IL_001b:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0020:  box        ""T""
    IL_0025:  callvirt   ""int IMoveable.Length.get""
    IL_002a:  ldc.i4.1
    IL_002b:  sub
    IL_002c:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0031:  ldarg.0
    IL_0032:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0037:  box        ""T""
    IL_003c:  ldarg.0
    IL_003d:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0042:  callvirt   ""int? IMoveable.this[int].get""
    IL_0047:  stloc.1
    IL_0048:  ldloca.s   V_1
    IL_004a:  call       ""readonly int int?.GetValueOrDefault()""
    IL_004f:  stloc.2
    IL_0050:  ldloca.s   V_1
    IL_0052:  call       ""readonly bool int?.HasValue.get""
    IL_0057:  brtrue     IL_00de
    IL_005c:  ldarg.0
    IL_005d:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0062:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0067:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_006c:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0071:  stloc.3
    IL_0072:  ldloca.s   V_3
    IL_0074:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0079:  brtrue.s   IL_00b7
    IL_007b:  ldarg.0
    IL_007c:  ldc.i4.0
    IL_007d:  dup
    IL_007e:  stloc.0
    IL_007f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0084:  ldarg.0
    IL_0085:  ldloc.3
    IL_0086:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0091:  ldloca.s   V_3
    IL_0093:  ldarg.0
    IL_0094:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0099:  leave.s    IL_0118
    IL_009b:  ldarg.0
    IL_009c:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00a1:  stloc.3
    IL_00a2:  ldarg.0
    IL_00a3:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00a8:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00ae:  ldarg.0
    IL_00af:  ldc.i4.m1
    IL_00b0:  dup
    IL_00b1:  stloc.0
    IL_00b2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b7:  ldloca.s   V_3
    IL_00b9:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00be:  stloc.2
    IL_00bf:  ldarg.0
    IL_00c0:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00c5:  box        ""T""
    IL_00ca:  ldarg.0
    IL_00cb:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00d0:  ldloc.2
    IL_00d1:  newobj     ""int?..ctor(int)""
    IL_00d6:  dup
    IL_00d7:  stloc.s    V_4
    IL_00d9:  callvirt   ""void IMoveable.this[int].set""
    IL_00de:  ldarg.0
    IL_00df:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00e4:  initobj    ""T""
    IL_00ea:  leave.s    IL_0105
  }
  catch System.Exception
  {
    IL_00ec:  stloc.s    V_5
    IL_00ee:  ldarg.0
    IL_00ef:  ldc.i4.s   -2
    IL_00f1:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00f6:  ldarg.0
    IL_00f7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00fc:  ldloc.s    V_5
    IL_00fe:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0103:  leave.s    IL_0118
  }
  IL_0105:  ldarg.0
  IL_0106:  ldc.i4.s   -2
  IL_0108:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_010d:  ldarg.0
  IL_010e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0113:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0118:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      378 (0x17a)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00e2
    IL_000d:  ldloca.s   V_3
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.3
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldarg.0
    IL_002a:  ldloca.s   V_3
    IL_002c:  initobj    ""T""
    IL_0032:  ldloc.3
    IL_0033:  box        ""T""
    IL_0038:  brtrue.s   IL_0042
    IL_003a:  ldarg.0
    IL_003b:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0040:  br.s       IL_0048
    IL_0042:  ldarg.0
    IL_0043:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0048:  constrained. ""T""
    IL_004e:  callvirt   ""int IMoveable.Length.get""
    IL_0053:  ldc.i4.1
    IL_0054:  sub
    IL_0055:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_005a:  ldloca.s   V_3
    IL_005c:  initobj    ""T""
    IL_0062:  ldloc.3
    IL_0063:  box        ""T""
    IL_0068:  brtrue.s   IL_0072
    IL_006a:  ldarg.0
    IL_006b:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0070:  br.s       IL_0078
    IL_0072:  ldarg.0
    IL_0073:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0078:  ldarg.0
    IL_0079:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_007e:  constrained. ""T""
    IL_0084:  callvirt   ""int? IMoveable.this[int].get""
    IL_0089:  stloc.1
    IL_008a:  ldloca.s   V_1
    IL_008c:  call       ""readonly int int?.GetValueOrDefault()""
    IL_0091:  stloc.2
    IL_0092:  ldloca.s   V_1
    IL_0094:  call       ""readonly bool int?.HasValue.get""
    IL_0099:  brtrue     IL_013f
    IL_009e:  ldarg.0
    IL_009f:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00a4:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00a9:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00ae:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00b3:  stloc.s    V_4
    IL_00b5:  ldloca.s   V_4
    IL_00b7:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00bc:  brtrue.s   IL_00ff
    IL_00be:  ldarg.0
    IL_00bf:  ldc.i4.0
    IL_00c0:  dup
    IL_00c1:  stloc.0
    IL_00c2:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00c7:  ldarg.0
    IL_00c8:  ldloc.s    V_4
    IL_00ca:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00cf:  ldarg.0
    IL_00d0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00d5:  ldloca.s   V_4
    IL_00d7:  ldarg.0
    IL_00d8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00dd:  leave      IL_0179
    IL_00e2:  ldarg.0
    IL_00e3:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00e8:  stloc.s    V_4
    IL_00ea:  ldarg.0
    IL_00eb:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00f0:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00f6:  ldarg.0
    IL_00f7:  ldc.i4.m1
    IL_00f8:  dup
    IL_00f9:  stloc.0
    IL_00fa:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00ff:  ldloca.s   V_4
    IL_0101:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0106:  stloc.2
    IL_0107:  ldloca.s   V_3
    IL_0109:  initobj    ""T""
    IL_010f:  ldloc.3
    IL_0110:  box        ""T""
    IL_0115:  brtrue.s   IL_011f
    IL_0117:  ldarg.0
    IL_0118:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_011d:  br.s       IL_0125
    IL_011f:  ldarg.0
    IL_0120:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0125:  ldarg.0
    IL_0126:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_012b:  ldloc.2
    IL_012c:  newobj     ""int?..ctor(int)""
    IL_0131:  dup
    IL_0132:  stloc.s    V_5
    IL_0134:  constrained. ""T""
    IL_013a:  callvirt   ""void IMoveable.this[int].set""
    IL_013f:  ldarg.0
    IL_0140:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0145:  initobj    ""T""
    IL_014b:  leave.s    IL_0166
  }
  catch System.Exception
  {
    IL_014d:  stloc.s    V_6
    IL_014f:  ldarg.0
    IL_0150:  ldc.i4.s   -2
    IL_0152:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0157:  ldarg.0
    IL_0158:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_015d:  ldloc.s    V_6
    IL_015f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0164:  leave.s    IL_0179
  }
  IL_0166:  ldarg.0
  IL_0167:  ldc.i4.s   -2
  IL_0169:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_016e:  ldarg.0
  IL_016f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0174:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0179:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_Value_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^1] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^1] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '-1'
Position Length for item '2'
Position get for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
 // Code size      260 (0x104)
  .maxstack  4
  .locals init (int V_0,
                int? V_1,
                int V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                int? V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_0091
    IL_000d:  ldarg.0
    IL_000e:  ldarg.0
    IL_000f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0014:  constrained. ""T""
    IL_001a:  callvirt   ""int IMoveable.Length.get""
    IL_001f:  ldc.i4.1
    IL_0020:  sub
    IL_0021:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_002c:  ldarg.0
    IL_002d:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0032:  constrained. ""T""
    IL_0038:  callvirt   ""int? IMoveable.this[int].get""
    IL_003d:  stloc.1
    IL_003e:  ldloca.s   V_1
    IL_0040:  call       ""readonly int int?.GetValueOrDefault()""
    IL_0045:  stloc.2
    IL_0046:  ldloca.s   V_1
    IL_0048:  call       ""readonly bool int?.HasValue.get""
    IL_004d:  brtrue     IL_00d5
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0058:  call       ""int Program.GetOffset<T>(ref T)""
    IL_005d:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0062:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0067:  stloc.3
    IL_0068:  ldloca.s   V_3
    IL_006a:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_006f:  brtrue.s   IL_00ad
    IL_0071:  ldarg.0
    IL_0072:  ldc.i4.0
    IL_0073:  dup
    IL_0074:  stloc.0
    IL_0075:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007a:  ldarg.0
    IL_007b:  ldloc.3
    IL_007c:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0081:  ldarg.0
    IL_0082:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0087:  ldloca.s   V_3
    IL_0089:  ldarg.0
    IL_008a:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_008f:  leave.s    IL_0103
    IL_0091:  ldarg.0
    IL_0092:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0097:  stloc.3
    IL_0098:  ldarg.0
    IL_0099:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_009e:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00a4:  ldarg.0
    IL_00a5:  ldc.i4.m1
    IL_00a6:  dup
    IL_00a7:  stloc.0
    IL_00a8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00ad:  ldloca.s   V_3
    IL_00af:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00b4:  stloc.2
    IL_00b5:  ldarg.0
    IL_00b6:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00bb:  ldarg.0
    IL_00bc:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00c1:  ldloc.2
    IL_00c2:  newobj     ""int?..ctor(int)""
    IL_00c7:  dup
    IL_00c8:  stloc.s    V_4
    IL_00ca:  constrained. ""T""
    IL_00d0:  callvirt   ""void IMoveable.this[int].set""
    IL_00d5:  leave.s    IL_00f0
  }
  catch System.Exception
  {
    IL_00d7:  stloc.s    V_5
    IL_00d9:  ldarg.0
    IL_00da:  ldc.i4.s   -2
    IL_00dc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e1:  ldarg.0
    IL_00e2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e7:  ldloc.s    V_5
    IL_00e9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ee:  leave.s    IL_0103
  }
  IL_00f0:  ldarg.0
  IL_00f1:  ldc.i4.s   -2
  IL_00f3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00f8:  ldarg.0
  IL_00f9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00fe:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0103:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_IndexAndValue()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       88 (0x58)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.1
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  callvirt   ""int IMoveable.Length.get""
  IL_0015:  ldloc.1
  IL_0016:  sub
  IL_0017:  stloc.2
  IL_0018:  ldloc.0
  IL_0019:  box        ""T""
  IL_001e:  ldloc.2
  IL_001f:  callvirt   ""int? IMoveable.this[int].get""
  IL_0024:  stloc.3
  IL_0025:  ldloca.s   V_3
  IL_0027:  call       ""readonly int int?.GetValueOrDefault()""
  IL_002c:  stloc.s    V_4
  IL_002e:  ldloca.s   V_3
  IL_0030:  call       ""readonly bool int?.HasValue.get""
  IL_0035:  brtrue.s   IL_0057
  IL_0037:  ldarga.s   V_0
  IL_0039:  call       ""int Program.GetOffset<T>(ref T)""
  IL_003e:  stloc.s    V_4
  IL_0040:  ldloc.0
  IL_0041:  box        ""T""
  IL_0046:  ldloc.2
  IL_0047:  ldloca.s   V_5
  IL_0049:  ldloc.s    V_4
  IL_004b:  call       ""int?..ctor(int)""
  IL_0050:  ldloc.s    V_5
  IL_0052:  callvirt   ""void IMoveable.this[int].set""
  IL_0057:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      126 (0x7e)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int V_4,
                int? V_5,
                int V_6,
                T V_7,
                int? V_8)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_7
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_7
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  constrained. ""T""
  IL_0030:  callvirt   ""int IMoveable.Length.get""
  IL_0035:  ldloc.3
  IL_0036:  sub
  IL_0037:  stloc.s    V_4
  IL_0039:  ldloc.0
  IL_003a:  ldloc.s    V_4
  IL_003c:  constrained. ""T""
  IL_0042:  callvirt   ""int? IMoveable.this[int].get""
  IL_0047:  stloc.s    V_5
  IL_0049:  ldloca.s   V_5
  IL_004b:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0050:  stloc.s    V_6
  IL_0052:  ldloca.s   V_5
  IL_0054:  call       ""readonly bool int?.HasValue.get""
  IL_0059:  brtrue.s   IL_007d
  IL_005b:  ldarga.s   V_0
  IL_005d:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0062:  stloc.s    V_6
  IL_0064:  ldloc.0
  IL_0065:  ldloc.s    V_4
  IL_0067:  ldloca.s   V_8
  IL_0069:  ldloc.s    V_6
  IL_006b:  call       ""int?..ctor(int)""
  IL_0070:  ldloc.s    V_8
  IL_0072:  constrained. ""T""
  IL_0078:  callvirt   ""void IMoveable.this[int].set""
  IL_007d:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_IndexAndValue()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] ??= GetOffset(ref item);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       92 (0x5c)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int IMoveable.Length.get""
  IL_0017:  ldloc.1
  IL_0018:  sub
  IL_0019:  stloc.2
  IL_001a:  ldloc.0
  IL_001b:  ldloc.2
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""int? IMoveable.this[int].get""
  IL_0027:  stloc.3
  IL_0028:  ldloca.s   V_3
  IL_002a:  call       ""readonly int int?.GetValueOrDefault()""
  IL_002f:  stloc.s    V_4
  IL_0031:  ldloca.s   V_3
  IL_0033:  call       ""readonly bool int?.HasValue.get""
  IL_0038:  brtrue.s   IL_005b
  IL_003a:  ldarga.s   V_0
  IL_003c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0041:  stloc.s    V_4
  IL_0043:  ldloc.0
  IL_0044:  ldloc.2
  IL_0045:  ldloca.s   V_5
  IL_0047:  ldloc.s    V_4
  IL_0049:  call       ""int?..ctor(int)""
  IL_004e:  ldloc.s    V_5
  IL_0050:  constrained. ""T""
  IL_0056:  callvirt   ""void IMoveable.this[int].set""
  IL_005b:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_IndexAndValue_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       91 (0x5b)
  .maxstack  4
  .locals init (T V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldarg.0
  IL_0008:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000d:  stloc.1
  IL_000e:  ldloc.0
  IL_000f:  box        ""T""
  IL_0014:  callvirt   ""int IMoveable.Length.get""
  IL_0019:  ldloc.1
  IL_001a:  sub
  IL_001b:  stloc.2
  IL_001c:  ldloc.0
  IL_001d:  box        ""T""
  IL_0022:  ldloc.2
  IL_0023:  callvirt   ""int? IMoveable.this[int].get""
  IL_0028:  stloc.3
  IL_0029:  ldloca.s   V_3
  IL_002b:  call       ""readonly int int?.GetValueOrDefault()""
  IL_0030:  stloc.s    V_4
  IL_0032:  ldloca.s   V_3
  IL_0034:  call       ""readonly bool int?.HasValue.get""
  IL_0039:  brtrue.s   IL_005a
  IL_003b:  ldarg.0
  IL_003c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0041:  stloc.s    V_4
  IL_0043:  ldloc.0
  IL_0044:  box        ""T""
  IL_0049:  ldloc.2
  IL_004a:  ldloca.s   V_5
  IL_004c:  ldloc.s    V_4
  IL_004e:  call       ""int?..ctor(int)""
  IL_0053:  ldloc.s    V_5
  IL_0055:  callvirt   ""void IMoveable.this[int].set""
  IL_005a:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      123 (0x7b)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                int V_4,
                int? V_5,
                int V_6,
                T V_7,
                int? V_8)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_7
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_7
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  constrained. ""T""
  IL_002e:  callvirt   ""int IMoveable.Length.get""
  IL_0033:  ldloc.3
  IL_0034:  sub
  IL_0035:  stloc.s    V_4
  IL_0037:  ldloc.0
  IL_0038:  ldloc.s    V_4
  IL_003a:  constrained. ""T""
  IL_0040:  callvirt   ""int? IMoveable.this[int].get""
  IL_0045:  stloc.s    V_5
  IL_0047:  ldloca.s   V_5
  IL_0049:  call       ""readonly int int?.GetValueOrDefault()""
  IL_004e:  stloc.s    V_6
  IL_0050:  ldloca.s   V_5
  IL_0052:  call       ""readonly bool int?.HasValue.get""
  IL_0057:  brtrue.s   IL_007a
  IL_0059:  ldarg.0
  IL_005a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_005f:  stloc.s    V_6
  IL_0061:  ldloc.0
  IL_0062:  ldloc.s    V_4
  IL_0064:  ldloca.s   V_8
  IL_0066:  ldloc.s    V_6
  IL_0068:  call       ""int?..ctor(int)""
  IL_006d:  ldloc.s    V_8
  IL_006f:  constrained. ""T""
  IL_0075:  callvirt   ""void IMoveable.this[int].set""
  IL_007a:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_IndexAndValue_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] ??= GetOffset(ref item);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       89 (0x59)
  .maxstack  4
  .locals init (T& V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                int? V_5)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  constrained. ""T""
  IL_0010:  callvirt   ""int IMoveable.Length.get""
  IL_0015:  ldloc.1
  IL_0016:  sub
  IL_0017:  stloc.2
  IL_0018:  ldloc.0
  IL_0019:  ldloc.2
  IL_001a:  constrained. ""T""
  IL_0020:  callvirt   ""int? IMoveable.this[int].get""
  IL_0025:  stloc.3
  IL_0026:  ldloca.s   V_3
  IL_0028:  call       ""readonly int int?.GetValueOrDefault()""
  IL_002d:  stloc.s    V_4
  IL_002f:  ldloca.s   V_3
  IL_0031:  call       ""readonly bool int?.HasValue.get""
  IL_0036:  brtrue.s   IL_0058
  IL_0038:  ldarg.0
  IL_0039:  call       ""int Program.GetOffset<T>(ref T)""
  IL_003e:  stloc.s    V_4
  IL_0040:  ldloc.0
  IL_0041:  ldloc.2
  IL_0042:  ldloca.s   V_5
  IL_0044:  ldloc.s    V_4
  IL_0046:  call       ""int?..ctor(int)""
  IL_004b:  ldloc.s    V_5
  IL_004d:  constrained. ""T""
  IL_0053:  callvirt   ""void IMoveable.this[int].set""
  IL_0058:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_IndexAndValue_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^GetOffset(ref item)] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      296 (0x128)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00a9
    IL_000d:  ldarg.0
    IL_000e:  ldarg.0
    IL_000f:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0014:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0019:  ldarg.0
    IL_001a:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001f:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0024:  stloc.1
    IL_0025:  ldarg.0
    IL_0026:  ldarg.0
    IL_0027:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_002c:  box        ""T""
    IL_0031:  callvirt   ""int IMoveable.Length.get""
    IL_0036:  ldloc.1
    IL_0037:  sub
    IL_0038:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_003d:  ldarg.0
    IL_003e:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0043:  box        ""T""
    IL_0048:  ldarg.0
    IL_0049:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_004e:  callvirt   ""int? IMoveable.this[int].get""
    IL_0053:  stloc.2
    IL_0054:  ldloca.s   V_2
    IL_0056:  call       ""readonly int int?.GetValueOrDefault()""
    IL_005b:  stloc.3
    IL_005c:  ldloca.s   V_2
    IL_005e:  call       ""readonly bool int?.HasValue.get""
    IL_0063:  brtrue     IL_00ed
    IL_0068:  ldarg.0
    IL_0069:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_006e:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0073:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0078:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_007d:  stloc.s    V_4
    IL_007f:  ldloca.s   V_4
    IL_0081:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0086:  brtrue.s   IL_00c6
    IL_0088:  ldarg.0
    IL_0089:  ldc.i4.0
    IL_008a:  dup
    IL_008b:  stloc.0
    IL_008c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0091:  ldarg.0
    IL_0092:  ldloc.s    V_4
    IL_0094:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0099:  ldarg.0
    IL_009a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_009f:  ldloca.s   V_4
    IL_00a1:  ldarg.0
    IL_00a2:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00a7:  leave.s    IL_0127
    IL_00a9:  ldarg.0
    IL_00aa:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00af:  stloc.s    V_4
    IL_00b1:  ldarg.0
    IL_00b2:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00b7:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00bd:  ldarg.0
    IL_00be:  ldc.i4.m1
    IL_00bf:  dup
    IL_00c0:  stloc.0
    IL_00c1:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c6:  ldloca.s   V_4
    IL_00c8:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00cd:  stloc.3
    IL_00ce:  ldarg.0
    IL_00cf:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00d4:  box        ""T""
    IL_00d9:  ldarg.0
    IL_00da:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00df:  ldloc.3
    IL_00e0:  newobj     ""int?..ctor(int)""
    IL_00e5:  dup
    IL_00e6:  stloc.s    V_5
    IL_00e8:  callvirt   ""void IMoveable.this[int].set""
    IL_00ed:  ldarg.0
    IL_00ee:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00f3:  initobj    ""T""
    IL_00f9:  leave.s    IL_0114
  }
  catch System.Exception
  {
    IL_00fb:  stloc.s    V_6
    IL_00fd:  ldarg.0
    IL_00fe:  ldc.i4.s   -2
    IL_0100:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0105:  ldarg.0
    IL_0106:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_010b:  ldloc.s    V_6
    IL_010d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0112:  leave.s    IL_0127
  }
  IL_0114:  ldarg.0
  IL_0115:  ldc.i4.s   -2
  IL_0117:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_011c:  ldarg.0
  IL_011d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0122:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0127:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      394 (0x18a)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_00f1
    IL_000d:  ldloca.s   V_4
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.s    V_4
    IL_0017:  box        ""T""
    IL_001c:  brtrue.s   IL_002a
    IL_001e:  ldarg.0
    IL_001f:  ldarg.0
    IL_0020:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0025:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_002a:  ldarg.0
    IL_002b:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0030:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0035:  stloc.1
    IL_0036:  ldarg.0
    IL_0037:  ldloca.s   V_4
    IL_0039:  initobj    ""T""
    IL_003f:  ldloc.s    V_4
    IL_0041:  box        ""T""
    IL_0046:  brtrue.s   IL_0050
    IL_0048:  ldarg.0
    IL_0049:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_004e:  br.s       IL_0056
    IL_0050:  ldarg.0
    IL_0051:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0056:  constrained. ""T""
    IL_005c:  callvirt   ""int IMoveable.Length.get""
    IL_0061:  ldloc.1
    IL_0062:  sub
    IL_0063:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_0068:  ldloca.s   V_4
    IL_006a:  initobj    ""T""
    IL_0070:  ldloc.s    V_4
    IL_0072:  box        ""T""
    IL_0077:  brtrue.s   IL_0081
    IL_0079:  ldarg.0
    IL_007a:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_007f:  br.s       IL_0087
    IL_0081:  ldarg.0
    IL_0082:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0087:  ldarg.0
    IL_0088:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_008d:  constrained. ""T""
    IL_0093:  callvirt   ""int? IMoveable.this[int].get""
    IL_0098:  stloc.2
    IL_0099:  ldloca.s   V_2
    IL_009b:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00a0:  stloc.3
    IL_00a1:  ldloca.s   V_2
    IL_00a3:  call       ""readonly bool int?.HasValue.get""
    IL_00a8:  brtrue     IL_014f
    IL_00ad:  ldarg.0
    IL_00ae:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00b3:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00b8:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00bd:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00c2:  stloc.s    V_5
    IL_00c4:  ldloca.s   V_5
    IL_00c6:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00cb:  brtrue.s   IL_010e
    IL_00cd:  ldarg.0
    IL_00ce:  ldc.i4.0
    IL_00cf:  dup
    IL_00d0:  stloc.0
    IL_00d1:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00d6:  ldarg.0
    IL_00d7:  ldloc.s    V_5
    IL_00d9:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00de:  ldarg.0
    IL_00df:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_00e4:  ldloca.s   V_5
    IL_00e6:  ldarg.0
    IL_00e7:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_00ec:  leave      IL_0189
    IL_00f1:  ldarg.0
    IL_00f2:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00f7:  stloc.s    V_5
    IL_00f9:  ldarg.0
    IL_00fa:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00ff:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0105:  ldarg.0
    IL_0106:  ldc.i4.m1
    IL_0107:  dup
    IL_0108:  stloc.0
    IL_0109:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_010e:  ldloca.s   V_5
    IL_0110:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0115:  stloc.3
    IL_0116:  ldloca.s   V_4
    IL_0118:  initobj    ""T""
    IL_011e:  ldloc.s    V_4
    IL_0120:  box        ""T""
    IL_0125:  brtrue.s   IL_012f
    IL_0127:  ldarg.0
    IL_0128:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_012d:  br.s       IL_0135
    IL_012f:  ldarg.0
    IL_0130:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0135:  ldarg.0
    IL_0136:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_013b:  ldloc.3
    IL_013c:  newobj     ""int?..ctor(int)""
    IL_0141:  dup
    IL_0142:  stloc.s    V_6
    IL_0144:  constrained. ""T""
    IL_014a:  callvirt   ""void IMoveable.this[int].set""
    IL_014f:  ldarg.0
    IL_0150:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0155:  initobj    ""T""
    IL_015b:  leave.s    IL_0176
  }
  catch System.Exception
  {
    IL_015d:  stloc.s    V_7
    IL_015f:  ldarg.0
    IL_0160:  ldc.i4.s   -2
    IL_0162:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0167:  ldarg.0
    IL_0168:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_016d:  ldloc.s    V_7
    IL_016f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0174:  leave.s    IL_0189
  }
  IL_0176:  ldarg.0
  IL_0177:  ldc.i4.s   -2
  IL_0179:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_017e:  ldarg.0
  IL_017f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0184:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0189:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_IndexAndValue_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^GetOffset(ref item)] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^GetOffset(ref item)] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      275 (0x113)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_009f
    IL_000d:  ldarg.0
    IL_000e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0013:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0018:  stloc.1
    IL_0019:  ldarg.0
    IL_001a:  ldarg.0
    IL_001b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0020:  constrained. ""T""
    IL_0026:  callvirt   ""int IMoveable.Length.get""
    IL_002b:  ldloc.1
    IL_002c:  sub
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0032:  ldarg.0
    IL_0033:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0038:  ldarg.0
    IL_0039:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_003e:  constrained. ""T""
    IL_0044:  callvirt   ""int? IMoveable.this[int].get""
    IL_0049:  stloc.2
    IL_004a:  ldloca.s   V_2
    IL_004c:  call       ""readonly int int?.GetValueOrDefault()""
    IL_0051:  stloc.3
    IL_0052:  ldloca.s   V_2
    IL_0054:  call       ""readonly bool int?.HasValue.get""
    IL_0059:  brtrue     IL_00e4
    IL_005e:  ldarg.0
    IL_005f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0064:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0069:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_006e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0073:  stloc.s    V_4
    IL_0075:  ldloca.s   V_4
    IL_0077:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_007c:  brtrue.s   IL_00bc
    IL_007e:  ldarg.0
    IL_007f:  ldc.i4.0
    IL_0080:  dup
    IL_0081:  stloc.0
    IL_0082:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0087:  ldarg.0
    IL_0088:  ldloc.s    V_4
    IL_008a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_008f:  ldarg.0
    IL_0090:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0095:  ldloca.s   V_4
    IL_0097:  ldarg.0
    IL_0098:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_009d:  leave.s    IL_0112
    IL_009f:  ldarg.0
    IL_00a0:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00a5:  stloc.s    V_4
    IL_00a7:  ldarg.0
    IL_00a8:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00ad:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00b3:  ldarg.0
    IL_00b4:  ldc.i4.m1
    IL_00b5:  dup
    IL_00b6:  stloc.0
    IL_00b7:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00bc:  ldloca.s   V_4
    IL_00be:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00c3:  stloc.3
    IL_00c4:  ldarg.0
    IL_00c5:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00ca:  ldarg.0
    IL_00cb:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00d0:  ldloc.3
    IL_00d1:  newobj     ""int?..ctor(int)""
    IL_00d6:  dup
    IL_00d7:  stloc.s    V_5
    IL_00d9:  constrained. ""T""
    IL_00df:  callvirt   ""void IMoveable.this[int].set""
    IL_00e4:  leave.s    IL_00ff
  }
  catch System.Exception
  {
    IL_00e6:  stloc.s    V_6
    IL_00e8:  ldarg.0
    IL_00e9:  ldc.i4.s   -2
    IL_00eb:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00f0:  ldarg.0
    IL_00f1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00f6:  ldloc.s    V_6
    IL_00f8:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00fd:  leave.s    IL_0112
  }
  IL_00ff:  ldarg.0
  IL_0100:  ldc.i4.s   -2
  IL_0102:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0107:  ldarg.0
  IL_0108:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_010d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0112:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_IndexAndValue_Async_03()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= GetOffset(ref item);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      281 (0x119)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_005a
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.s    V_5
    IL_002d:  ldloca.s   V_5
    IL_002f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0034:  brtrue.s   IL_0077
    IL_0036:  ldarg.0
    IL_0037:  ldc.i4.0
    IL_0038:  dup
    IL_0039:  stloc.0
    IL_003a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003f:  ldarg.0
    IL_0040:  ldloc.s    V_5
    IL_0042:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0047:  ldarg.0
    IL_0048:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004d:  ldloca.s   V_5
    IL_004f:  ldarg.0
    IL_0050:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0055:  leave      IL_0118
    IL_005a:  ldarg.0
    IL_005b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0060:  stloc.s    V_5
    IL_0062:  ldarg.0
    IL_0063:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006e:  ldarg.0
    IL_006f:  ldc.i4.m1
    IL_0070:  dup
    IL_0071:  stloc.0
    IL_0072:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0077:  ldloca.s   V_5
    IL_0079:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007e:  stloc.1
    IL_007f:  ldarg.0
    IL_0080:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0085:  box        ""T""
    IL_008a:  callvirt   ""int IMoveable.Length.get""
    IL_008f:  ldloc.1
    IL_0090:  sub
    IL_0091:  stloc.2
    IL_0092:  ldarg.0
    IL_0093:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0098:  box        ""T""
    IL_009d:  ldloc.2
    IL_009e:  callvirt   ""int? IMoveable.this[int].get""
    IL_00a3:  stloc.3
    IL_00a4:  ldloca.s   V_3
    IL_00a6:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00ab:  stloc.s    V_4
    IL_00ad:  ldloca.s   V_3
    IL_00af:  call       ""readonly bool int?.HasValue.get""
    IL_00b4:  brtrue.s   IL_00de
    IL_00b6:  ldarg.0
    IL_00b7:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00bc:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00c1:  stloc.s    V_4
    IL_00c3:  ldarg.0
    IL_00c4:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00c9:  box        ""T""
    IL_00ce:  ldloc.2
    IL_00cf:  ldloc.s    V_4
    IL_00d1:  newobj     ""int?..ctor(int)""
    IL_00d6:  dup
    IL_00d7:  stloc.s    V_6
    IL_00d9:  callvirt   ""void IMoveable.this[int].set""
    IL_00de:  ldarg.0
    IL_00df:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00e4:  initobj    ""T""
    IL_00ea:  leave.s    IL_0105
  }
  catch System.Exception
  {
    IL_00ec:  stloc.s    V_7
    IL_00ee:  ldarg.0
    IL_00ef:  ldc.i4.s   -2
    IL_00f1:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00f6:  ldarg.0
    IL_00f7:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00fc:  ldloc.s    V_7
    IL_00fe:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0103:  leave.s    IL_0118
  }
  IL_0105:  ldarg.0
  IL_0106:  ldc.i4.s   -2
  IL_0108:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_010d:  ldarg.0
  IL_010e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0113:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0118:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      376 (0x178)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                T V_5,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_6,
                int? V_7,
                System.Exception V_8)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006b
    IL_000a:  ldloca.s   V_5
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.s    V_5
    IL_0014:  box        ""T""
    IL_0019:  brtrue.s   IL_0027
    IL_001b:  ldarg.0
    IL_001c:  ldarg.0
    IL_001d:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0022:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0027:  ldarg.0
    IL_0028:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002d:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0032:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0037:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003c:  stloc.s    V_6
    IL_003e:  ldloca.s   V_6
    IL_0040:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0045:  brtrue.s   IL_0088
    IL_0047:  ldarg.0
    IL_0048:  ldc.i4.0
    IL_0049:  dup
    IL_004a:  stloc.0
    IL_004b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0050:  ldarg.0
    IL_0051:  ldloc.s    V_6
    IL_0053:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  ldarg.0
    IL_0059:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005e:  ldloca.s   V_6
    IL_0060:  ldarg.0
    IL_0061:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0066:  leave      IL_0177
    IL_006b:  ldarg.0
    IL_006c:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0071:  stloc.s    V_6
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0079:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007f:  ldarg.0
    IL_0080:  ldc.i4.m1
    IL_0081:  dup
    IL_0082:  stloc.0
    IL_0083:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0088:  ldloca.s   V_6
    IL_008a:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008f:  stloc.1
    IL_0090:  ldloca.s   V_5
    IL_0092:  initobj    ""T""
    IL_0098:  ldloc.s    V_5
    IL_009a:  box        ""T""
    IL_009f:  brtrue.s   IL_00a9
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a7:  br.s       IL_00af
    IL_00a9:  ldarg.0
    IL_00aa:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00af:  constrained. ""T""
    IL_00b5:  callvirt   ""int IMoveable.Length.get""
    IL_00ba:  ldloc.1
    IL_00bb:  sub
    IL_00bc:  stloc.2
    IL_00bd:  ldloca.s   V_5
    IL_00bf:  initobj    ""T""
    IL_00c5:  ldloc.s    V_5
    IL_00c7:  box        ""T""
    IL_00cc:  brtrue.s   IL_00d6
    IL_00ce:  ldarg.0
    IL_00cf:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00d4:  br.s       IL_00dc
    IL_00d6:  ldarg.0
    IL_00d7:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00dc:  ldloc.2
    IL_00dd:  constrained. ""T""
    IL_00e3:  callvirt   ""int? IMoveable.this[int].get""
    IL_00e8:  stloc.3
    IL_00e9:  ldloca.s   V_3
    IL_00eb:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00f0:  stloc.s    V_4
    IL_00f2:  ldloca.s   V_3
    IL_00f4:  call       ""readonly bool int?.HasValue.get""
    IL_00f9:  brtrue.s   IL_013d
    IL_00fb:  ldarg.0
    IL_00fc:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0101:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0106:  stloc.s    V_4
    IL_0108:  ldloca.s   V_5
    IL_010a:  initobj    ""T""
    IL_0110:  ldloc.s    V_5
    IL_0112:  box        ""T""
    IL_0117:  brtrue.s   IL_0121
    IL_0119:  ldarg.0
    IL_011a:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_011f:  br.s       IL_0127
    IL_0121:  ldarg.0
    IL_0122:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0127:  ldloc.2
    IL_0128:  ldloc.s    V_4
    IL_012a:  newobj     ""int?..ctor(int)""
    IL_012f:  dup
    IL_0130:  stloc.s    V_7
    IL_0132:  constrained. ""T""
    IL_0138:  callvirt   ""void IMoveable.this[int].set""
    IL_013d:  ldarg.0
    IL_013e:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0143:  initobj    ""T""
    IL_0149:  leave.s    IL_0164
  }
  catch System.Exception
  {
    IL_014b:  stloc.s    V_8
    IL_014d:  ldarg.0
    IL_014e:  ldc.i4.s   -2
    IL_0150:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0155:  ldarg.0
    IL_0156:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_015b:  ldloc.s    V_8
    IL_015d:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0162:  leave.s    IL_0177
  }
  IL_0164:  ldarg.0
  IL_0165:  ldc.i4.s   -2
  IL_0167:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_016c:  ldarg.0
  IL_016d:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0172:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0177:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_IndexAndValue_Async_03()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= GetOffset(ref item);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= GetOffset(ref item);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      260 (0x104)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int V_2,
                int? V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004e
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.s    V_5
    IL_0021:  ldloca.s   V_5
    IL_0023:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0028:  brtrue.s   IL_006b
    IL_002a:  ldarg.0
    IL_002b:  ldc.i4.0
    IL_002c:  dup
    IL_002d:  stloc.0
    IL_002e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0033:  ldarg.0
    IL_0034:  ldloc.s    V_5
    IL_0036:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_003b:  ldarg.0
    IL_003c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0041:  ldloca.s   V_5
    IL_0043:  ldarg.0
    IL_0044:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0049:  leave      IL_0103
    IL_004e:  ldarg.0
    IL_004f:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0054:  stloc.s    V_5
    IL_0056:  ldarg.0
    IL_0057:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0062:  ldarg.0
    IL_0063:  ldc.i4.m1
    IL_0064:  dup
    IL_0065:  stloc.0
    IL_0066:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_006b:  ldloca.s   V_5
    IL_006d:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0072:  stloc.1
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0079:  constrained. ""T""
    IL_007f:  callvirt   ""int IMoveable.Length.get""
    IL_0084:  ldloc.1
    IL_0085:  sub
    IL_0086:  stloc.2
    IL_0087:  ldarg.0
    IL_0088:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_008d:  ldloc.2
    IL_008e:  constrained. ""T""
    IL_0094:  callvirt   ""int? IMoveable.this[int].get""
    IL_0099:  stloc.3
    IL_009a:  ldloca.s   V_3
    IL_009c:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00a1:  stloc.s    V_4
    IL_00a3:  ldloca.s   V_3
    IL_00a5:  call       ""readonly bool int?.HasValue.get""
    IL_00aa:  brtrue.s   IL_00d5
    IL_00ac:  ldarg.0
    IL_00ad:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b2:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00b7:  stloc.s    V_4
    IL_00b9:  ldarg.0
    IL_00ba:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00bf:  ldloc.2
    IL_00c0:  ldloc.s    V_4
    IL_00c2:  newobj     ""int?..ctor(int)""
    IL_00c7:  dup
    IL_00c8:  stloc.s    V_6
    IL_00ca:  constrained. ""T""
    IL_00d0:  callvirt   ""void IMoveable.this[int].set""
    IL_00d5:  leave.s    IL_00f0
  }
  catch System.Exception
  {
    IL_00d7:  stloc.s    V_7
    IL_00d9:  ldarg.0
    IL_00da:  ldc.i4.s   -2
    IL_00dc:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e1:  ldarg.0
    IL_00e2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e7:  ldloc.s    V_7
    IL_00e9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00ee:  leave.s    IL_0103
  }
  IL_00f0:  ldarg.0
  IL_00f1:  ldc.i4.s   -2
  IL_00f3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00f8:  ldarg.0
  IL_00f9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00fe:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0103:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Class_IndexAndValue_Async_04()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position get for item '1'
Position set for item '1'
Position Length for item '2'
Position get for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      393 (0x189)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0061
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_010a
    IL_0011:  ldarg.0
    IL_0012:  ldarg.0
    IL_0013:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0018:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_001d:  ldarg.0
    IL_001e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0028:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_002d:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0032:  stloc.s    V_4
    IL_0034:  ldloca.s   V_4
    IL_0036:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_003b:  brtrue.s   IL_007e
    IL_003d:  ldarg.0
    IL_003e:  ldc.i4.0
    IL_003f:  dup
    IL_0040:  stloc.0
    IL_0041:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0046:  ldarg.0
    IL_0047:  ldloc.s    V_4
    IL_0049:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004e:  ldarg.0
    IL_004f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0054:  ldloca.s   V_4
    IL_0056:  ldarg.0
    IL_0057:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_005c:  leave      IL_0188
    IL_0061:  ldarg.0
    IL_0062:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0067:  stloc.s    V_4
    IL_0069:  ldarg.0
    IL_006a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0075:  ldarg.0
    IL_0076:  ldc.i4.m1
    IL_0077:  dup
    IL_0078:  stloc.0
    IL_0079:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007e:  ldloca.s   V_4
    IL_0080:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0085:  stloc.1
    IL_0086:  ldarg.0
    IL_0087:  ldarg.0
    IL_0088:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008d:  box        ""T""
    IL_0092:  callvirt   ""int IMoveable.Length.get""
    IL_0097:  ldloc.1
    IL_0098:  sub
    IL_0099:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_009e:  ldarg.0
    IL_009f:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a4:  box        ""T""
    IL_00a9:  ldarg.0
    IL_00aa:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00af:  callvirt   ""int? IMoveable.this[int].get""
    IL_00b4:  stloc.2
    IL_00b5:  ldloca.s   V_2
    IL_00b7:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00bc:  stloc.3
    IL_00bd:  ldloca.s   V_2
    IL_00bf:  call       ""readonly bool int?.HasValue.get""
    IL_00c4:  brtrue     IL_014e
    IL_00c9:  ldarg.0
    IL_00ca:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00cf:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00d4:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00d9:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00de:  stloc.s    V_4
    IL_00e0:  ldloca.s   V_4
    IL_00e2:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00e7:  brtrue.s   IL_0127
    IL_00e9:  ldarg.0
    IL_00ea:  ldc.i4.1
    IL_00eb:  dup
    IL_00ec:  stloc.0
    IL_00ed:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00f2:  ldarg.0
    IL_00f3:  ldloc.s    V_4
    IL_00f5:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00fa:  ldarg.0
    IL_00fb:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0100:  ldloca.s   V_4
    IL_0102:  ldarg.0
    IL_0103:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0108:  leave.s    IL_0188
    IL_010a:  ldarg.0
    IL_010b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0110:  stloc.s    V_4
    IL_0112:  ldarg.0
    IL_0113:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0118:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_011e:  ldarg.0
    IL_011f:  ldc.i4.m1
    IL_0120:  dup
    IL_0121:  stloc.0
    IL_0122:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0127:  ldloca.s   V_4
    IL_0129:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_012e:  stloc.3
    IL_012f:  ldarg.0
    IL_0130:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0135:  box        ""T""
    IL_013a:  ldarg.0
    IL_013b:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_0140:  ldloc.3
    IL_0141:  newobj     ""int?..ctor(int)""
    IL_0146:  dup
    IL_0147:  stloc.s    V_5
    IL_0149:  callvirt   ""void IMoveable.this[int].set""
    IL_014e:  ldarg.0
    IL_014f:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0154:  initobj    ""T""
    IL_015a:  leave.s    IL_0175
  }
  catch System.Exception
  {
    IL_015c:  stloc.s    V_6
    IL_015e:  ldarg.0
    IL_015f:  ldc.i4.s   -2
    IL_0161:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0166:  ldarg.0
    IL_0167:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_016c:  ldloc.s    V_6
    IL_016e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0173:  leave.s    IL_0188
  }
  IL_0175:  ldarg.0
  IL_0176:  ldc.i4.s   -2
  IL_0178:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_017d:  ldarg.0
  IL_017e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0183:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0188:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      491 (0x1eb)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                T V_4,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_5,
                int? V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0072
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_0152
    IL_0011:  ldloca.s   V_4
    IL_0013:  initobj    ""T""
    IL_0019:  ldloc.s    V_4
    IL_001b:  box        ""T""
    IL_0020:  brtrue.s   IL_002e
    IL_0022:  ldarg.0
    IL_0023:  ldarg.0
    IL_0024:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0029:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_002e:  ldarg.0
    IL_002f:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0034:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0039:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_003e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0043:  stloc.s    V_5
    IL_0045:  ldloca.s   V_5
    IL_0047:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_004c:  brtrue.s   IL_008f
    IL_004e:  ldarg.0
    IL_004f:  ldc.i4.0
    IL_0050:  dup
    IL_0051:  stloc.0
    IL_0052:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0057:  ldarg.0
    IL_0058:  ldloc.s    V_5
    IL_005a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0065:  ldloca.s   V_5
    IL_0067:  ldarg.0
    IL_0068:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_006d:  leave      IL_01ea
    IL_0072:  ldarg.0
    IL_0073:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0078:  stloc.s    V_5
    IL_007a:  ldarg.0
    IL_007b:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0080:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0086:  ldarg.0
    IL_0087:  ldc.i4.m1
    IL_0088:  dup
    IL_0089:  stloc.0
    IL_008a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_008f:  ldloca.s   V_5
    IL_0091:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0096:  stloc.1
    IL_0097:  ldarg.0
    IL_0098:  ldloca.s   V_4
    IL_009a:  initobj    ""T""
    IL_00a0:  ldloc.s    V_4
    IL_00a2:  box        ""T""
    IL_00a7:  brtrue.s   IL_00b1
    IL_00a9:  ldarg.0
    IL_00aa:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00af:  br.s       IL_00b7
    IL_00b1:  ldarg.0
    IL_00b2:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00b7:  constrained. ""T""
    IL_00bd:  callvirt   ""int IMoveable.Length.get""
    IL_00c2:  ldloc.1
    IL_00c3:  sub
    IL_00c4:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00c9:  ldloca.s   V_4
    IL_00cb:  initobj    ""T""
    IL_00d1:  ldloc.s    V_4
    IL_00d3:  box        ""T""
    IL_00d8:  brtrue.s   IL_00e2
    IL_00da:  ldarg.0
    IL_00db:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00e0:  br.s       IL_00e8
    IL_00e2:  ldarg.0
    IL_00e3:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00e8:  ldarg.0
    IL_00e9:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00ee:  constrained. ""T""
    IL_00f4:  callvirt   ""int? IMoveable.this[int].get""
    IL_00f9:  stloc.2
    IL_00fa:  ldloca.s   V_2
    IL_00fc:  call       ""readonly int int?.GetValueOrDefault()""
    IL_0101:  stloc.3
    IL_0102:  ldloca.s   V_2
    IL_0104:  call       ""readonly bool int?.HasValue.get""
    IL_0109:  brtrue     IL_01b0
    IL_010e:  ldarg.0
    IL_010f:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0114:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0119:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_011e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0123:  stloc.s    V_5
    IL_0125:  ldloca.s   V_5
    IL_0127:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_012c:  brtrue.s   IL_016f
    IL_012e:  ldarg.0
    IL_012f:  ldc.i4.1
    IL_0130:  dup
    IL_0131:  stloc.0
    IL_0132:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0137:  ldarg.0
    IL_0138:  ldloc.s    V_5
    IL_013a:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_013f:  ldarg.0
    IL_0140:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0145:  ldloca.s   V_5
    IL_0147:  ldarg.0
    IL_0148:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_014d:  leave      IL_01ea
    IL_0152:  ldarg.0
    IL_0153:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0158:  stloc.s    V_5
    IL_015a:  ldarg.0
    IL_015b:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0160:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0166:  ldarg.0
    IL_0167:  ldc.i4.m1
    IL_0168:  dup
    IL_0169:  stloc.0
    IL_016a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_016f:  ldloca.s   V_5
    IL_0171:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0176:  stloc.3
    IL_0177:  ldloca.s   V_4
    IL_0179:  initobj    ""T""
    IL_017f:  ldloc.s    V_4
    IL_0181:  box        ""T""
    IL_0186:  brtrue.s   IL_0190
    IL_0188:  ldarg.0
    IL_0189:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_018e:  br.s       IL_0196
    IL_0190:  ldarg.0
    IL_0191:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0196:  ldarg.0
    IL_0197:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_019c:  ldloc.3
    IL_019d:  newobj     ""int?..ctor(int)""
    IL_01a2:  dup
    IL_01a3:  stloc.s    V_6
    IL_01a5:  constrained. ""T""
    IL_01ab:  callvirt   ""void IMoveable.this[int].set""
    IL_01b0:  ldarg.0
    IL_01b1:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_01b6:  initobj    ""T""
    IL_01bc:  leave.s    IL_01d7
  }
  catch System.Exception
  {
    IL_01be:  stloc.s    V_7
    IL_01c0:  ldarg.0
    IL_01c1:  ldc.i4.s   -2
    IL_01c3:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_01c8:  ldarg.0
    IL_01c9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_01ce:  ldloc.s    V_7
    IL_01d0:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_01d5:  leave.s    IL_01ea
  }
  IL_01d7:  ldarg.0
  IL_01d8:  ldc.i4.s   -2
  IL_01da:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_01df:  ldarg.0
  IL_01e0:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_01e5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_01ea:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Conditional_ImplicitIndexIndexer_Struct_IndexAndValue_Async_04()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= await GetOffsetAsync(GetOffset(ref item));
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        item[^await GetOffsetAsync(GetOffset(ref item))] ??= await GetOffsetAsync(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position get for item '-1'
Position set for item '-2'
Position Length for item '-3'
Position get for item '-3'
Position set for item '-4'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      372 (0x174)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                int? V_2,
                int V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                int? V_5,
                System.Exception V_6)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0055
    IL_000a:  ldloc.0
    IL_000b:  ldc.i4.1
    IL_000c:  beq        IL_0100
    IL_0011:  ldarg.0
    IL_0012:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0017:  call       ""int Program.GetOffset<T>(ref T)""
    IL_001c:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0021:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0026:  stloc.s    V_4
    IL_0028:  ldloca.s   V_4
    IL_002a:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_002f:  brtrue.s   IL_0072
    IL_0031:  ldarg.0
    IL_0032:  ldc.i4.0
    IL_0033:  dup
    IL_0034:  stloc.0
    IL_0035:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003a:  ldarg.0
    IL_003b:  ldloc.s    V_4
    IL_003d:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0042:  ldarg.0
    IL_0043:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0048:  ldloca.s   V_4
    IL_004a:  ldarg.0
    IL_004b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0050:  leave      IL_0173
    IL_0055:  ldarg.0
    IL_0056:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005b:  stloc.s    V_4
    IL_005d:  ldarg.0
    IL_005e:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0063:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0069:  ldarg.0
    IL_006a:  ldc.i4.m1
    IL_006b:  dup
    IL_006c:  stloc.0
    IL_006d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0072:  ldloca.s   V_4
    IL_0074:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0079:  stloc.1
    IL_007a:  ldarg.0
    IL_007b:  ldarg.0
    IL_007c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0081:  constrained. ""T""
    IL_0087:  callvirt   ""int IMoveable.Length.get""
    IL_008c:  ldloc.1
    IL_008d:  sub
    IL_008e:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0093:  ldarg.0
    IL_0094:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0099:  ldarg.0
    IL_009a:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_009f:  constrained. ""T""
    IL_00a5:  callvirt   ""int? IMoveable.this[int].get""
    IL_00aa:  stloc.2
    IL_00ab:  ldloca.s   V_2
    IL_00ad:  call       ""readonly int int?.GetValueOrDefault()""
    IL_00b2:  stloc.3
    IL_00b3:  ldloca.s   V_2
    IL_00b5:  call       ""readonly bool int?.HasValue.get""
    IL_00ba:  brtrue     IL_0145
    IL_00bf:  ldarg.0
    IL_00c0:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00c5:  call       ""int Program.GetOffset<T>(ref T)""
    IL_00ca:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_00cf:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_00d4:  stloc.s    V_4
    IL_00d6:  ldloca.s   V_4
    IL_00d8:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_00dd:  brtrue.s   IL_011d
    IL_00df:  ldarg.0
    IL_00e0:  ldc.i4.1
    IL_00e1:  dup
    IL_00e2:  stloc.0
    IL_00e3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e8:  ldarg.0
    IL_00e9:  ldloc.s    V_4
    IL_00eb:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_00f0:  ldarg.0
    IL_00f1:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00f6:  ldloca.s   V_4
    IL_00f8:  ldarg.0
    IL_00f9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_00fe:  leave.s    IL_0173
    IL_0100:  ldarg.0
    IL_0101:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0106:  stloc.s    V_4
    IL_0108:  ldarg.0
    IL_0109:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_010e:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0114:  ldarg.0
    IL_0115:  ldc.i4.m1
    IL_0116:  dup
    IL_0117:  stloc.0
    IL_0118:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_011d:  ldloca.s   V_4
    IL_011f:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0124:  stloc.3
    IL_0125:  ldarg.0
    IL_0126:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_012b:  ldarg.0
    IL_012c:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0131:  ldloc.3
    IL_0132:  newobj     ""int?..ctor(int)""
    IL_0137:  dup
    IL_0138:  stloc.s    V_5
    IL_013a:  constrained. ""T""
    IL_0140:  callvirt   ""void IMoveable.this[int].set""
    IL_0145:  leave.s    IL_0160
  }
  catch System.Exception
  {
    IL_0147:  stloc.s    V_6
    IL_0149:  ldarg.0
    IL_014a:  ldc.i4.s   -2
    IL_014c:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0151:  ldarg.0
    IL_0152:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0157:  ldloc.s    V_6
    IL_0159:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_015e:  leave.s    IL_0173
  }
  IL_0160:  ldarg.0
  IL_0161:  ldc.i4.s   -2
  IL_0163:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0168:  ldarg.0
  IL_0169:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_016e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0173:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_ImplicitIndexIndexer_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        (item[^1], _) = (GetOffset(ref item), 0);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        (item[^1], _) = (GetOffset(ref item), 0);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position set for item '1'
Position Length for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       42 (0x2a)
  .maxstack  3
  .locals init (int V_0,
                int? V_1)
  IL_0000:  ldarg.0
  IL_0001:  dup
  IL_0002:  box        ""T""
  IL_0007:  callvirt   ""int IMoveable.Length.get""
  IL_000c:  ldc.i4.1
  IL_000d:  sub
  IL_000e:  stloc.0
  IL_000f:  ldloca.s   V_1
  IL_0011:  ldarga.s   V_0
  IL_0013:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0018:  call       ""int?..ctor(int)""
  IL_001d:  box        ""T""
  IL_0022:  ldloc.0
  IL_0023:  ldloc.1
  IL_0024:  callvirt   ""void IMoveable.this[int].set""
  IL_0029:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       75 (0x4b)
  .maxstack  3
  .locals init (T V_0,
                T& V_1,
                int V_2,
                T V_3,
                int? V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.1
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.1
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.0
  IL_001a:  ldloca.s   V_0
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.1
  IL_001f:  dup
  IL_0020:  constrained. ""T""
  IL_0026:  callvirt   ""int IMoveable.Length.get""
  IL_002b:  ldc.i4.1
  IL_002c:  sub
  IL_002d:  stloc.2
  IL_002e:  ldloca.s   V_4
  IL_0030:  ldarga.s   V_0
  IL_0032:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0037:  call       ""int?..ctor(int)""
  IL_003c:  ldloc.2
  IL_003d:  ldloc.s    V_4
  IL_003f:  constrained. ""T""
  IL_0045:  callvirt   ""void IMoveable.this[int].set""
  IL_004a:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_ImplicitIndexIndexer_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        (item[^1], _) = (GetOffset(ref item), 0);
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        (item[^1], _) = (GetOffset(ref item), 0);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position set for item '-1'
Position Length for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       45 (0x2d)
  .maxstack  3
  .locals init (int V_0,
                int? V_1)
  IL_0000:  ldarga.s   V_0
  IL_0002:  dup
  IL_0003:  constrained. ""T""
  IL_0009:  callvirt   ""int IMoveable.Length.get""
  IL_000e:  ldc.i4.1
  IL_000f:  sub
  IL_0010:  stloc.0
  IL_0011:  ldloca.s   V_1
  IL_0013:  ldarga.s   V_0
  IL_0015:  call       ""int Program.GetOffset<T>(ref T)""
  IL_001a:  call       ""int?..ctor(int)""
  IL_001f:  ldloc.0
  IL_0020:  ldloc.1
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""void IMoveable.this[int].set""
  IL_002c:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_ImplicitIndexIndexer_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        (item[^1], _) = (GetOffset(ref item), 0);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        (item[^1], _) = (GetOffset(ref item), 0);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position set for item '1'
Position Length for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       46 (0x2e)
  .maxstack  3
  .locals init (int V_0,
                int? V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  dup
  IL_0007:  box        ""T""
  IL_000c:  callvirt   ""int IMoveable.Length.get""
  IL_0011:  ldc.i4.1
  IL_0012:  sub
  IL_0013:  stloc.0
  IL_0014:  ldloca.s   V_1
  IL_0016:  ldarg.0
  IL_0017:  call       ""int Program.GetOffset<T>(ref T)""
  IL_001c:  call       ""int?..ctor(int)""
  IL_0021:  box        ""T""
  IL_0026:  ldloc.0
  IL_0027:  ldloc.1
  IL_0028:  callvirt   ""void IMoveable.this[int].set""
  IL_002d:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       73 (0x49)
  .maxstack  3
  .locals init (T V_0,
                T& V_1,
                int V_2,
                T V_3,
                int? V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_3
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.3
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_001d
  IL_0012:  ldloc.1
  IL_0013:  ldobj      ""T""
  IL_0018:  stloc.0
  IL_0019:  ldloca.s   V_0
  IL_001b:  br.s       IL_001e
  IL_001d:  ldloc.1
  IL_001e:  dup
  IL_001f:  constrained. ""T""
  IL_0025:  callvirt   ""int IMoveable.Length.get""
  IL_002a:  ldc.i4.1
  IL_002b:  sub
  IL_002c:  stloc.2
  IL_002d:  ldloca.s   V_4
  IL_002f:  ldarg.0
  IL_0030:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0035:  call       ""int?..ctor(int)""
  IL_003a:  ldloc.2
  IL_003b:  ldloc.s    V_4
  IL_003d:  constrained. ""T""
  IL_0043:  callvirt   ""void IMoveable.this[int].set""
  IL_0048:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_ImplicitIndexIndexer_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        (item[^1], _) = (GetOffset(ref item), 0);
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        (item[^1], _) = (GetOffset(ref item), 0);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position set for item '-1'
Position Length for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       43 (0x2b)
  .maxstack  3
  .locals init (int V_0,
              int? V_1)
  IL_0000:  ldarg.0
  IL_0001:  dup
  IL_0002:  constrained. ""T""
  IL_0008:  callvirt   ""int IMoveable.Length.get""
  IL_000d:  ldc.i4.1
  IL_000e:  sub
  IL_000f:  stloc.0
  IL_0010:  ldloca.s   V_1
  IL_0012:  ldarg.0
  IL_0013:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0018:  call       ""int?..ctor(int)""
  IL_001d:  ldloc.0
  IL_001e:  ldloc.1
  IL_001f:  constrained. ""T""
  IL_0025:  callvirt   ""void IMoveable.this[int].set""
  IL_002a:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_ImplicitIndexIndexer_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        (item[^1], _) = (await GetOffsetAsync(GetOffset(ref item)), 0);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        (item[^1], _) = (await GetOffsetAsync(GetOffset(ref item)), 0);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position set for item '1'
Position Length for item '2'
Position set for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      234 (0xea)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                int? V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006d
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldarg.0
    IL_0018:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_001d:  box        ""T""
    IL_0022:  callvirt   ""int IMoveable.Length.get""
    IL_0027:  ldc.i4.1
    IL_0028:  sub
    IL_0029:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_002e:  ldarg.0
    IL_002f:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0034:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0039:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_003e:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0043:  stloc.3
    IL_0044:  ldloca.s   V_3
    IL_0046:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_004b:  brtrue.s   IL_0089
    IL_004d:  ldarg.0
    IL_004e:  ldc.i4.0
    IL_004f:  dup
    IL_0050:  stloc.0
    IL_0051:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0056:  ldarg.0
    IL_0057:  ldloc.3
    IL_0058:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005d:  ldarg.0
    IL_005e:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0063:  ldloca.s   V_3
    IL_0065:  ldarg.0
    IL_0066:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_006b:  leave.s    IL_00e9
    IL_006d:  ldarg.0
    IL_006e:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0073:  stloc.3
    IL_0074:  ldarg.0
    IL_0075:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_007a:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0080:  ldarg.0
    IL_0081:  ldc.i4.m1
    IL_0082:  dup
    IL_0083:  stloc.0
    IL_0084:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0089:  ldloca.s   V_3
    IL_008b:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0090:  stloc.1
    IL_0091:  ldloc.1
    IL_0092:  newobj     ""int?..ctor(int)""
    IL_0097:  stloc.2
    IL_0098:  ldarg.0
    IL_0099:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_009e:  box        ""T""
    IL_00a3:  ldarg.0
    IL_00a4:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap2""
    IL_00a9:  ldloc.2
    IL_00aa:  callvirt   ""void IMoveable.this[int].set""
    IL_00af:  ldarg.0
    IL_00b0:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00b5:  initobj    ""T""
    IL_00bb:  leave.s    IL_00d6
  }
  catch System.Exception
  {
    IL_00bd:  stloc.s    V_4
    IL_00bf:  ldarg.0
    IL_00c0:  ldc.i4.s   -2
    IL_00c2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00c7:  ldarg.0
    IL_00c8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00cd:  ldloc.s    V_4
    IL_00cf:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00d4:  leave.s    IL_00e9
  }
  IL_00d6:  ldarg.0
  IL_00d7:  ldc.i4.s   -2
  IL_00d9:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00de:  ldarg.0
  IL_00df:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00e4:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00e9:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      309 (0x135)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                int? V_2,
                T V_3,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_4,
                System.Exception V_5)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse    IL_009e
    IL_000d:  ldloca.s   V_3
    IL_000f:  initobj    ""T""
    IL_0015:  ldloc.3
    IL_0016:  box        ""T""
    IL_001b:  brtrue.s   IL_0029
    IL_001d:  ldarg.0
    IL_001e:  ldarg.0
    IL_001f:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0024:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0029:  ldarg.0
    IL_002a:  ldloca.s   V_3
    IL_002c:  initobj    ""T""
    IL_0032:  ldloc.3
    IL_0033:  box        ""T""
    IL_0038:  brtrue.s   IL_0042
    IL_003a:  ldarg.0
    IL_003b:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0040:  br.s       IL_0048
    IL_0042:  ldarg.0
    IL_0043:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0048:  constrained. ""T""
    IL_004e:  callvirt   ""int IMoveable.Length.get""
    IL_0053:  ldc.i4.1
    IL_0054:  sub
    IL_0055:  stfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_005a:  ldarg.0
    IL_005b:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0060:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0065:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_006a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_006f:  stloc.s    V_4
    IL_0071:  ldloca.s   V_4
    IL_0073:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0078:  brtrue.s   IL_00bb
    IL_007a:  ldarg.0
    IL_007b:  ldc.i4.0
    IL_007c:  dup
    IL_007d:  stloc.0
    IL_007e:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0083:  ldarg.0
    IL_0084:  ldloc.s    V_4
    IL_0086:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_008b:  ldarg.0
    IL_008c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0091:  ldloca.s   V_4
    IL_0093:  ldarg.0
    IL_0094:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0099:  leave      IL_0134
    IL_009e:  ldarg.0
    IL_009f:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00a4:  stloc.s    V_4
    IL_00a6:  ldarg.0
    IL_00a7:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_00ac:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_00b2:  ldarg.0
    IL_00b3:  ldc.i4.m1
    IL_00b4:  dup
    IL_00b5:  stloc.0
    IL_00b6:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00bb:  ldloca.s   V_4
    IL_00bd:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_00c2:  stloc.1
    IL_00c3:  ldloc.1
    IL_00c4:  newobj     ""int?..ctor(int)""
    IL_00c9:  stloc.2
    IL_00ca:  ldloca.s   V_3
    IL_00cc:  initobj    ""T""
    IL_00d2:  ldloc.3
    IL_00d3:  box        ""T""
    IL_00d8:  brtrue.s   IL_00e2
    IL_00da:  ldarg.0
    IL_00db:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00e0:  br.s       IL_00e8
    IL_00e2:  ldarg.0
    IL_00e3:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00e8:  ldarg.0
    IL_00e9:  ldfld      ""int Program.<Shift2>d__2<T>.<>7__wrap2""
    IL_00ee:  ldloc.2
    IL_00ef:  constrained. ""T""
    IL_00f5:  callvirt   ""void IMoveable.this[int].set""
    IL_00fa:  ldarg.0
    IL_00fb:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0100:  initobj    ""T""
    IL_0106:  leave.s    IL_0121
  }
  catch System.Exception
  {
    IL_0108:  stloc.s    V_5
    IL_010a:  ldarg.0
    IL_010b:  ldc.i4.s   -2
    IL_010d:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0112:  ldarg.0
    IL_0113:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0118:  ldloc.s    V_5
    IL_011a:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_011f:  leave.s    IL_0134
  }
  IL_0121:  ldarg.0
  IL_0122:  ldc.i4.s   -2
  IL_0124:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0129:  ldarg.0
  IL_012a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_012f:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0134:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_Assignment_Deconstruction_ImplicitIndexIndexer_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    int? this[int x] {get;set;}
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public int? this[int x]
    {
        get
        {
            Console.WriteLine(""Position get for item '{0}'"", Name);
            return null;
        }
        set
        {
            Console.WriteLine(""Position set for item '{0}'"", Name);
        }
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 0;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        (item[^1], _) = (await GetOffsetAsync(GetOffset(ref item)), 0);
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        (item[^1], _) = (await GetOffsetAsync(GetOffset(ref item)), 0);
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position set for item '-1'
Position Length for item '2'
Position set for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      212 (0xd4)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                int? V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0062
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  constrained. ""T""
    IL_0017:  callvirt   ""int IMoveable.Length.get""
    IL_001c:  ldc.i4.1
    IL_001d:  sub
    IL_001e:  stfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0023:  ldarg.0
    IL_0024:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0029:  call       ""int Program.GetOffset<T>(ref T)""
    IL_002e:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0033:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_0038:  stloc.3
    IL_0039:  ldloca.s   V_3
    IL_003b:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0040:  brtrue.s   IL_007e
    IL_0042:  ldarg.0
    IL_0043:  ldc.i4.0
    IL_0044:  dup
    IL_0045:  stloc.0
    IL_0046:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_004b:  ldarg.0
    IL_004c:  ldloc.3
    IL_004d:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0052:  ldarg.0
    IL_0053:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0058:  ldloca.s   V_3
    IL_005a:  ldarg.0
    IL_005b:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0060:  leave.s    IL_00d3
    IL_0062:  ldarg.0
    IL_0063:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  stloc.3
    IL_0069:  ldarg.0
    IL_006a:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_006f:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_0075:  ldarg.0
    IL_0076:  ldc.i4.m1
    IL_0077:  dup
    IL_0078:  stloc.0
    IL_0079:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_007e:  ldloca.s   V_3
    IL_0080:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_0085:  stloc.1
    IL_0086:  ldloc.1
    IL_0087:  newobj     ""int?..ctor(int)""
    IL_008c:  stloc.2
    IL_008d:  ldarg.0
    IL_008e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0093:  ldarg.0
    IL_0094:  ldfld      ""int Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0099:  ldloc.2
    IL_009a:  constrained. ""T""
    IL_00a0:  callvirt   ""void IMoveable.this[int].set""
    IL_00a5:  leave.s    IL_00c0
  }
  catch System.Exception
  {
    IL_00a7:  stloc.s    V_4
    IL_00a9:  ldarg.0
    IL_00aa:  ldc.i4.s   -2
    IL_00ac:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b1:  ldarg.0
    IL_00b2:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00b7:  ldloc.s    V_4
    IL_00b9:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00be:  leave.s    IL_00d3
  }
  IL_00c0:  ldarg.0
  IL_00c1:  ldc.i4.s   -2
  IL_00c3:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00c8:  ldarg.0
  IL_00c9:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00ce:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00d3:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeExpression_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        _ = item[0..^GetOffset(ref item)];
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        _ = item[0..^GetOffset(ref item)];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position Slice for item '1'
Position Length for item '2'
Position Slice for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       37 (0x25)
  .maxstack  4
  .locals init (T V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.1
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  ldc.i4.0
  IL_0011:  ldloc.0
  IL_0012:  box        ""T""
  IL_0017:  callvirt   ""int IMoveable.Length.get""
  IL_001c:  ldloc.1
  IL_001d:  sub
  IL_001e:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_0023:  pop
  IL_0024:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       70 (0x46)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_4
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_4
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldarga.s   V_0
  IL_0023:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0028:  stloc.3
  IL_0029:  ldloc.0
  IL_002a:  ldc.i4.0
  IL_002b:  ldloc.0
  IL_002c:  constrained. ""T""
  IL_0032:  callvirt   ""int IMoveable.Length.get""
  IL_0037:  ldloc.3
  IL_0038:  sub
  IL_0039:  constrained. ""T""
  IL_003f:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_0044:  pop
  IL_0045:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeExpression_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        _ = item[0..^GetOffset(ref item)];
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        _ = item[0..^GetOffset(ref item)];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position Slice for item '-1'
Position Length for item '-2'
Position Slice for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       40 (0x28)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.0
  IL_0003:  ldarga.s   V_0
  IL_0005:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000a:  stloc.1
  IL_000b:  ldloc.0
  IL_000c:  ldc.i4.0
  IL_000d:  ldloc.0
  IL_000e:  constrained. ""T""
  IL_0014:  callvirt   ""int IMoveable.Length.get""
  IL_0019:  ldloc.1
  IL_001a:  sub
  IL_001b:  constrained. ""T""
  IL_0021:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_0026:  pop
  IL_0027:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeExpression_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        _ = item[0..^GetOffset(ref item)];
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        _ = item[0..^GetOffset(ref item)];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position Slice for item '1'
Position Length for item '2'
Position Slice for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       41 (0x29)
  .maxstack  4
  .locals init (T V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  stloc.0
  IL_0007:  ldarg.0
  IL_0008:  call       ""int Program.GetOffset<T>(ref T)""
  IL_000d:  stloc.1
  IL_000e:  ldloc.0
  IL_000f:  box        ""T""
  IL_0014:  ldc.i4.0
  IL_0015:  ldloc.0
  IL_0016:  box        ""T""
  IL_001b:  callvirt   ""int IMoveable.Length.get""
  IL_0020:  ldloc.1
  IL_0021:  sub
  IL_0022:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_0027:  pop
  IL_0028:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size       68 (0x44)
  .maxstack  4
  .locals init (T& V_0,
            T V_1,
            T& V_2,
            int V_3,
            T V_4)
  IL_0000:  ldarg.0
  IL_0001:  stloc.2
  IL_0002:  ldloca.s   V_4
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_4
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.2
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.1
  IL_001a:  ldloca.s   V_1
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.2
  IL_001f:  stloc.0
  IL_0020:  ldarg.0
  IL_0021:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0026:  stloc.3
  IL_0027:  ldloc.0
  IL_0028:  ldc.i4.0
  IL_0029:  ldloc.0
  IL_002a:  constrained. ""T""
  IL_0030:  callvirt   ""int IMoveable.Length.get""
  IL_0035:  ldloc.3
  IL_0036:  sub
  IL_0037:  constrained. ""T""
  IL_003d:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_0042:  pop
  IL_0043:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeExpression_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        _ = item[0..^GetOffset(ref item)];
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        _ = item[0..^GetOffset(ref item)];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position Slice for item '-1'
Position Length for item '-2'
Position Slice for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       38 (0x26)
  .maxstack  4
  .locals init (T& V_0,
                int V_1)
  IL_0000:  ldarg.0
  IL_0001:  stloc.0
  IL_0002:  ldarg.0
  IL_0003:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.1
  IL_0009:  ldloc.0
  IL_000a:  ldc.i4.0
  IL_000b:  ldloc.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int IMoveable.Length.get""
  IL_0017:  ldloc.1
  IL_0018:  sub
  IL_0019:  constrained. ""T""
  IL_001f:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_0024:  pop
  IL_0025:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeExpression_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        _ = item[0..^await GetOffsetAsync(GetOffset(ref item))];
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        _ = item[0..^await GetOffsetAsync(GetOffset(ref item))];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position Slice for item '1'
Position Length for item '2'
Position Slice for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      217 (0xd9)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0058
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_002b:  stloc.2
    IL_002c:  ldloca.s   V_2
    IL_002e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0033:  brtrue.s   IL_0074
    IL_0035:  ldarg.0
    IL_0036:  ldc.i4.0
    IL_0037:  dup
    IL_0038:  stloc.0
    IL_0039:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003e:  ldarg.0
    IL_003f:  ldloc.2
    IL_0040:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0045:  ldarg.0
    IL_0046:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004b:  ldloca.s   V_2
    IL_004d:  ldarg.0
    IL_004e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0053:  leave      IL_00d8
    IL_0058:  ldarg.0
    IL_0059:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_005e:  stloc.2
    IL_005f:  ldarg.0
    IL_0060:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0065:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_006b:  ldarg.0
    IL_006c:  ldc.i4.m1
    IL_006d:  dup
    IL_006e:  stloc.0
    IL_006f:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0074:  ldloca.s   V_2
    IL_0076:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_007b:  stloc.1
    IL_007c:  ldarg.0
    IL_007d:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0082:  box        ""T""
    IL_0087:  ldc.i4.0
    IL_0088:  ldarg.0
    IL_0089:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_008e:  box        ""T""
    IL_0093:  callvirt   ""int IMoveable.Length.get""
    IL_0098:  ldloc.1
    IL_0099:  sub
    IL_009a:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
    IL_009f:  pop
    IL_00a0:  ldarg.0
    IL_00a1:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00a6:  initobj    ""T""
    IL_00ac:  leave.s    IL_00c5
  }
  catch System.Exception
  {
    IL_00ae:  stloc.3
    IL_00af:  ldarg.0
    IL_00b0:  ldc.i4.s   -2
    IL_00b2:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00b7:  ldarg.0
    IL_00b8:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00bd:  ldloc.3
    IL_00be:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00c3:  leave.s    IL_00d8
  }
  IL_00c5:  ldarg.0
  IL_00c6:  ldc.i4.s   -2
  IL_00c8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00cd:  ldarg.0
  IL_00ce:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00d3:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00d8:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      285 (0x11d)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0068
    IL_000a:  ldloca.s   V_2
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.2
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0021:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.3
    IL_003c:  ldloca.s   V_3
    IL_003e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0043:  brtrue.s   IL_0084
    IL_0045:  ldarg.0
    IL_0046:  ldc.i4.0
    IL_0047:  dup
    IL_0048:  stloc.0
    IL_0049:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_004e:  ldarg.0
    IL_004f:  ldloc.3
    IL_0050:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005b:  ldloca.s   V_3
    IL_005d:  ldarg.0
    IL_005e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift2>d__2<T>)""
    IL_0063:  leave      IL_011c
    IL_0068:  ldarg.0
    IL_0069:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_006e:  stloc.3
    IL_006f:  ldarg.0
    IL_0070:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift2>d__2<T>.<>u__1""
    IL_0075:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007b:  ldarg.0
    IL_007c:  ldc.i4.m1
    IL_007d:  dup
    IL_007e:  stloc.0
    IL_007f:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0084:  ldloca.s   V_3
    IL_0086:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008b:  stloc.1
    IL_008c:  ldloca.s   V_2
    IL_008e:  initobj    ""T""
    IL_0094:  ldloc.2
    IL_0095:  box        ""T""
    IL_009a:  brtrue.s   IL_00a4
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a2:  br.s       IL_00aa
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00aa:  ldc.i4.0
    IL_00ab:  ldloca.s   V_2
    IL_00ad:  initobj    ""T""
    IL_00b3:  ldloc.2
    IL_00b4:  box        ""T""
    IL_00b9:  brtrue.s   IL_00c3
    IL_00bb:  ldarg.0
    IL_00bc:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00c1:  br.s       IL_00c9
    IL_00c3:  ldarg.0
    IL_00c4:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00c9:  constrained. ""T""
    IL_00cf:  callvirt   ""int IMoveable.Length.get""
    IL_00d4:  ldloc.1
    IL_00d5:  sub
    IL_00d6:  constrained. ""T""
    IL_00dc:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
    IL_00e1:  pop
    IL_00e2:  ldarg.0
    IL_00e3:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00e8:  initobj    ""T""
    IL_00ee:  leave.s    IL_0109
  }
  catch System.Exception
  {
    IL_00f0:  stloc.s    V_4
    IL_00f2:  ldarg.0
    IL_00f3:  ldc.i4.s   -2
    IL_00f5:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_00fa:  ldarg.0
    IL_00fb:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_0100:  ldloc.s    V_4
    IL_0102:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0107:  leave.s    IL_011c
  }
  IL_0109:  ldarg.0
  IL_010a:  ldc.i4.s   -2
  IL_010c:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0111:  ldarg.0
  IL_0112:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0117:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_011c:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeExpression_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        _ = item[0..^await GetOffsetAsync(GetOffset(ref item))];
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        _ = item[0..^await GetOffsetAsync(GetOffset(ref item))];
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position Slice for item '-1'
Position Length for item '-2'
Position Slice for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      192 (0xc0)
  .maxstack  4
  .locals init (int V_0,
                int V_1,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_2,
                System.Exception V_3)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0049
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_001f:  stloc.2
    IL_0020:  ldloca.s   V_2
    IL_0022:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0027:  brtrue.s   IL_0065
    IL_0029:  ldarg.0
    IL_002a:  ldc.i4.0
    IL_002b:  dup
    IL_002c:  stloc.0
    IL_002d:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0032:  ldarg.0
    IL_0033:  ldloc.2
    IL_0034:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0039:  ldarg.0
    IL_003a:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_003f:  ldloca.s   V_2
    IL_0041:  ldarg.0
    IL_0042:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Shift1>d__1<T>)""
    IL_0047:  leave.s    IL_00bf
    IL_0049:  ldarg.0
    IL_004a:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_004f:  stloc.2
    IL_0050:  ldarg.0
    IL_0051:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Shift1>d__1<T>.<>u__1""
    IL_0056:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_005c:  ldarg.0
    IL_005d:  ldc.i4.m1
    IL_005e:  dup
    IL_005f:  stloc.0
    IL_0060:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0065:  ldloca.s   V_2
    IL_0067:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_006c:  stloc.1
    IL_006d:  ldarg.0
    IL_006e:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0073:  ldc.i4.0
    IL_0074:  ldarg.0
    IL_0075:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_007a:  constrained. ""T""
    IL_0080:  callvirt   ""int IMoveable.Length.get""
    IL_0085:  ldloc.1
    IL_0086:  sub
    IL_0087:  constrained. ""T""
    IL_008d:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
    IL_0092:  pop
    IL_0093:  leave.s    IL_00ac
  }
  catch System.Exception
  {
    IL_0095:  stloc.3
    IL_0096:  ldarg.0
    IL_0097:  ldc.i4.s   -2
    IL_0099:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_009e:  ldarg.0
    IL_009f:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00a4:  ldloc.3
    IL_00a5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00aa:  leave.s    IL_00bf
  }
  IL_00ac:  ldarg.0
  IL_00ad:  ldc.i4.s   -2
  IL_00af:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00b4:  ldarg.0
  IL_00b5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00ba:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00bf:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeValue_Class()
        {
            var source = @"
using System;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : class, IMoveable
    {
        _ = item[GetOffset(ref item)];
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        _ = item[GetOffset(ref item)];
    }
    
    static int value = 0;
    static Range GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0..1;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position Slice for item '1'
Position Length for item '2'
Position Slice for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       73 (0x49)
  .maxstack  3
  .locals init (System.Range V_0,
                int V_1,
                int V_2,
                int V_3,
                System.Index V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldarga.s   V_0
  IL_0003:  call       ""System.Range Program.GetOffset<T>(ref T)""
  IL_0008:  stloc.0
  IL_0009:  dup
  IL_000a:  box        ""T""
  IL_000f:  callvirt   ""int IMoveable.Length.get""
  IL_0014:  stloc.1
  IL_0015:  ldloca.s   V_0
  IL_0017:  call       ""System.Index System.Range.Start.get""
  IL_001c:  stloc.s    V_4
  IL_001e:  ldloca.s   V_4
  IL_0020:  ldloc.1
  IL_0021:  call       ""int System.Index.GetOffset(int)""
  IL_0026:  stloc.2
  IL_0027:  ldloca.s   V_0
  IL_0029:  call       ""System.Index System.Range.End.get""
  IL_002e:  stloc.s    V_4
  IL_0030:  ldloca.s   V_4
  IL_0032:  ldloc.1
  IL_0033:  call       ""int System.Index.GetOffset(int)""
  IL_0038:  ldloc.2
  IL_0039:  sub
  IL_003a:  stloc.3
  IL_003b:  box        ""T""
  IL_0040:  ldloc.2
  IL_0041:  ldloc.3
  IL_0042:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_0047:  pop
  IL_0048:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      111 (0x6f)
  .maxstack  3
  .locals init (T V_0,
                T& V_1,
                System.Range V_2,
                int V_3,
                int V_4,
                int V_5,
                T V_6,
                System.Index V_7)
  IL_0000:  ldarga.s   V_0
  IL_0002:  stloc.1
  IL_0003:  ldloca.s   V_6
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_6
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.1
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.0
  IL_001b:  ldloca.s   V_0
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.1
  IL_0020:  ldarga.s   V_0
  IL_0022:  call       ""System.Range Program.GetOffset<T>(ref T)""
  IL_0027:  stloc.2
  IL_0028:  dup
  IL_0029:  constrained. ""T""
  IL_002f:  callvirt   ""int IMoveable.Length.get""
  IL_0034:  stloc.3
  IL_0035:  ldloca.s   V_2
  IL_0037:  call       ""System.Index System.Range.Start.get""
  IL_003c:  stloc.s    V_7
  IL_003e:  ldloca.s   V_7
  IL_0040:  ldloc.3
  IL_0041:  call       ""int System.Index.GetOffset(int)""
  IL_0046:  stloc.s    V_4
  IL_0048:  ldloca.s   V_2
  IL_004a:  call       ""System.Index System.Range.End.get""
  IL_004f:  stloc.s    V_7
  IL_0051:  ldloca.s   V_7
  IL_0053:  ldloc.3
  IL_0054:  call       ""int System.Index.GetOffset(int)""
  IL_0059:  ldloc.s    V_4
  IL_005b:  sub
  IL_005c:  stloc.s    V_5
  IL_005e:  ldloc.s    V_4
  IL_0060:  ldloc.s    V_5
  IL_0062:  constrained. ""T""
  IL_0068:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_006d:  pop
  IL_006e:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeValue_Struct()
        {
            var source = @"
using System;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(item1);

        var item2 = new Item {Name = ""2""};
        Shift2(item2);
    }

    static void Shift1<T>(T item) where T : struct, IMoveable
    {
        _ = item[GetOffset(ref item)];
    }

    static void Shift2<T>(T item) where T : IMoveable
    {
        _ = item[GetOffset(ref item)];
    }
    
    static int value = 0;
    static Range GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0..1;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position Slice for item '-1'
Position Length for item '-2'
Position Slice for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       76 (0x4c)
  .maxstack  3
  .locals init (System.Range V_0,
                int V_1,
                int V_2,
                int V_3,
                System.Index V_4)
  IL_0000:  ldarga.s   V_0
  IL_0002:  ldarga.s   V_0
  IL_0004:  call       ""System.Range Program.GetOffset<T>(ref T)""
  IL_0009:  stloc.0
  IL_000a:  dup
  IL_000b:  constrained. ""T""
  IL_0011:  callvirt   ""int IMoveable.Length.get""
  IL_0016:  stloc.1
  IL_0017:  ldloca.s   V_0
  IL_0019:  call       ""System.Index System.Range.Start.get""
  IL_001e:  stloc.s    V_4
  IL_0020:  ldloca.s   V_4
  IL_0022:  ldloc.1
  IL_0023:  call       ""int System.Index.GetOffset(int)""
  IL_0028:  stloc.2
  IL_0029:  ldloca.s   V_0
  IL_002b:  call       ""System.Index System.Range.End.get""
  IL_0030:  stloc.s    V_4
  IL_0032:  ldloca.s   V_4
  IL_0034:  ldloc.1
  IL_0035:  call       ""int System.Index.GetOffset(int)""
  IL_003a:  ldloc.2
  IL_003b:  sub
  IL_003c:  stloc.3
  IL_003d:  ldloc.2
  IL_003e:  ldloc.3
  IL_003f:  constrained. ""T""
  IL_0045:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_004a:  pop
  IL_004b:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeValue_Class_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : class, IMoveable
    {
        _ = item[GetOffset(ref item)];
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        _ = item[GetOffset(ref item)];
    }
    
    static int value = 0;
    static Range GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0..1;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position Slice for item '1'
Position Length for item '2'
Position Slice for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       77 (0x4d)
  .maxstack  3
  .locals init (System.Range V_0,
                int V_1,
                int V_2,
                int V_3,
                System.Index V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldobj      ""T""
  IL_0006:  ldarg.0
  IL_0007:  call       ""System.Range Program.GetOffset<T>(ref T)""
  IL_000c:  stloc.0
  IL_000d:  dup
  IL_000e:  box        ""T""
  IL_0013:  callvirt   ""int IMoveable.Length.get""
  IL_0018:  stloc.1
  IL_0019:  ldloca.s   V_0
  IL_001b:  call       ""System.Index System.Range.Start.get""
  IL_0020:  stloc.s    V_4
  IL_0022:  ldloca.s   V_4
  IL_0024:  ldloc.1
  IL_0025:  call       ""int System.Index.GetOffset(int)""
  IL_002a:  stloc.2
  IL_002b:  ldloca.s   V_0
  IL_002d:  call       ""System.Index System.Range.End.get""
  IL_0032:  stloc.s    V_4
  IL_0034:  ldloca.s   V_4
  IL_0036:  ldloc.1
  IL_0037:  call       ""int System.Index.GetOffset(int)""
  IL_003c:  ldloc.2
  IL_003d:  sub
  IL_003e:  stloc.3
  IL_003f:  box        ""T""
  IL_0044:  ldloc.2
  IL_0045:  ldloc.3
  IL_0046:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_004b:  pop
  IL_004c:  ret
}
");

            verifier.VerifyIL("Program.Shift2<T>",
@"
{
  // Code size      109 (0x6d)
  .maxstack  3
  .locals init (T V_0,
                T& V_1,
                System.Range V_2,
                int V_3,
                int V_4,
                int V_5,
                T V_6,
                System.Index V_7)
  IL_0000:  ldarg.0
  IL_0001:  stloc.1
  IL_0002:  ldloca.s   V_6
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.s    V_6
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.1
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.0
  IL_001a:  ldloca.s   V_0
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.1
  IL_001f:  ldarg.0
  IL_0020:  call       ""System.Range Program.GetOffset<T>(ref T)""
  IL_0025:  stloc.2
  IL_0026:  dup
  IL_0027:  constrained. ""T""
  IL_002d:  callvirt   ""int IMoveable.Length.get""
  IL_0032:  stloc.3
  IL_0033:  ldloca.s   V_2
  IL_0035:  call       ""System.Index System.Range.Start.get""
  IL_003a:  stloc.s    V_7
  IL_003c:  ldloca.s   V_7
  IL_003e:  ldloc.3
  IL_003f:  call       ""int System.Index.GetOffset(int)""
  IL_0044:  stloc.s    V_4
  IL_0046:  ldloca.s   V_2
  IL_0048:  call       ""System.Index System.Range.End.get""
  IL_004d:  stloc.s    V_7
  IL_004f:  ldloca.s   V_7
  IL_0051:  ldloc.3
  IL_0052:  call       ""int System.Index.GetOffset(int)""
  IL_0057:  ldloc.s    V_4
  IL_0059:  sub
  IL_005a:  stloc.s    V_5
  IL_005c:  ldloc.s    V_4
  IL_005e:  ldloc.s    V_5
  IL_0060:  constrained. ""T""
  IL_0066:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_006b:  pop
  IL_006c:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeValue_Struct_Ref()
        {
            var source = @"
using System;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Shift1(ref item1);

        var item2 = new Item {Name = ""2""};
        Shift2(ref item2);
    }

    static void Shift1<T>(ref T item) where T : struct, IMoveable
    {
        _ = item[GetOffset(ref item)];
    }

    static void Shift2<T>(ref T item) where T : IMoveable
    {
        _ = item[GetOffset(ref item)];
    }
    
    static int value = 0;
    static Range GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0..1;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position Slice for item '-1'
Position Length for item '-2'
Position Slice for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Shift1<T>",
@"
{
  // Code size       74 (0x4a)
  .maxstack  3
  .locals init (System.Range V_0,
                int V_1,
                int V_2,
                int V_3,
                System.Index V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldarg.0
  IL_0002:  call       ""System.Range Program.GetOffset<T>(ref T)""
  IL_0007:  stloc.0
  IL_0008:  dup
  IL_0009:  constrained. ""T""
  IL_000f:  callvirt   ""int IMoveable.Length.get""
  IL_0014:  stloc.1
  IL_0015:  ldloca.s   V_0
  IL_0017:  call       ""System.Index System.Range.Start.get""
  IL_001c:  stloc.s    V_4
  IL_001e:  ldloca.s   V_4
  IL_0020:  ldloc.1
  IL_0021:  call       ""int System.Index.GetOffset(int)""
  IL_0026:  stloc.2
  IL_0027:  ldloca.s   V_0
  IL_0029:  call       ""System.Index System.Range.End.get""
  IL_002e:  stloc.s    V_4
  IL_0030:  ldloca.s   V_4
  IL_0032:  ldloc.1
  IL_0033:  call       ""int System.Index.GetOffset(int)""
  IL_0038:  ldloc.2
  IL_0039:  sub
  IL_003a:  stloc.3
  IL_003b:  ldloc.2
  IL_003c:  ldloc.3
  IL_003d:  constrained. ""T""
  IL_0043:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
  IL_0048:  pop
  IL_0049:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeValue_Class_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

class Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : class, IMoveable
    {
        _ = item[await GetOffsetAsync(GetOffset(ref item))];
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        _ = item[await GetOffsetAsync(GetOffset(ref item))];
    }
    
    static int value = 0;
    static Range GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0..1;
    }

    static async Task<Range> GetOffsetAsync(Range i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '1'
Position Slice for item '1'
Position Length for item '2'
Position Slice for item '2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      262 (0x106)
  .maxstack  3
  .locals init (int V_0,
                System.Range V_1,
                int V_2,
                int V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<System.Range> V_5,
                System.Index V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_005a
    IL_000a:  ldarg.0
    IL_000b:  ldarg.0
    IL_000c:  ldfld      ""T Program.<Shift1>d__1<T>.item""
    IL_0011:  stfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0016:  ldarg.0
    IL_0017:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_001c:  call       ""System.Range Program.GetOffset<T>(ref T)""
    IL_0021:  call       ""System.Threading.Tasks.Task<System.Range> Program.GetOffsetAsync(System.Range)""
    IL_0026:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> System.Threading.Tasks.Task<System.Range>.GetAwaiter()""
    IL_002b:  stloc.s    V_5
    IL_002d:  ldloca.s   V_5
    IL_002f:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<System.Range>.IsCompleted.get""
    IL_0034:  brtrue.s   IL_0077
    IL_0036:  ldarg.0
    IL_0037:  ldc.i4.0
    IL_0038:  dup
    IL_0039:  stloc.0
    IL_003a:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_003f:  ldarg.0
    IL_0040:  ldloc.s    V_5
    IL_0042:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift1>d__1<T>.<>u__1""
    IL_0047:  ldarg.0
    IL_0048:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_004d:  ldloca.s   V_5
    IL_004f:  ldarg.0
    IL_0050:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<System.Range>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<System.Range>, ref Program.<Shift1>d__1<T>)""
    IL_0055:  leave      IL_0105
    IL_005a:  ldarg.0
    IL_005b:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift1>d__1<T>.<>u__1""
    IL_0060:  stloc.s    V_5
    IL_0062:  ldarg.0
    IL_0063:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift1>d__1<T>.<>u__1""
    IL_0068:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<System.Range>""
    IL_006e:  ldarg.0
    IL_006f:  ldc.i4.m1
    IL_0070:  dup
    IL_0071:  stloc.0
    IL_0072:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0077:  ldloca.s   V_5
    IL_0079:  call       ""System.Range System.Runtime.CompilerServices.TaskAwaiter<System.Range>.GetResult()""
    IL_007e:  stloc.1
    IL_007f:  ldarg.0
    IL_0080:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_0085:  box        ""T""
    IL_008a:  callvirt   ""int IMoveable.Length.get""
    IL_008f:  stloc.2
    IL_0090:  ldloca.s   V_1
    IL_0092:  call       ""System.Index System.Range.Start.get""
    IL_0097:  stloc.s    V_6
    IL_0099:  ldloca.s   V_6
    IL_009b:  ldloc.2
    IL_009c:  call       ""int System.Index.GetOffset(int)""
    IL_00a1:  stloc.3
    IL_00a2:  ldloca.s   V_1
    IL_00a4:  call       ""System.Index System.Range.End.get""
    IL_00a9:  stloc.s    V_6
    IL_00ab:  ldloca.s   V_6
    IL_00ad:  ldloc.2
    IL_00ae:  call       ""int System.Index.GetOffset(int)""
    IL_00b3:  ldloc.3
    IL_00b4:  sub
    IL_00b5:  stloc.s    V_4
    IL_00b7:  ldarg.0
    IL_00b8:  ldfld      ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00bd:  box        ""T""
    IL_00c2:  ldloc.3
    IL_00c3:  ldloc.s    V_4
    IL_00c5:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
    IL_00ca:  pop
    IL_00cb:  ldarg.0
    IL_00cc:  ldflda     ""T Program.<Shift1>d__1<T>.<>7__wrap1""
    IL_00d1:  initobj    ""T""
    IL_00d7:  leave.s    IL_00f2
  }
  catch System.Exception
  {
    IL_00d9:  stloc.s    V_7
    IL_00db:  ldarg.0
    IL_00dc:  ldc.i4.s   -2
    IL_00de:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00e3:  ldarg.0
    IL_00e4:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00e9:  ldloc.s    V_7
    IL_00eb:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00f0:  leave.s    IL_0105
  }
  IL_00f2:  ldarg.0
  IL_00f3:  ldc.i4.s   -2
  IL_00f5:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00fa:  ldarg.0
  IL_00fb:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_0100:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_0105:  ret
}
");

            verifier.VerifyIL("Program.<Shift2>d__2<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      331 (0x14b)
  .maxstack  3
  .locals init (int V_0,
                System.Range V_1,
                int V_2,
                int V_3,
                int V_4,
                T V_5,
                System.Runtime.CompilerServices.TaskAwaiter<System.Range> V_6,
                System.Index V_7,
                System.Exception V_8)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_006b
    IL_000a:  ldloca.s   V_5
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.s    V_5
    IL_0014:  box        ""T""
    IL_0019:  brtrue.s   IL_0027
    IL_001b:  ldarg.0
    IL_001c:  ldarg.0
    IL_001d:  ldfld      ""T Program.<Shift2>d__2<T>.item""
    IL_0022:  stfld      ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0027:  ldarg.0
    IL_0028:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_002d:  call       ""System.Range Program.GetOffset<T>(ref T)""
    IL_0032:  call       ""System.Threading.Tasks.Task<System.Range> Program.GetOffsetAsync(System.Range)""
    IL_0037:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> System.Threading.Tasks.Task<System.Range>.GetAwaiter()""
    IL_003c:  stloc.s    V_6
    IL_003e:  ldloca.s   V_6
    IL_0040:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<System.Range>.IsCompleted.get""
    IL_0045:  brtrue.s   IL_0088
    IL_0047:  ldarg.0
    IL_0048:  ldc.i4.0
    IL_0049:  dup
    IL_004a:  stloc.0
    IL_004b:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0050:  ldarg.0
    IL_0051:  ldloc.s    V_6
    IL_0053:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift2>d__2<T>.<>u__1""
    IL_0058:  ldarg.0
    IL_0059:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_005e:  ldloca.s   V_6
    IL_0060:  ldarg.0
    IL_0061:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<System.Range>, Program.<Shift2>d__2<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<System.Range>, ref Program.<Shift2>d__2<T>)""
    IL_0066:  leave      IL_014a
    IL_006b:  ldarg.0
    IL_006c:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift2>d__2<T>.<>u__1""
    IL_0071:  stloc.s    V_6
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift2>d__2<T>.<>u__1""
    IL_0079:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<System.Range>""
    IL_007f:  ldarg.0
    IL_0080:  ldc.i4.m1
    IL_0081:  dup
    IL_0082:  stloc.0
    IL_0083:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0088:  ldloca.s   V_6
    IL_008a:  call       ""System.Range System.Runtime.CompilerServices.TaskAwaiter<System.Range>.GetResult()""
    IL_008f:  stloc.1
    IL_0090:  ldloca.s   V_5
    IL_0092:  initobj    ""T""
    IL_0098:  ldloc.s    V_5
    IL_009a:  box        ""T""
    IL_009f:  brtrue.s   IL_00a9
    IL_00a1:  ldarg.0
    IL_00a2:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00a7:  br.s       IL_00af
    IL_00a9:  ldarg.0
    IL_00aa:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_00af:  constrained. ""T""
    IL_00b5:  callvirt   ""int IMoveable.Length.get""
    IL_00ba:  stloc.2
    IL_00bb:  ldloca.s   V_1
    IL_00bd:  call       ""System.Index System.Range.Start.get""
    IL_00c2:  stloc.s    V_7
    IL_00c4:  ldloca.s   V_7
    IL_00c6:  ldloc.2
    IL_00c7:  call       ""int System.Index.GetOffset(int)""
    IL_00cc:  stloc.3
    IL_00cd:  ldloca.s   V_1
    IL_00cf:  call       ""System.Index System.Range.End.get""
    IL_00d4:  stloc.s    V_7
    IL_00d6:  ldloca.s   V_7
    IL_00d8:  ldloc.2
    IL_00d9:  call       ""int System.Index.GetOffset(int)""
    IL_00de:  ldloc.3
    IL_00df:  sub
    IL_00e0:  stloc.s    V_4
    IL_00e2:  ldloca.s   V_5
    IL_00e4:  initobj    ""T""
    IL_00ea:  ldloc.s    V_5
    IL_00ec:  box        ""T""
    IL_00f1:  brtrue.s   IL_00fb
    IL_00f3:  ldarg.0
    IL_00f4:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_00f9:  br.s       IL_0101
    IL_00fb:  ldarg.0
    IL_00fc:  ldflda     ""T Program.<Shift2>d__2<T>.item""
    IL_0101:  ldloc.3
    IL_0102:  ldloc.s    V_4
    IL_0104:  constrained. ""T""
    IL_010a:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
    IL_010f:  pop
    IL_0110:  ldarg.0
    IL_0111:  ldflda     ""T Program.<Shift2>d__2<T>.<>7__wrap1""
    IL_0116:  initobj    ""T""
    IL_011c:  leave.s    IL_0137
  }
  catch System.Exception
  {
    IL_011e:  stloc.s    V_8
    IL_0120:  ldarg.0
    IL_0121:  ldc.i4.s   -2
    IL_0123:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
    IL_0128:  ldarg.0
    IL_0129:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
    IL_012e:  ldloc.s    V_8
    IL_0130:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_0135:  leave.s    IL_014a
  }
  IL_0137:  ldarg.0
  IL_0138:  ldc.i4.s   -2
  IL_013a:  stfld      ""int Program.<Shift2>d__2<T>.<>1__state""
  IL_013f:  ldarg.0
  IL_0140:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift2>d__2<T>.<>t__builder""
  IL_0145:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_014a:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        [WorkItem(63221, "https://github.com/dotnet/roslyn/issues/63221")]
        public void GenericTypeParameterAsReceiver_ImplicitRangeIndexer_RangeValue_Struct_Async_01()
        {
            var source = @"
using System;
using System.Threading.Tasks;

interface IMoveable
{
    IMoveable Slice(int start, int length);
    int Length {get;}
}

struct Item : IMoveable
{
    public string Name {get; set;}

    public IMoveable Slice(int start, int length)
    {
        Console.WriteLine(""Position Slice for item '{0}'"", Name);
        return this;
    }

    public int Length
    {
        get
        {
            Console.WriteLine(""Position Length for item '{0}'"", Name);
            return 10;
        }
    }
}

class Program
{
    static async Task Main()
    {
        var item1 = new Item {Name = ""1""};
        await Shift1(item1);

        var item2 = new Item {Name = ""2""};
        await Shift2(item2);
    }

    static async Task Shift1<T>(T item) where T : struct, IMoveable
    {
        _ = item[await GetOffsetAsync(GetOffset(ref item))];
    }

    static async Task Shift2<T>(T item) where T : IMoveable
    {
        _ = item[await GetOffsetAsync(GetOffset(ref item))];
    }
    
    static int value = 0;
    static Range GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0..1;
    }

    static async Task<Range> GetOffsetAsync(Range i)
    {
        await Task.Yield();
        return i;
    }
}
";

            var expectedOutput = @"
Position Length for item '-1'
Position Slice for item '-1'
Position Length for item '-2'
Position Slice for item '-2'
";
            var verifier = CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Shift1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      240 (0xf0)
  .maxstack  3
  .locals init (int V_0,
                System.Range V_1,
                int V_2,
                int V_3,
                int V_4,
                System.Runtime.CompilerServices.TaskAwaiter<System.Range> V_5,
                System.Index V_6,
                System.Exception V_7)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_004e
    IL_000a:  ldarg.0
    IL_000b:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0010:  call       ""System.Range Program.GetOffset<T>(ref T)""
    IL_0015:  call       ""System.Threading.Tasks.Task<System.Range> Program.GetOffsetAsync(System.Range)""
    IL_001a:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> System.Threading.Tasks.Task<System.Range>.GetAwaiter()""
    IL_001f:  stloc.s    V_5
    IL_0021:  ldloca.s   V_5
    IL_0023:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<System.Range>.IsCompleted.get""
    IL_0028:  brtrue.s   IL_006b
    IL_002a:  ldarg.0
    IL_002b:  ldc.i4.0
    IL_002c:  dup
    IL_002d:  stloc.0
    IL_002e:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_0033:  ldarg.0
    IL_0034:  ldloc.s    V_5
    IL_0036:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift1>d__1<T>.<>u__1""
    IL_003b:  ldarg.0
    IL_003c:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_0041:  ldloca.s   V_5
    IL_0043:  ldarg.0
    IL_0044:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<System.Range>, Program.<Shift1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<System.Range>, ref Program.<Shift1>d__1<T>)""
    IL_0049:  leave      IL_00ef
    IL_004e:  ldarg.0
    IL_004f:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift1>d__1<T>.<>u__1""
    IL_0054:  stloc.s    V_5
    IL_0056:  ldarg.0
    IL_0057:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<System.Range> Program.<Shift1>d__1<T>.<>u__1""
    IL_005c:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<System.Range>""
    IL_0062:  ldarg.0
    IL_0063:  ldc.i4.m1
    IL_0064:  dup
    IL_0065:  stloc.0
    IL_0066:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_006b:  ldloca.s   V_5
    IL_006d:  call       ""System.Range System.Runtime.CompilerServices.TaskAwaiter<System.Range>.GetResult()""
    IL_0072:  stloc.1
    IL_0073:  ldarg.0
    IL_0074:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_0079:  constrained. ""T""
    IL_007f:  callvirt   ""int IMoveable.Length.get""
    IL_0084:  stloc.2
    IL_0085:  ldloca.s   V_1
    IL_0087:  call       ""System.Index System.Range.Start.get""
    IL_008c:  stloc.s    V_6
    IL_008e:  ldloca.s   V_6
    IL_0090:  ldloc.2
    IL_0091:  call       ""int System.Index.GetOffset(int)""
    IL_0096:  stloc.3
    IL_0097:  ldloca.s   V_1
    IL_0099:  call       ""System.Index System.Range.End.get""
    IL_009e:  stloc.s    V_6
    IL_00a0:  ldloca.s   V_6
    IL_00a2:  ldloc.2
    IL_00a3:  call       ""int System.Index.GetOffset(int)""
    IL_00a8:  ldloc.3
    IL_00a9:  sub
    IL_00aa:  stloc.s    V_4
    IL_00ac:  ldarg.0
    IL_00ad:  ldflda     ""T Program.<Shift1>d__1<T>.item""
    IL_00b2:  ldloc.3
    IL_00b3:  ldloc.s    V_4
    IL_00b5:  constrained. ""T""
    IL_00bb:  callvirt   ""IMoveable IMoveable.Slice(int, int)""
    IL_00c0:  pop
    IL_00c1:  leave.s    IL_00dc
  }
  catch System.Exception
  {
    IL_00c3:  stloc.s    V_7
    IL_00c5:  ldarg.0
    IL_00c6:  ldc.i4.s   -2
    IL_00c8:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
    IL_00cd:  ldarg.0
    IL_00ce:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
    IL_00d3:  ldloc.s    V_7
    IL_00d5:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00da:  leave.s    IL_00ef
  }
  IL_00dc:  ldarg.0
  IL_00dd:  ldc.i4.s   -2
  IL_00df:  stfld      ""int Program.<Shift1>d__1<T>.<>1__state""
  IL_00e4:  ldarg.0
  IL_00e5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Shift1>d__1<T>.<>t__builder""
  IL_00ea:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00ef:  ret
}
");

            CompileAndVerify(source, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        [WorkItem(66162, "https://github.com/dotnet/roslyn/issues/66162")]
        public void GenericTypeParameterAsReceiver_Call_Nullable()
        {
            var source = @"
using System;

#pragma warning disable CS0659 // 'Item' overrides Object.Equals(object o) but does not override Object.GetHashCode()
    
struct Item
{
    public int Count;

    public override bool Equals(object obj)
    {
        Console.WriteLine(""Position Equals for item '{0}'"", Count);
        return base.Equals(obj);
    }
}

class Program
{
    static void Main()
    {
        Item? item1 = new Item {Count = 1};
        Call1(item1);
        Item? item2 = new Item {Count = 2};
        Call2(ref item2);
    }

    static void Call1<T>(T item)
    {
        item.Equals(GetOffset(ref item));
    }

    static void Call2<T>(ref T item)
    {
        item.Equals(GetOffset(ref item));
    }
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(object)new Item {Count = --value};
        return 0;
    }
}
";
            // The output doesn't match the expectation, see https://github.com/dotnet/roslyn/issues/66162
            var expectedOutput = @"
Position Equals for item '1'
Position Equals for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
  // Code size       51 (0x33)
  .maxstack  2
  .locals init (T V_0)
  IL_0000:  ldarga.s   V_0
  IL_0002:  ldloca.s   V_0
  IL_0004:  initobj    ""T""
  IL_000a:  ldloc.0
  IL_000b:  box        ""T""
  IL_0010:  brtrue.s   IL_001a
  IL_0012:  ldobj      ""T""
  IL_0017:  stloc.0
  IL_0018:  ldloca.s   V_0
  IL_001a:  ldarga.s   V_0
  IL_001c:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0021:  box        ""int""
  IL_0026:  constrained. ""T""
  IL_002c:  callvirt   ""bool object.Equals(object)""
  IL_0031:  pop
  IL_0032:  ret
}
");

            verifier.VerifyIL("Program.Call2<T>",
@"
{
  // Code size       49 (0x31)
  .maxstack  2
  .locals init (T V_0)
  IL_0000:  ldarg.0
  IL_0001:  ldloca.s   V_0
  IL_0003:  initobj    ""T""
  IL_0009:  ldloc.0
  IL_000a:  box        ""T""
  IL_000f:  brtrue.s   IL_0019
  IL_0011:  ldobj      ""T""
  IL_0016:  stloc.0
  IL_0017:  ldloca.s   V_0
  IL_0019:  ldarg.0
  IL_001a:  call       ""int Program.GetOffset<T>(ref T)""
  IL_001f:  box        ""int""
  IL_0024:  constrained. ""T""
  IL_002a:  callvirt   ""bool object.Equals(object)""
  IL_002f:  pop
  IL_0030:  ret
}
");
        }

        [Fact]
        [WorkItem(66162, "https://github.com/dotnet/roslyn/issues/66162")]
        public void GenericTypeParameterAsReceiver_Call_Nullable_Async()
        {
            var source = @"
using System;
using System.Threading.Tasks;

#pragma warning disable CS0659 // 'Item' overrides Object.Equals(object o) but does not override Object.GetHashCode()
    
struct Item
{
    public int Count;

    public override bool Equals(object obj)
    {
        Console.WriteLine(""Position Equals for item '{0}'"", Count);
        return base.Equals(obj);
    }
}

class Program
{
    static async Task Main()
    {
        Item? item1 = new Item {Count = 1};
        await Call1(item1);
    }

    static async Task Call1<T>(T item)
    {
        item.Equals(await GetOffsetAsync(GetOffset(ref item)));
    }

    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(object)new Item {Count = --value};
        return 0;
    }

    static async Task<int> GetOffsetAsync(int i)
    {
        await Task.Yield();
        return i;
    }
}
";

            // The output doesn't match the expectation, see https://github.com/dotnet/roslyn/issues/66162
            var expectedOutput = @"
Position Equals for item '1'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.<Call1>d__1<T>.System.Runtime.CompilerServices.IAsyncStateMachine.MoveNext",
@"
{
  // Code size      247 (0xf7)
  .maxstack  3
  .locals init (int V_0,
                int V_1,
                T V_2,
                System.Runtime.CompilerServices.TaskAwaiter<int> V_3,
                System.Exception V_4)
  IL_0000:  ldarg.0
  IL_0001:  ldfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_0006:  stloc.0
  .try
  {
    IL_0007:  ldloc.0
    IL_0008:  brfalse.s  IL_0068
    IL_000a:  ldloca.s   V_2
    IL_000c:  initobj    ""T""
    IL_0012:  ldloc.2
    IL_0013:  box        ""T""
    IL_0018:  brtrue.s   IL_0026
    IL_001a:  ldarg.0
    IL_001b:  ldarg.0
    IL_001c:  ldfld      ""T Program.<Call1>d__1<T>.item""
    IL_0021:  stfld      ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_0026:  ldarg.0
    IL_0027:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_002c:  call       ""int Program.GetOffset<T>(ref T)""
    IL_0031:  call       ""System.Threading.Tasks.Task<int> Program.GetOffsetAsync(int)""
    IL_0036:  callvirt   ""System.Runtime.CompilerServices.TaskAwaiter<int> System.Threading.Tasks.Task<int>.GetAwaiter()""
    IL_003b:  stloc.3
    IL_003c:  ldloca.s   V_3
    IL_003e:  call       ""bool System.Runtime.CompilerServices.TaskAwaiter<int>.IsCompleted.get""
    IL_0043:  brtrue.s   IL_0084
    IL_0045:  ldarg.0
    IL_0046:  ldc.i4.0
    IL_0047:  dup
    IL_0048:  stloc.0
    IL_0049:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_004e:  ldarg.0
    IL_004f:  ldloc.3
    IL_0050:  stfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0055:  ldarg.0
    IL_0056:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_005b:  ldloca.s   V_3
    IL_005d:  ldarg.0
    IL_005e:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.AwaitUnsafeOnCompleted<System.Runtime.CompilerServices.TaskAwaiter<int>, Program.<Call1>d__1<T>>(ref System.Runtime.CompilerServices.TaskAwaiter<int>, ref Program.<Call1>d__1<T>)""
    IL_0063:  leave      IL_00f6
    IL_0068:  ldarg.0
    IL_0069:  ldfld      ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_006e:  stloc.3
    IL_006f:  ldarg.0
    IL_0070:  ldflda     ""System.Runtime.CompilerServices.TaskAwaiter<int> Program.<Call1>d__1<T>.<>u__1""
    IL_0075:  initobj    ""System.Runtime.CompilerServices.TaskAwaiter<int>""
    IL_007b:  ldarg.0
    IL_007c:  ldc.i4.m1
    IL_007d:  dup
    IL_007e:  stloc.0
    IL_007f:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_0084:  ldloca.s   V_3
    IL_0086:  call       ""int System.Runtime.CompilerServices.TaskAwaiter<int>.GetResult()""
    IL_008b:  stloc.1
    IL_008c:  ldloca.s   V_2
    IL_008e:  initobj    ""T""
    IL_0094:  ldloc.2
    IL_0095:  box        ""T""
    IL_009a:  brtrue.s   IL_00a4
    IL_009c:  ldarg.0
    IL_009d:  ldflda     ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_00a2:  br.s       IL_00aa
    IL_00a4:  ldarg.0
    IL_00a5:  ldflda     ""T Program.<Call1>d__1<T>.item""
    IL_00aa:  ldloc.1
    IL_00ab:  box        ""int""
    IL_00b0:  constrained. ""T""
    IL_00b6:  callvirt   ""bool object.Equals(object)""
    IL_00bb:  pop
    IL_00bc:  ldarg.0
    IL_00bd:  ldflda     ""T Program.<Call1>d__1<T>.<>7__wrap1""
    IL_00c2:  initobj    ""T""
    IL_00c8:  leave.s    IL_00e3
  }
  catch System.Exception
  {
    IL_00ca:  stloc.s    V_4
    IL_00cc:  ldarg.0
    IL_00cd:  ldc.i4.s   -2
    IL_00cf:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
    IL_00d4:  ldarg.0
    IL_00d5:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
    IL_00da:  ldloc.s    V_4
    IL_00dc:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetException(System.Exception)""
    IL_00e1:  leave.s    IL_00f6
  }
  IL_00e3:  ldarg.0
  IL_00e4:  ldc.i4.s   -2
  IL_00e6:  stfld      ""int Program.<Call1>d__1<T>.<>1__state""
  IL_00eb:  ldarg.0
  IL_00ec:  ldflda     ""System.Runtime.CompilerServices.AsyncTaskMethodBuilder Program.<Call1>d__1<T>.<>t__builder""
  IL_00f1:  call       ""void System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()""
  IL_00f6:  ret
}
");

            CompileAndVerify(source, options: TestOptions.DebugExe, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        public void ChainedCalls()
        {
            var source = @"
using System;

interface IMoveable
{
    void GetName(int x);
}

class Item : IMoveable
{
    public string Name {get; set;}

    public void GetName(int x)
    {
        Console.WriteLine(""Position GetName for item '{0}'"", Name);
    }
}

class Program
{
    static void Main()
    {
        var item1 = new Item {Name = ""1""};
        Call1(new Program(), item1);

        var item2 = new Item {Name = ""2""};
        Call2(new Program(), item2);
    }

    static void Call1<T>(Program p, T item) where T : class, IMoveable
    {
        p.GetReceiver(ref item).GetName(GetOffset(ref item));
    }

    static void Call2<T>(Program p, T item) where T : IMoveable
    {
        p.GetReceiver(ref item).GetName(GetOffset(ref item));
    }

    ref T GetReceiver<T>(ref T x) => ref x;
    
    static int value = 0;
    static int GetOffset<T>(ref T item)
    {
        item = (T)(IMoveable)new Item {Name = (--value).ToString()};
        return 0;
    }
}
";

            var expectedOutput = @"
Position GetName for item '1'
Position GetName for item '2'
";
            var verifier = CompileAndVerify(source, options: TestOptions.ReleaseExe, verify: Verification.Fails, expectedOutput: expectedOutput).VerifyDiagnostics();

            verifier.VerifyIL("Program.Call1<T>",
@"
{
      // Code size       31 (0x1f)
  .maxstack  2
  IL_0000:  ldarg.0
  IL_0001:  ldarga.s   V_1
  IL_0003:  callvirt   ""ref T Program.GetReceiver<T>(ref T)""
  IL_0008:  ldobj      ""T""
  IL_000d:  box        ""T""
  IL_0012:  ldarga.s   V_1
  IL_0014:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0019:  callvirt   ""void IMoveable.GetName(int)""
  IL_001e:  ret
}
");

            verifier.VerifyIL("Program.Call2<T>",
@"
{
  // Code size       51 (0x33)
  .maxstack  2
  .locals init (T V_0)
  IL_0000:  ldarg.0
  IL_0001:  ldarga.s   V_1
  IL_0003:  callvirt   ""ref T Program.GetReceiver<T>(ref T)""
  IL_0008:  ldloca.s   V_0
  IL_000a:  initobj    ""T""
  IL_0010:  ldloc.0
  IL_0011:  box        ""T""
  IL_0016:  brtrue.s   IL_0020
  IL_0018:  ldobj      ""T""
  IL_001d:  stloc.0
  IL_001e:  ldloca.s   V_0
  IL_0020:  ldarga.s   V_1
  IL_0022:  call       ""int Program.GetOffset<T>(ref T)""
  IL_0027:  constrained. ""T""
  IL_002d:  callvirt   ""void IMoveable.GetName(int)""
  IL_0032:  ret
}
");
            CompileAndVerify(source, options: TestOptions.DebugExe, verify: Verification.Fails, expectedOutput: expectedOutput).VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_PropertyAccess_PrefixIncrementAssignment_01()
        {
            var src = """
interface I1
{
    public int P1 {get; set;}
}

struct S1 : I1
{
    public int F1;

    public int P1
    {
        get
        {
            System.Console.Write(F1);
            Program.F.F1++;
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static S1 F;

    static void Main()
    {
        F = new S1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        ++f.P1;
    }

    static void Test2<T>(ref T f) where T : struct, I1
    {
        ++f.P1;
    }

    static void Test3(ref S1 f)
    {
        ++f.P1;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123124124:123124124:123124124").VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_PropertyAccess_PrefixIncrementAssignment_02()
        {
            var src = """
interface I1
{
    public int P1 {get; set;}
}

class C1 : I1
{
    public int F1;

    public int P1
    {
        get
        {
            System.Console.Write(F1);
            Program.F = new C1 { F1 = Program.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static C1 F;

    static void Main()
    {
        F = new C1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        ++f.P1;
    }

    static void Test2<T>(ref T f) where T : class, I1
    {
        ++f.P1;
    }

    static void Test3(ref C1 f)
    {
        ++f.P1;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            var verifier = CompileAndVerify(comp, expectedOutput: "123123124:123123124:123123124").VerifyDiagnostics();

            verifier.VerifyIL("Program.Test1<T>(ref T)",
@"
{
  // Code size       60 (0x3c)
  .maxstack  3
  .locals init (T V_0,
                T& V_1,
                int V_2,
                T V_3)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  stloc.1
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.1
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.0
  IL_001a:  ldloca.s   V_0
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.1
  IL_001f:  dup
  IL_0020:  constrained. ""T""
  IL_0026:  callvirt   ""int I1.P1.get""
  IL_002b:  ldc.i4.1
  IL_002c:  add
  IL_002d:  stloc.2
  IL_002e:  ldloc.2
  IL_002f:  constrained. ""T""
  IL_0035:  callvirt   ""void I1.P1.set""
  IL_003a:  nop
  IL_003b:  ret
}
");

            verifier.VerifyIL("Program.Test2<T>(ref T)",
@"
{
  // Code size       39 (0x27)
  .maxstack  3
  .locals init (T V_0,
                int V_1)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  ldobj      ""T""
  IL_0007:  stloc.0
  IL_0008:  ldloca.s   V_0
  IL_000a:  dup
  IL_000b:  constrained. ""T""
  IL_0011:  callvirt   ""int I1.P1.get""
  IL_0016:  ldc.i4.1
  IL_0017:  add
  IL_0018:  stloc.1
  IL_0019:  ldloc.1
  IL_001a:  constrained. ""T""
  IL_0020:  callvirt   ""void I1.P1.set""
  IL_0025:  nop
  IL_0026:  ret
}
");
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_PropertyAccess_PostfixIncrementAssignment_01()
        {
            var src = """
interface I1
{
    public int P1 {get; set;}
}

struct S1 : I1
{
    public int F1;

    public int P1
    {
        get
        {
            System.Console.Write(F1);
            Program.F.F1++;
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static S1 F;

    static void Main()
    {
        F = new S1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f.P1++;
    }

    static void Test2<T>(ref T f) where T : struct, I1
    {
        f.P1++;
    }

    static void Test3(ref S1 f)
    {
        f.P1++;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123124124:123124124:123124124").VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_PropertyAccess_PostfixIncrementAssignment_02()
        {
            var src = """
interface I1
{
    public int P1 {get; set;}
}

class C1 : I1
{
    public int F1;

    public int P1
    {
        get
        {
            System.Console.Write(F1);
            Program.F = new C1 { F1 = Program.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static C1 F;

    static void Main()
    {
        F = new C1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f.P1++;
    }

    static void Test2<T>(ref T f) where T : class, I1
    {
        f.P1++;
    }

    static void Test3(ref C1 f)
    {
        f.P1++;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            var verifier = CompileAndVerify(comp, expectedOutput: "123123124:123123124:123123124").VerifyDiagnostics();

            verifier.VerifyIL("Program.Test1<T>(ref T)",
@"
{
  // Code size       60 (0x3c)
  .maxstack  3
  .locals init (T V_0,
                T& V_1,
                int V_2,
                T V_3)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  stloc.1
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.1
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.0
  IL_001a:  ldloca.s   V_0
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.1
  IL_001f:  dup
  IL_0020:  constrained. ""T""
  IL_0026:  callvirt   ""int I1.P1.get""
  IL_002b:  stloc.2
  IL_002c:  ldloc.2
  IL_002d:  ldc.i4.1
  IL_002e:  add
  IL_002f:  constrained. ""T""
  IL_0035:  callvirt   ""void I1.P1.set""
  IL_003a:  nop
  IL_003b:  ret
}
");

            verifier.VerifyIL("Program.Test2<T>(ref T)",
@"
{
  // Code size       39 (0x27)
  .maxstack  3
  .locals init (T V_0,
            int V_1)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  ldobj      ""T""
  IL_0007:  stloc.0
  IL_0008:  ldloca.s   V_0
  IL_000a:  dup
  IL_000b:  constrained. ""T""
  IL_0011:  callvirt   ""int I1.P1.get""
  IL_0016:  stloc.1
  IL_0017:  ldloc.1
  IL_0018:  ldc.i4.1
  IL_0019:  add
  IL_001a:  constrained. ""T""
  IL_0020:  callvirt   ""void I1.P1.set""
  IL_0025:  nop
  IL_0026:  ret
}
");
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_PrefixIncrementAssignment_01()
        {
            var src = """
interface I1
{
    public int this[int x] {get; set;}
}

struct S1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program.F.F1++;
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static S1 F;

    static void Main()
    {
        F = new S1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        ++f[0];
    }

    static void Test2<T>(ref T f) where T : struct, I1
    {
        ++f[0];
    }

    static void Test3(ref S1 f)
    {
        ++f[0];
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123124124:123124124:123124124").VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_PrefixIncrementAssignment_02()
        {
            var src = """
interface I1
{
    public int this[int x] {get; set;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program.F = new C1 { F1 = Program.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static C1 F;

    static void Main()
    {
        F = new C1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        ++f[0];
    }

    static void Test2<T>(ref T f) where T : class, I1
    {
        ++f[0];
    }

    static void Test3(ref C1 f)
    {
        ++f[0];
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            var verifier = CompileAndVerify(comp, expectedOutput: "123123124:123123124:123123124").VerifyDiagnostics();

            verifier.VerifyIL("Program.Test1<T>(ref T)",
@"
{
  // Code size       62 (0x3e)
  .maxstack  3
  .locals init (T V_0,
                T& V_1,
                int V_2,
                T V_3)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  stloc.1
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.1
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.0
  IL_001a:  ldloca.s   V_0
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.1
  IL_001f:  dup
  IL_0020:  ldc.i4.0
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""int I1.this[int].get""
  IL_002c:  ldc.i4.1
  IL_002d:  add
  IL_002e:  stloc.2
  IL_002f:  ldc.i4.0
  IL_0030:  ldloc.2
  IL_0031:  constrained. ""T""
  IL_0037:  callvirt   ""void I1.this[int].set""
  IL_003c:  nop
  IL_003d:  ret
}
");

            verifier.VerifyIL("Program.Test2<T>(ref T)",
@"
{
  // Code size       41 (0x29)
  .maxstack  3
  .locals init (T V_0,
            int V_1)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  ldobj      ""T""
  IL_0007:  stloc.0
  IL_0008:  ldloca.s   V_0
  IL_000a:  dup
  IL_000b:  ldc.i4.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int I1.this[int].get""
  IL_0017:  ldc.i4.1
  IL_0018:  add
  IL_0019:  stloc.1
  IL_001a:  ldc.i4.0
  IL_001b:  ldloc.1
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""void I1.this[int].set""
  IL_0027:  nop
  IL_0028:  ret
}
");
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_PrefixIncrementAssignment_03()
        {
            var src = """
using System.Threading.Tasks;

interface I1
{
    public int this[int x] {get; set;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program<T>
{
    public static T F;
}

class Program
{
    static async Task Main()
    {
        Program<C1>.F = new C1 { F1 = 123 };
        await Test1<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test2<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test3();
        System.Console.Write(Program<C1>.F.F1);
    }

    static async Task Test1<T>() where T : I1
    {
        ++Program<T>.F[await Get0()];
    }

    static async Task Test2<T>() where T : class, I1
    {
        ++Program<T>.F[await Get0()];
    }

    static async Task Test3()
    {
        ++Program<C1>.F[await Get0()];
    }

    static async Task<int> Get0()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 0;
    }
}
""";

            var expectedOutput = "123123125:123123125:123123125";
            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();

            comp = CreateRuntimeAsyncCompilation(src, options: TestOptions.ReleaseExe);
            var verifier = CompileAndVerify(comp, expectedOutput: RuntimeAsyncTestHelpers.ExpectedOutput(expectedOutput), verify: Verification.Fails with
            {
                ILVerifyMessage = """
                    [Main]: Return value missing on the stack. { Offset = 0x95 }
                    [Test1]: Return value missing on the stack. { Offset = 0x77 }
                    [Test2]: Return value missing on the stack. { Offset = 0x2b }
                    [Test3]: Return value missing on the stack. { Offset = 0x21 }
                    [Get0]: Unexpected type on the stack. { Offset = 0x41, Found = Int32, Expected = ref '[System.Runtime]System.Threading.Tasks.Task`1<int32>' }
                    """
            });

            verifier.VerifyIL("Program.Test1<T>()", """
                {
                  // Code size      120 (0x78)
                  .maxstack  3
                  .locals init (T V_0,
                                int V_1,
                                int V_2,
                                T V_3)
                  IL_0000:  ldloca.s   V_3
                  IL_0002:  initobj    "T"
                  IL_0008:  ldloc.3
                  IL_0009:  box        "T"
                  IL_000e:  brtrue.s   IL_0018
                  IL_0010:  ldsfld     "T Program<T>.F"
                  IL_0015:  stloc.0
                  IL_0016:  br.s       IL_001e
                  IL_0018:  ldsfld     "T Program<T>.F"
                  IL_001d:  pop
                  IL_001e:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_0023:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0028:  stloc.1
                  IL_0029:  ldloca.s   V_3
                  IL_002b:  initobj    "T"
                  IL_0031:  ldloc.3
                  IL_0032:  box        "T"
                  IL_0037:  brtrue.s   IL_003d
                  IL_0039:  ldloca.s   V_0
                  IL_003b:  br.s       IL_0042
                  IL_003d:  ldsflda    "T Program<T>.F"
                  IL_0042:  ldloc.1
                  IL_0043:  constrained. "T"
                  IL_0049:  callvirt   "int I1.this[int].get"
                  IL_004e:  ldc.i4.1
                  IL_004f:  add
                  IL_0050:  stloc.2
                  IL_0051:  ldloca.s   V_3
                  IL_0053:  initobj    "T"
                  IL_0059:  ldloc.3
                  IL_005a:  box        "T"
                  IL_005f:  brtrue.s   IL_0065
                  IL_0061:  ldloca.s   V_0
                  IL_0063:  br.s       IL_006a
                  IL_0065:  ldsflda    "T Program<T>.F"
                  IL_006a:  ldloc.1
                  IL_006b:  ldloc.2
                  IL_006c:  constrained. "T"
                  IL_0072:  callvirt   "void I1.this[int].set"
                  IL_0077:  ret
                }
                """);
            verifier.VerifyIL("Program.Test2<T>()", """
                {
                  // Code size       44 (0x2c)
                  .maxstack  3
                  .locals init (int V_0,
                                int V_1)
                  IL_0000:  ldsfld     "T Program<T>.F"
                  IL_0005:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000a:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_000f:  stloc.0
                  IL_0010:  dup
                  IL_0011:  box        "T"
                  IL_0016:  ldloc.0
                  IL_0017:  callvirt   "int I1.this[int].get"
                  IL_001c:  ldc.i4.1
                  IL_001d:  add
                  IL_001e:  stloc.1
                  IL_001f:  box        "T"
                  IL_0024:  ldloc.0
                  IL_0025:  ldloc.1
                  IL_0026:  callvirt   "void I1.this[int].set"
                  IL_002b:  ret
                }
                """);
            verifier.VerifyIL("Program.Test3()", """
                {
                  // Code size       34 (0x22)
                  .maxstack  3
                  .locals init (int V_0,
                                int V_1)
                  IL_0000:  ldsfld     "C1 Program<C1>.F"
                  IL_0005:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000a:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_000f:  stloc.0
                  IL_0010:  dup
                  IL_0011:  ldloc.0
                  IL_0012:  callvirt   "int C1.this[int].get"
                  IL_0017:  ldc.i4.1
                  IL_0018:  add
                  IL_0019:  stloc.1
                  IL_001a:  ldloc.0
                  IL_001b:  ldloc.1
                  IL_001c:  callvirt   "void C1.this[int].set"
                  IL_0021:  ret
                }
                """);
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_PostfixIncrementAssignment_01()
        {
            var src = """
interface I1
{
    public int this[int x] {get; set;}
}

struct S1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program.F.F1++;
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static S1 F;

    static void Main()
    {
        F = new S1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f[0]++;
    }

    static void Test2<T>(ref T f) where T : struct, I1
    {
        f[0]++;
    }

    static void Test3(ref S1 f)
    {
        f[0]++;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123124124:123124124:123124124").VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_PostfixIncrementAssignment_02()
        {
            var src = """
interface I1
{
    public int this[int x] {get; set;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program.F = new C1 { F1 = Program.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static C1 F;

    static void Main()
    {
        F = new C1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f[0]++;
    }

    static void Test2<T>(ref T f) where T : class, I1
    {
        f[0]++;
    }

    static void Test3(ref C1 f)
    {
        f[0]++;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            var verifier = CompileAndVerify(comp, expectedOutput: "123123124:123123124:123123124").VerifyDiagnostics();

            verifier.VerifyIL("Program.Test1<T>(ref T)",
@"
{
  // Code size       62 (0x3e)
  .maxstack  4
  .locals init (T V_0,
            T& V_1,
            int V_2,
            T V_3)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  stloc.1
  IL_0003:  ldloca.s   V_3
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.3
  IL_000c:  box        ""T""
  IL_0011:  brtrue.s   IL_001e
  IL_0013:  ldloc.1
  IL_0014:  ldobj      ""T""
  IL_0019:  stloc.0
  IL_001a:  ldloca.s   V_0
  IL_001c:  br.s       IL_001f
  IL_001e:  ldloc.1
  IL_001f:  dup
  IL_0020:  ldc.i4.0
  IL_0021:  constrained. ""T""
  IL_0027:  callvirt   ""int I1.this[int].get""
  IL_002c:  stloc.2
  IL_002d:  ldc.i4.0
  IL_002e:  ldloc.2
  IL_002f:  ldc.i4.1
  IL_0030:  add
  IL_0031:  constrained. ""T""
  IL_0037:  callvirt   ""void I1.this[int].set""
  IL_003c:  nop
  IL_003d:  ret
}
");

            verifier.VerifyIL("Program.Test2<T>(ref T)",
@"
{
  // Code size       41 (0x29)
  .maxstack  4
  .locals init (T V_0,
                int V_1)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  ldobj      ""T""
  IL_0007:  stloc.0
  IL_0008:  ldloca.s   V_0
  IL_000a:  dup
  IL_000b:  ldc.i4.0
  IL_000c:  constrained. ""T""
  IL_0012:  callvirt   ""int I1.this[int].get""
  IL_0017:  stloc.1
  IL_0018:  ldc.i4.0
  IL_0019:  ldloc.1
  IL_001a:  ldc.i4.1
  IL_001b:  add
  IL_001c:  constrained. ""T""
  IL_0022:  callvirt   ""void I1.this[int].set""
  IL_0027:  nop
  IL_0028:  ret
}
");
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_PostfixIncrementAssignment_03()
        {
            var src = """
using System.Threading.Tasks;

interface I1
{
    public int this[int x] {get; set;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program<T>
{
    public static T F;
}

class Program
{
    static async Task Main()
    {
        Program<C1>.F = new C1 { F1 = 123 };
        await Test1<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test2<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test3();
        System.Console.Write(Program<C1>.F.F1);
    }

    static async Task Test1<T>() where T : I1
    {
        Program<T>.F[await Get0()]++;
    }

    static async Task Test2<T>() where T : class, I1
    {
        Program<T>.F[await Get0()]++;
    }

    static async Task Test3()
    {
        Program<C1>.F[await Get0()]++;
    }

    static async Task<int> Get0()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 0;
    }
}
""";

            var expectedOutput = "123123125:123123125:123123125";
            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();

            comp = CreateRuntimeAsyncCompilation(src, options: TestOptions.ReleaseExe);
            var verifier = CompileAndVerify(comp, expectedOutput: RuntimeAsyncTestHelpers.ExpectedOutput(expectedOutput), verify: Verification.Fails with
            {
                ILVerifyMessage = """
                    [Main]: Return value missing on the stack. { Offset = 0x95 }
                    [Test1]: Return value missing on the stack. { Offset = 0x77 }
                    [Test2]: Return value missing on the stack. { Offset = 0x2b }
                    [Test3]: Return value missing on the stack. { Offset = 0x21 }
                    [Get0]: Unexpected type on the stack. { Offset = 0x41, Found = Int32, Expected = ref '[System.Runtime]System.Threading.Tasks.Task`1<int32>' }
                    """
            });

            verifier.VerifyIL("Program.Test1<T>()", """
                {
                  // Code size      120 (0x78)
                  .maxstack  4
                  .locals init (T V_0,
                                int V_1,
                                int V_2,
                                T V_3)
                  IL_0000:  ldloca.s   V_3
                  IL_0002:  initobj    "T"
                  IL_0008:  ldloc.3
                  IL_0009:  box        "T"
                  IL_000e:  brtrue.s   IL_0018
                  IL_0010:  ldsfld     "T Program<T>.F"
                  IL_0015:  stloc.0
                  IL_0016:  br.s       IL_001e
                  IL_0018:  ldsfld     "T Program<T>.F"
                  IL_001d:  pop
                  IL_001e:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_0023:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0028:  stloc.1
                  IL_0029:  ldloca.s   V_3
                  IL_002b:  initobj    "T"
                  IL_0031:  ldloc.3
                  IL_0032:  box        "T"
                  IL_0037:  brtrue.s   IL_003d
                  IL_0039:  ldloca.s   V_0
                  IL_003b:  br.s       IL_0042
                  IL_003d:  ldsflda    "T Program<T>.F"
                  IL_0042:  ldloc.1
                  IL_0043:  constrained. "T"
                  IL_0049:  callvirt   "int I1.this[int].get"
                  IL_004e:  stloc.2
                  IL_004f:  ldloca.s   V_3
                  IL_0051:  initobj    "T"
                  IL_0057:  ldloc.3
                  IL_0058:  box        "T"
                  IL_005d:  brtrue.s   IL_0063
                  IL_005f:  ldloca.s   V_0
                  IL_0061:  br.s       IL_0068
                  IL_0063:  ldsflda    "T Program<T>.F"
                  IL_0068:  ldloc.1
                  IL_0069:  ldloc.2
                  IL_006a:  ldc.i4.1
                  IL_006b:  add
                  IL_006c:  constrained. "T"
                  IL_0072:  callvirt   "void I1.this[int].set"
                  IL_0077:  ret
                }
                """);
            verifier.VerifyIL("Program.Test2<T>()", """
                {
                  // Code size       44 (0x2c)
                  .maxstack  4
                  .locals init (int V_0,
                                int V_1)
                  IL_0000:  ldsfld     "T Program<T>.F"
                  IL_0005:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000a:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_000f:  stloc.0
                  IL_0010:  dup
                  IL_0011:  box        "T"
                  IL_0016:  ldloc.0
                  IL_0017:  callvirt   "int I1.this[int].get"
                  IL_001c:  stloc.1
                  IL_001d:  box        "T"
                  IL_0022:  ldloc.0
                  IL_0023:  ldloc.1
                  IL_0024:  ldc.i4.1
                  IL_0025:  add
                  IL_0026:  callvirt   "void I1.this[int].set"
                  IL_002b:  ret
                }
                """);
            verifier.VerifyIL("Program.Test3()", """
                {
                  // Code size       34 (0x22)
                  .maxstack  4
                  .locals init (int V_0,
                                int V_1)
                  IL_0000:  ldsfld     "C1 Program<C1>.F"
                  IL_0005:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000a:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_000f:  stloc.0
                  IL_0010:  dup
                  IL_0011:  ldloc.0
                  IL_0012:  callvirt   "int C1.this[int].get"
                  IL_0017:  stloc.1
                  IL_0018:  ldloc.0
                  IL_0019:  ldloc.1
                  IL_001a:  ldc.i4.1
                  IL_001b:  add
                  IL_001c:  callvirt   "void C1.this[int].set"
                  IL_0021:  ret
                }
                """);
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_PropertyAccess_CompoundAssignment_01()
        {
            var src = """
interface I1
{
    public int P1 {get; set;}
}

struct S1 : I1
{
    public int F1;

    public int P1
    {
        get
        {
            System.Console.Write(F1);
            Program.F.F1++;
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static S1 F;

    static void Main()
    {
        F = new S1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f.P1 += 1;
    }

    static void Test2<T>(ref T f) where T : struct, I1
    {
        f.P1 += 1;
    }

    static void Test3(ref S1 f)
    {
        f.P1 += 1;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123124124:123124124:123124124").VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_PropertyAccess_CompoundAssignment_02()
        {
            var src = """
interface I1
{
    public int P1 {get; set;}
}

class C1 : I1
{
    public int F1;

    public int P1
    {
        get
        {
            System.Console.Write(F1);
            Program.F = new C1 { F1 = Program.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static C1 F;

    static void Main()
    {
        F = new C1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f.P1 += 1;
    }

    static void Test2<T>(ref T f) where T : class, I1
    {
        f.P1 += 1;
    }

    static void Test3(ref C1 f)
    {
        f.P1 += 1;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123123124:123123124:123123124").VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_CompoundAssignment_01()
        {
            var src = """
interface I1
{
    public int this[int x] {get; set;}
}

struct S1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program.F.F1++;
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static S1 F;

    static void Main()
    {
        F = new S1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f[0] += 1;
    }

    static void Test2<T>(ref T f) where T : struct, I1
    {
        f[0] += 1;
    }

    static void Test3(ref S1 f)
    {
        f[0] += 1;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123124124:123124124:123124124").VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_CompoundAssignment_02()
        {
            var src = """
interface I1
{
    public int this[int x] {get; set;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program.F = new C1 { F1 = Program.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program
{
    public static C1 F;

    static void Main()
    {
        F = new C1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f[0] += 1;
    }

    static void Test2<T>(ref T f) where T : class, I1
    {
        f[0] += 1;
    }

    static void Test3(ref C1 f)
    {
        f[0] += 1;
    }
}
""";

            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123123124:123123124:123123124").VerifyDiagnostics();
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_CompoundAssignment_03()
        {
            var src = """
using System.Threading.Tasks;

interface I1
{
    public int this[int x] {get; set;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program<T>
{
    public static T F;
}

class Program
{
    static async Task Main()
    {
        Program<C1>.F = new C1 { F1 = 123 };
        await Test1<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test2<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test3();
        System.Console.Write(Program<C1>.F.F1);
    }

    static async Task Test1<T>() where T : I1
    {
        Program<T>.F[await Get0()] += 1;
    }

    static async Task Test2<T>() where T : class, I1
    {
        Program<T>.F[await Get0()] += 1;
    }

    static async Task Test3()
    {
        Program<C1>.F[await Get0()] += 1;
    }

    static async Task<int> Get0()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 0;
    }
}
""";

            var expectedOutput = "123123125:123123125:123123125";
            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();

            comp = CreateRuntimeAsyncCompilation(src, options: TestOptions.ReleaseExe);
            var verifier = CompileAndVerify(comp, expectedOutput: RuntimeAsyncTestHelpers.ExpectedOutput(expectedOutput), verify: Verification.Fails with
            {
                ILVerifyMessage = """
                    [Main]: Return value missing on the stack. { Offset = 0x95 }
                    [Test1]: Return value missing on the stack. { Offset = 0x75 }
                    [Test2]: Return value missing on the stack. { Offset = 0x2b }
                    [Test3]: Return value missing on the stack. { Offset = 0x21 }
                    [Get0]: Unexpected type on the stack. { Offset = 0x41, Found = Int32, Expected = ref '[System.Runtime]System.Threading.Tasks.Task`1<int32>' }
                    """
            });

            verifier.VerifyIL("Program.Test1<T>()", """
                {
                  // Code size      118 (0x76)
                  .maxstack  4
                  .locals init (T V_0,
                                int V_1,
                                T V_2)
                  IL_0000:  ldloca.s   V_2
                  IL_0002:  initobj    "T"
                  IL_0008:  ldloc.2
                  IL_0009:  box        "T"
                  IL_000e:  brtrue.s   IL_0018
                  IL_0010:  ldsfld     "T Program<T>.F"
                  IL_0015:  stloc.0
                  IL_0016:  br.s       IL_001e
                  IL_0018:  ldsfld     "T Program<T>.F"
                  IL_001d:  pop
                  IL_001e:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_0023:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0028:  stloc.1
                  IL_0029:  ldloca.s   V_2
                  IL_002b:  initobj    "T"
                  IL_0031:  ldloc.2
                  IL_0032:  box        "T"
                  IL_0037:  brtrue.s   IL_003d
                  IL_0039:  ldloca.s   V_0
                  IL_003b:  br.s       IL_0042
                  IL_003d:  ldsflda    "T Program<T>.F"
                  IL_0042:  ldloc.1
                  IL_0043:  ldloca.s   V_2
                  IL_0045:  initobj    "T"
                  IL_004b:  ldloc.2
                  IL_004c:  box        "T"
                  IL_0051:  brtrue.s   IL_0057
                  IL_0053:  ldloca.s   V_0
                  IL_0055:  br.s       IL_005c
                  IL_0057:  ldsflda    "T Program<T>.F"
                  IL_005c:  ldloc.1
                  IL_005d:  constrained. "T"
                  IL_0063:  callvirt   "int I1.this[int].get"
                  IL_0068:  ldc.i4.1
                  IL_0069:  add
                  IL_006a:  constrained. "T"
                  IL_0070:  callvirt   "void I1.this[int].set"
                  IL_0075:  ret
                }
                """);
            verifier.VerifyIL("Program.Test2<T>()", """
                {
                  // Code size       44 (0x2c)
                  .maxstack  4
                  .locals init (T V_0,
                                int V_1)
                  IL_0000:  ldsfld     "T Program<T>.F"
                  IL_0005:  stloc.0
                  IL_0006:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000b:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0010:  stloc.1
                  IL_0011:  ldloc.0
                  IL_0012:  box        "T"
                  IL_0017:  ldloc.1
                  IL_0018:  ldloc.0
                  IL_0019:  box        "T"
                  IL_001e:  ldloc.1
                  IL_001f:  callvirt   "int I1.this[int].get"
                  IL_0024:  ldc.i4.1
                  IL_0025:  add
                  IL_0026:  callvirt   "void I1.this[int].set"
                  IL_002b:  ret
                }
                """);
            verifier.VerifyIL("Program.Test3()", """
                {
                  // Code size       34 (0x22)
                  .maxstack  4
                  .locals init (C1 V_0,
                                int V_1)
                  IL_0000:  ldsfld     "C1 Program<C1>.F"
                  IL_0005:  stloc.0
                  IL_0006:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000b:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0010:  stloc.1
                  IL_0011:  ldloc.0
                  IL_0012:  ldloc.1
                  IL_0013:  ldloc.0
                  IL_0014:  ldloc.1
                  IL_0015:  callvirt   "int C1.this[int].get"
                  IL_001a:  ldc.i4.1
                  IL_001b:  add
                  IL_001c:  callvirt   "void C1.this[int].set"
                  IL_0021:  ret
                }
                """);
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_CompoundAssignment_04()
        {
            var src = """
using System.Threading.Tasks;

interface I1
{
    public int this[int x] {get; set;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program<T>
{
    public static T F;
}

class Program
{
    static async Task Main()
    {
        Program<C1>.F = new C1 { F1 = 123 };
        await Test1<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test2<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test3();
        System.Console.Write(Program<C1>.F.F1);
    }

    static async Task Test1<T>() where T : I1
    {
        Program<T>.F[0] += await Get1();
    }

    static async Task Test2<T>() where T : class, I1
    {
        Program<T>.F[0] += await Get1();
    }

    static async Task Test3()
    {
        Program<C1>.F[0] += await Get1();
    }

    static async Task<int> Get1()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 1;
    }
}
""";

            var expectedOutput = "123123125:123123125:123123125";
            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();

            comp = CreateRuntimeAsyncCompilation(src, options: TestOptions.ReleaseExe);
            var verifier = CompileAndVerify(comp, expectedOutput: RuntimeAsyncTestHelpers.ExpectedOutput(expectedOutput), verify: Verification.Fails with
            {
                ILVerifyMessage = """
                    [Main]: Return value missing on the stack. { Offset = 0x95 }
                    [Test1]: Return value missing on the stack. { Offset = 0x77 }
                    [Test2]: Return value missing on the stack. { Offset = 0x36 }
                    [Test3]: Return value missing on the stack. { Offset = 0x23 }
                    [Get1]: Unexpected type on the stack. { Offset = 0x41, Found = Int32, Expected = ref '[System.Runtime]System.Threading.Tasks.Task`1<int32>' }
                    """
            });

            verifier.VerifyIL("Program.Test1<T>()", """
                {
                  // Code size      120 (0x78)
                  .maxstack  4
                  .locals init (T V_0,
                                int V_1,
                                int V_2,
                                T V_3)
                  IL_0000:  ldloca.s   V_3
                  IL_0002:  initobj    "T"
                  IL_0008:  ldloc.3
                  IL_0009:  box        "T"
                  IL_000e:  brtrue.s   IL_0018
                  IL_0010:  ldsfld     "T Program<T>.F"
                  IL_0015:  stloc.0
                  IL_0016:  br.s       IL_001e
                  IL_0018:  ldsfld     "T Program<T>.F"
                  IL_001d:  pop
                  IL_001e:  ldloca.s   V_3
                  IL_0020:  initobj    "T"
                  IL_0026:  ldloc.3
                  IL_0027:  box        "T"
                  IL_002c:  brtrue.s   IL_0032
                  IL_002e:  ldloca.s   V_0
                  IL_0030:  br.s       IL_0037
                  IL_0032:  ldsflda    "T Program<T>.F"
                  IL_0037:  ldc.i4.0
                  IL_0038:  constrained. "T"
                  IL_003e:  callvirt   "int I1.this[int].get"
                  IL_0043:  stloc.1
                  IL_0044:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_0049:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_004e:  stloc.2
                  IL_004f:  ldloca.s   V_3
                  IL_0051:  initobj    "T"
                  IL_0057:  ldloc.3
                  IL_0058:  box        "T"
                  IL_005d:  brtrue.s   IL_0063
                  IL_005f:  ldloca.s   V_0
                  IL_0061:  br.s       IL_0068
                  IL_0063:  ldsflda    "T Program<T>.F"
                  IL_0068:  ldc.i4.0
                  IL_0069:  ldloc.1
                  IL_006a:  ldloc.2
                  IL_006b:  add
                  IL_006c:  constrained. "T"
                  IL_0072:  callvirt   "void I1.this[int].set"
                  IL_0077:  ret
                }
                """);
            verifier.VerifyIL("Program.Test2<T>()", """
                {
                  // Code size       55 (0x37)
                  .maxstack  4
                  .locals init (T V_0,
                                T V_1,
                                int V_2,
                                int V_3)
                  IL_0000:  ldsfld     "T Program<T>.F"
                  IL_0005:  stloc.0
                  IL_0006:  ldloca.s   V_0
                  IL_0008:  dup
                  IL_0009:  ldobj      "T"
                  IL_000e:  stloc.1
                  IL_000f:  ldc.i4.0
                  IL_0010:  constrained. "T"
                  IL_0016:  callvirt   "int I1.this[int].get"
                  IL_001b:  stloc.2
                  IL_001c:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_0021:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0026:  stloc.3
                  IL_0027:  ldloc.1
                  IL_0028:  box        "T"
                  IL_002d:  ldc.i4.0
                  IL_002e:  ldloc.2
                  IL_002f:  ldloc.3
                  IL_0030:  add
                  IL_0031:  callvirt   "void I1.this[int].set"
                  IL_0036:  ret
                }
                """);
            verifier.VerifyIL("Program.Test3()", """
                {
                  // Code size       36 (0x24)
                  .maxstack  4
                  .locals init (C1 V_0,
                                int V_1,
                                int V_2)
                  IL_0000:  ldsfld     "C1 Program<C1>.F"
                  IL_0005:  dup
                  IL_0006:  stloc.0
                  IL_0007:  ldc.i4.0
                  IL_0008:  callvirt   "int C1.this[int].get"
                  IL_000d:  stloc.1
                  IL_000e:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_0013:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0018:  stloc.2
                  IL_0019:  ldloc.0
                  IL_001a:  ldc.i4.0
                  IL_001b:  ldloc.1
                  IL_001c:  ldloc.2
                  IL_001d:  add
                  IL_001e:  callvirt   "void C1.this[int].set"
                  IL_0023:  ret
                }
                """);
        }

        [Fact]
        public void GenericTypeParameterAsReceiver_IndexerAccess_CompoundAssignment_05()
        {
            var src = """
using System.Threading.Tasks;

interface I1
{
    public int this[int x] {get; set;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }
}

class Program<T>
{
    public static T F;
}

class Program
{
    static async Task Main()
    {
        Program<C1>.F = new C1 { F1 = 123 };
        await Test1<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test2<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test3();
        System.Console.Write(Program<C1>.F.F1);
    }

    static async Task Test1<T>() where T : I1
    {
        Program<T>.F[await Get0()] += await Get1();
    }

    static async Task Test2<T>() where T : class, I1
    {
        Program<T>.F[await Get0()] += await Get1();
    }

    static async Task Test3()
    {
        Program<C1>.F[await Get0()] += await Get1();
    }

    static async Task<int> Get0()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 1;
    }

    static async Task<int> Get1()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 1;
    }
}
""";

            var expectedOutput = "123123126:123123126:123123126";
            var comp = CreateCompilation(src, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();

            comp = CreateRuntimeAsyncCompilation(src, options: TestOptions.ReleaseExe);
            var verifier = CompileAndVerify(comp, expectedOutput: RuntimeAsyncTestHelpers.ExpectedOutput(expectedOutput), verify: Verification.Fails with
            {
                ILVerifyMessage = """
                    [Main]: Return value missing on the stack. { Offset = 0x95 }
                    [Test1]: Return value missing on the stack. { Offset = 0x89 }
                    [Test2]: Return value missing on the stack. { Offset = 0x3c }
                    [Test3]: Return value missing on the stack. { Offset = 0x32 }
                    [Get0]: Unexpected type on the stack. { Offset = 0x41, Found = Int32, Expected = ref '[System.Runtime]System.Threading.Tasks.Task`1<int32>' }
                    [Get1]: Unexpected type on the stack. { Offset = 0x41, Found = Int32, Expected = ref '[System.Runtime]System.Threading.Tasks.Task`1<int32>' }
                    """
            });

            verifier.VerifyIL("Program.Test1<T>()", """
                {
                  // Code size      138 (0x8a)
                  .maxstack  4
                  .locals init (T V_0,
                                int V_1,
                                int V_2,
                                int V_3,
                                int V_4,
                                T V_5)
                  IL_0000:  ldloca.s   V_5
                  IL_0002:  initobj    "T"
                  IL_0008:  ldloc.s    V_5
                  IL_000a:  box        "T"
                  IL_000f:  brtrue.s   IL_0019
                  IL_0011:  ldsfld     "T Program<T>.F"
                  IL_0016:  stloc.0
                  IL_0017:  br.s       IL_001f
                  IL_0019:  ldsfld     "T Program<T>.F"
                  IL_001e:  pop
                  IL_001f:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_0024:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0029:  stloc.1
                  IL_002a:  ldloc.1
                  IL_002b:  stloc.2
                  IL_002c:  ldloca.s   V_5
                  IL_002e:  initobj    "T"
                  IL_0034:  ldloc.s    V_5
                  IL_0036:  box        "T"
                  IL_003b:  brtrue.s   IL_0041
                  IL_003d:  ldloca.s   V_0
                  IL_003f:  br.s       IL_0046
                  IL_0041:  ldsflda    "T Program<T>.F"
                  IL_0046:  ldloc.1
                  IL_0047:  constrained. "T"
                  IL_004d:  callvirt   "int I1.this[int].get"
                  IL_0052:  stloc.3
                  IL_0053:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_0058:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_005d:  stloc.s    V_4
                  IL_005f:  ldloca.s   V_5
                  IL_0061:  initobj    "T"
                  IL_0067:  ldloc.s    V_5
                  IL_0069:  box        "T"
                  IL_006e:  brtrue.s   IL_0074
                  IL_0070:  ldloca.s   V_0
                  IL_0072:  br.s       IL_0079
                  IL_0074:  ldsflda    "T Program<T>.F"
                  IL_0079:  ldloc.2
                  IL_007a:  ldloc.3
                  IL_007b:  ldloc.s    V_4
                  IL_007d:  add
                  IL_007e:  constrained. "T"
                  IL_0084:  callvirt   "void I1.this[int].set"
                  IL_0089:  ret
                }
                """);
            verifier.VerifyIL("Program.Test2<T>()", """
                {
                  // Code size       61 (0x3d)
                  .maxstack  4
                  .locals init (int V_0,
                                T V_1,
                                int V_2,
                                int V_3,
                                int V_4)
                  IL_0000:  ldsfld     "T Program<T>.F"
                  IL_0005:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000a:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_000f:  stloc.0
                  IL_0010:  dup
                  IL_0011:  stloc.1
                  IL_0012:  ldloc.0
                  IL_0013:  stloc.2
                  IL_0014:  box        "T"
                  IL_0019:  ldloc.0
                  IL_001a:  callvirt   "int I1.this[int].get"
                  IL_001f:  stloc.3
                  IL_0020:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_0025:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_002a:  stloc.s    V_4
                  IL_002c:  ldloc.1
                  IL_002d:  box        "T"
                  IL_0032:  ldloc.2
                  IL_0033:  ldloc.3
                  IL_0034:  ldloc.s    V_4
                  IL_0036:  add
                  IL_0037:  callvirt   "void I1.this[int].set"
                  IL_003c:  ret
                }
                """);
            verifier.VerifyIL("Program.Test3()", """
                {
                  // Code size       51 (0x33)
                  .maxstack  4
                  .locals init (int V_0,
                                C1 V_1,
                                int V_2,
                                int V_3,
                                int V_4)
                  IL_0000:  ldsfld     "C1 Program<C1>.F"
                  IL_0005:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000a:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_000f:  stloc.0
                  IL_0010:  dup
                  IL_0011:  stloc.1
                  IL_0012:  ldloc.0
                  IL_0013:  stloc.2
                  IL_0014:  ldloc.0
                  IL_0015:  callvirt   "int C1.this[int].get"
                  IL_001a:  stloc.3
                  IL_001b:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_0020:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0025:  stloc.s    V_4
                  IL_0027:  ldloc.1
                  IL_0028:  ldloc.2
                  IL_0029:  ldloc.3
                  IL_002a:  ldloc.s    V_4
                  IL_002c:  add
                  IL_002d:  callvirt   "void C1.this[int].set"
                  IL_0032:  ret
                }
                """);
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        public void GenericTypeParameterAsReceiver_ImplicitIndexerAccess_CompoundAssignment_01()
        {
            var src = """
interface I1
{
    public int this[int x] {get; set;}
    public int Length {get;}
}

struct S1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program.F.F1++;
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }

    public int Length
    {
        get
        {
            Program.F.F1++;
            return 5;
        }
    }
}

class Program
{
    public static S1 F;

    static void Main()
    {
        F = new S1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new S1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f[^0] += 1;
    }

    static void Test2<T>(ref T f) where T : struct, I1
    {
        f[^0] += 1;
    }

    static void Test3(ref S1 f)
    {
        f[^0] += 1;
    }
}
""";

            var comp = CreateCompilation(src, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "124125125:124125125:124125125").VerifyDiagnostics();
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        public void GenericTypeParameterAsReceiver_ImplicitIndexerAccess_CompoundAssignment_02()
        {
            var src = """
interface I1
{
    public int this[int x] {get; set;}
    public int Length {get;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program.F = new C1 { F1 = Program.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }

    public int Length
    {
        get
        {
            Program.F = new C1 { F1 = Program.F.F1 + 1 };
            return 5;
        }
    }
}

class Program
{
    public static C1 F;

    static void Main()
    {
        F = new C1 { F1 = 123 };
        Test1(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test2(ref F);
        System.Console.Write(F.F1);

        System.Console.Write(":");

        F = new C1 { F1 = 123 };
        Test3(ref F);
        System.Console.Write(F.F1);
    }

    static void Test1<T>(ref T f) where T : I1
    {
        f[^0] += 1;
    }

    static void Test2<T>(ref T f) where T : class, I1
    {
        f[^0] += 1;
    }

    static void Test3(ref C1 f)
    {
        f[^0] += 1;
    }
}
""";

            var comp = CreateCompilation(src, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe);
            var verifier = CompileAndVerify(comp, expectedOutput: "123123125:123123125:123123125").VerifyDiagnostics();

            verifier.VerifyIL("Program.Test1<T>(ref T)",
@"
{
  // Code size       76 (0x4c)
  .maxstack  4
  .locals init (T& V_0,
                T V_1,
                T& V_2,
                int V_3,
                T V_4)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  stloc.2
  IL_0003:  ldloca.s   V_4
  IL_0005:  initobj    ""T""
  IL_000b:  ldloc.s    V_4
  IL_000d:  box        ""T""
  IL_0012:  brtrue.s   IL_001f
  IL_0014:  ldloc.2
  IL_0015:  ldobj      ""T""
  IL_001a:  stloc.1
  IL_001b:  ldloca.s   V_1
  IL_001d:  br.s       IL_0020
  IL_001f:  ldloc.2
  IL_0020:  stloc.0
  IL_0021:  ldloc.0
  IL_0022:  constrained. ""T""
  IL_0028:  callvirt   ""int I1.Length.get""
  IL_002d:  stloc.3
  IL_002e:  ldloc.0
  IL_002f:  ldloc.3
  IL_0030:  ldloc.0
  IL_0031:  ldloc.3
  IL_0032:  constrained. ""T""
  IL_0038:  callvirt   ""int I1.this[int].get""
  IL_003d:  ldc.i4.1
  IL_003e:  add
  IL_003f:  constrained. ""T""
  IL_0045:  callvirt   ""void I1.this[int].set""
  IL_004a:  nop
  IL_004b:  ret
}
");

            verifier.VerifyIL("Program.Test2<T>(ref T)",
@"
{
  // Code size       48 (0x30)
  .maxstack  4
  .locals init (T V_0,
                int V_1)
  IL_0000:  nop
  IL_0001:  ldarg.0
  IL_0002:  ldobj      ""T""
  IL_0007:  stloc.0
  IL_0008:  ldloc.0
  IL_0009:  box        ""T""
  IL_000e:  callvirt   ""int I1.Length.get""
  IL_0013:  stloc.1
  IL_0014:  ldloc.0
  IL_0015:  box        ""T""
  IL_001a:  ldloc.1
  IL_001b:  ldloc.0
  IL_001c:  box        ""T""
  IL_0021:  ldloc.1
  IL_0022:  callvirt   ""int I1.this[int].get""
  IL_0027:  ldc.i4.1
  IL_0028:  add
  IL_0029:  callvirt   ""void I1.this[int].set""
  IL_002e:  nop
  IL_002f:  ret
}
");
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        public void GenericTypeParameterAsReceiver_ImplicitIndexerAccess_CompoundAssignment_03()
        {
            var src = """
using System.Threading.Tasks;

interface I1
{
    public int this[int x] {get; set;}
    public int Length {get;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }

    public int Length
    {
        get
        {
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 5;
        }
    }
}

class Program<T>
{
    public static T F;
}

class Program
{
    static async Task Main()
    {
        Program<C1>.F = new C1 { F1 = 123 };
        await Test1<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test2<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test3();
        System.Console.Write(Program<C1>.F.F1);
    }

    static async Task Test1<T>() where T : I1
    {
        Program<T>.F[^await Get0()] += 1;
    }

    static async Task Test2<T>() where T : class, I1
    {
        Program<T>.F[^await Get0()] += 1;
    }

    static async Task Test3()
    {
        Program<C1>.F[^await Get0()] += 1;
    }

    static async Task<int> Get0()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 0;
    }
}
""";

            var expectedOutput = "123123126:123123126:123123126";
            var comp = CreateCompilation(src, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();

            comp = CreateRuntimeAsyncCompilation(src, options: TestOptions.ReleaseExe);
            var verifier = CompileAndVerify(comp, expectedOutput: RuntimeAsyncTestHelpers.ExpectedOutput(expectedOutput), verify: Verification.Fails with
            {
                ILVerifyMessage = """
                    [Main]: Return value missing on the stack. { Offset = 0x95 }
                    [Test1]: Return value missing on the stack. { Offset = 0x9c }
                    [Test2]: Return value missing on the stack. { Offset = 0x39 }
                    [Test3]: Return value missing on the stack. { Offset = 0x2a }
                    [Get0]: Unexpected type on the stack. { Offset = 0x41, Found = Int32, Expected = ref '[System.Runtime]System.Threading.Tasks.Task`1<int32>' }
                    """
            });

            verifier.VerifyIL("Program.Test1<T>()", """
                {
                  // Code size      157 (0x9d)
                  .maxstack  4
                  .locals init (T V_0,
                                int V_1,
                                int V_2,
                                T V_3)
                  IL_0000:  ldloca.s   V_3
                  IL_0002:  initobj    "T"
                  IL_0008:  ldloc.3
                  IL_0009:  box        "T"
                  IL_000e:  brtrue.s   IL_0018
                  IL_0010:  ldsfld     "T Program<T>.F"
                  IL_0015:  stloc.0
                  IL_0016:  br.s       IL_001e
                  IL_0018:  ldsfld     "T Program<T>.F"
                  IL_001d:  pop
                  IL_001e:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_0023:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0028:  stloc.1
                  IL_0029:  ldloca.s   V_3
                  IL_002b:  initobj    "T"
                  IL_0031:  ldloc.3
                  IL_0032:  box        "T"
                  IL_0037:  brtrue.s   IL_003d
                  IL_0039:  ldloca.s   V_0
                  IL_003b:  br.s       IL_0042
                  IL_003d:  ldsflda    "T Program<T>.F"
                  IL_0042:  constrained. "T"
                  IL_0048:  callvirt   "int I1.Length.get"
                  IL_004d:  ldloc.1
                  IL_004e:  sub
                  IL_004f:  stloc.2
                  IL_0050:  ldloca.s   V_3
                  IL_0052:  initobj    "T"
                  IL_0058:  ldloc.3
                  IL_0059:  box        "T"
                  IL_005e:  brtrue.s   IL_0064
                  IL_0060:  ldloca.s   V_0
                  IL_0062:  br.s       IL_0069
                  IL_0064:  ldsflda    "T Program<T>.F"
                  IL_0069:  ldloc.2
                  IL_006a:  ldloca.s   V_3
                  IL_006c:  initobj    "T"
                  IL_0072:  ldloc.3
                  IL_0073:  box        "T"
                  IL_0078:  brtrue.s   IL_007e
                  IL_007a:  ldloca.s   V_0
                  IL_007c:  br.s       IL_0083
                  IL_007e:  ldsflda    "T Program<T>.F"
                  IL_0083:  ldloc.2
                  IL_0084:  constrained. "T"
                  IL_008a:  callvirt   "int I1.this[int].get"
                  IL_008f:  ldc.i4.1
                  IL_0090:  add
                  IL_0091:  constrained. "T"
                  IL_0097:  callvirt   "void I1.this[int].set"
                  IL_009c:  ret
                }
                """);
            verifier.VerifyIL("Program.Test2<T>()", """
                {
                  // Code size       58 (0x3a)
                  .maxstack  4
                  .locals init (T V_0,
                                int V_1,
                                int V_2)
                  IL_0000:  ldsfld     "T Program<T>.F"
                  IL_0005:  stloc.0
                  IL_0006:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000b:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0010:  stloc.1
                  IL_0011:  ldloc.0
                  IL_0012:  box        "T"
                  IL_0017:  callvirt   "int I1.Length.get"
                  IL_001c:  ldloc.1
                  IL_001d:  sub
                  IL_001e:  stloc.2
                  IL_001f:  ldloc.0
                  IL_0020:  box        "T"
                  IL_0025:  ldloc.2
                  IL_0026:  ldloc.0
                  IL_0027:  box        "T"
                  IL_002c:  ldloc.2
                  IL_002d:  callvirt   "int I1.this[int].get"
                  IL_0032:  ldc.i4.1
                  IL_0033:  add
                  IL_0034:  callvirt   "void I1.this[int].set"
                  IL_0039:  ret
                }
                """);
            verifier.VerifyIL("Program.Test3()", """
                {
                  // Code size       43 (0x2b)
                  .maxstack  4
                  .locals init (C1 V_0,
                                int V_1,
                                int V_2)
                  IL_0000:  ldsfld     "C1 Program<C1>.F"
                  IL_0005:  stloc.0
                  IL_0006:  call       "System.Threading.Tasks.Task<int> Program.Get0()"
                  IL_000b:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0010:  stloc.1
                  IL_0011:  ldloc.0
                  IL_0012:  callvirt   "int C1.Length.get"
                  IL_0017:  ldloc.1
                  IL_0018:  sub
                  IL_0019:  stloc.2
                  IL_001a:  ldloc.0
                  IL_001b:  ldloc.2
                  IL_001c:  ldloc.0
                  IL_001d:  ldloc.2
                  IL_001e:  callvirt   "int C1.this[int].get"
                  IL_0023:  ldc.i4.1
                  IL_0024:  add
                  IL_0025:  callvirt   "void C1.this[int].set"
                  IL_002a:  ret
                }
                """);
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        public void GenericTypeParameterAsReceiver_ImplicitIndexerAccess_CompoundAssignment_04()
        {
            var src = """
using System.Threading.Tasks;

interface I1
{
    public int this[int x] {get; set;}
    public int Length {get;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }

    public int Length
    {
        get
        {
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 5;
        }
    }
}

class Program<T>
{
    public static T F;
}

class Program
{
    static async Task Main()
    {
        Program<C1>.F = new C1 { F1 = 123 };
        await Test1<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test2<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test3();
        System.Console.Write(Program<C1>.F.F1);
    }

    static async Task Test1<T>() where T : I1
    {
        Program<T>.F[^0] += await Get1();
    }

    static async Task Test2<T>() where T : class, I1
    {
        Program<T>.F[^0] += await Get1();
    }

    static async Task Test3()
    {
        Program<C1>.F[^0] += await Get1();
    }

    static async Task<int> Get1()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 1;
    }
}
""";

            var expectedOutput = "123123126:123123126:123123126";
            var comp = CreateCompilation(src, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: expectedOutput).VerifyDiagnostics();

            comp = CreateRuntimeAsyncCompilation(src, options: TestOptions.ReleaseExe);
            var verifier = CompileAndVerify(comp, expectedOutput: RuntimeAsyncTestHelpers.ExpectedOutput(expectedOutput), verify: Verification.Fails with
            {
                ILVerifyMessage = """
                    [Main]: Return value missing on the stack. { Offset = 0x95 }
                    [Test1]: Return value missing on the stack. { Offset = 0xa4 }
                    [Test2]: Return value missing on the stack. { Offset = 0x3d }
                    [Test3]: Return value missing on the stack. { Offset = 0x2e }
                    [Get1]: Unexpected type on the stack. { Offset = 0x41, Found = Int32, Expected = ref '[System.Runtime]System.Threading.Tasks.Task`1<int32>' }
                    """
            });

            verifier.VerifyIL("Program.Test1<T>()", """
                {
                  // Code size      165 (0xa5)
                  .maxstack  4
                  .locals init (T V_0,
                                int V_1,
                                int V_2,
                                int V_3,
                                int V_4,
                                T V_5)
                  IL_0000:  ldloca.s   V_5
                  IL_0002:  initobj    "T"
                  IL_0008:  ldloc.s    V_5
                  IL_000a:  box        "T"
                  IL_000f:  brtrue.s   IL_0019
                  IL_0011:  ldsfld     "T Program<T>.F"
                  IL_0016:  stloc.0
                  IL_0017:  br.s       IL_001f
                  IL_0019:  ldsfld     "T Program<T>.F"
                  IL_001e:  pop
                  IL_001f:  ldloca.s   V_5
                  IL_0021:  initobj    "T"
                  IL_0027:  ldloc.s    V_5
                  IL_0029:  box        "T"
                  IL_002e:  brtrue.s   IL_0034
                  IL_0030:  ldloca.s   V_0
                  IL_0032:  br.s       IL_0039
                  IL_0034:  ldsflda    "T Program<T>.F"
                  IL_0039:  constrained. "T"
                  IL_003f:  callvirt   "int I1.Length.get"
                  IL_0044:  stloc.1
                  IL_0045:  ldloc.1
                  IL_0046:  stloc.2
                  IL_0047:  ldloca.s   V_5
                  IL_0049:  initobj    "T"
                  IL_004f:  ldloc.s    V_5
                  IL_0051:  box        "T"
                  IL_0056:  brtrue.s   IL_005c
                  IL_0058:  ldloca.s   V_0
                  IL_005a:  br.s       IL_0061
                  IL_005c:  ldsflda    "T Program<T>.F"
                  IL_0061:  ldloc.1
                  IL_0062:  constrained. "T"
                  IL_0068:  callvirt   "int I1.this[int].get"
                  IL_006d:  stloc.3
                  IL_006e:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_0073:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0078:  stloc.s    V_4
                  IL_007a:  ldloca.s   V_5
                  IL_007c:  initobj    "T"
                  IL_0082:  ldloc.s    V_5
                  IL_0084:  box        "T"
                  IL_0089:  brtrue.s   IL_008f
                  IL_008b:  ldloca.s   V_0
                  IL_008d:  br.s       IL_0094
                  IL_008f:  ldsflda    "T Program<T>.F"
                  IL_0094:  ldloc.2
                  IL_0095:  ldloc.3
                  IL_0096:  ldloc.s    V_4
                  IL_0098:  add
                  IL_0099:  constrained. "T"
                  IL_009f:  callvirt   "void I1.this[int].set"
                  IL_00a4:  ret
                }
                """);
            verifier.VerifyIL("Program.Test2<T>()", """
                {
                  // Code size       62 (0x3e)
                  .maxstack  4
                  .locals init (int V_0,
                                T V_1,
                                int V_2,
                                int V_3,
                                int V_4)
                  IL_0000:  ldsfld     "T Program<T>.F"
                  IL_0005:  dup
                  IL_0006:  box        "T"
                  IL_000b:  callvirt   "int I1.Length.get"
                  IL_0010:  stloc.0
                  IL_0011:  dup
                  IL_0012:  stloc.1
                  IL_0013:  ldloc.0
                  IL_0014:  stloc.2
                  IL_0015:  box        "T"
                  IL_001a:  ldloc.0
                  IL_001b:  callvirt   "int I1.this[int].get"
                  IL_0020:  stloc.3
                  IL_0021:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_0026:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_002b:  stloc.s    V_4
                  IL_002d:  ldloc.1
                  IL_002e:  box        "T"
                  IL_0033:  ldloc.2
                  IL_0034:  ldloc.3
                  IL_0035:  ldloc.s    V_4
                  IL_0037:  add
                  IL_0038:  callvirt   "void I1.this[int].set"
                  IL_003d:  ret
                }
                """);
            verifier.VerifyIL("Program.Test3()", """
                {
                  // Code size       47 (0x2f)
                  .maxstack  4
                  .locals init (int V_0,
                                C1 V_1,
                                int V_2,
                                int V_3,
                                int V_4)
                  IL_0000:  ldsfld     "C1 Program<C1>.F"
                  IL_0005:  dup
                  IL_0006:  callvirt   "int C1.Length.get"
                  IL_000b:  stloc.0
                  IL_000c:  dup
                  IL_000d:  stloc.1
                  IL_000e:  ldloc.0
                  IL_000f:  stloc.2
                  IL_0010:  ldloc.0
                  IL_0011:  callvirt   "int C1.this[int].get"
                  IL_0016:  stloc.3
                  IL_0017:  call       "System.Threading.Tasks.Task<int> Program.Get1()"
                  IL_001c:  call       "int System.Runtime.CompilerServices.AsyncHelpers.Await<int>(System.Threading.Tasks.Task<int>)"
                  IL_0021:  stloc.s    V_4
                  IL_0023:  ldloc.1
                  IL_0024:  ldloc.2
                  IL_0025:  ldloc.3
                  IL_0026:  ldloc.s    V_4
                  IL_0028:  add
                  IL_0029:  callvirt   "void C1.this[int].set"
                  IL_002e:  ret
                }
                """);
        }

        [ConditionalFact(typeof(CoreClrOnly))]
        public void GenericTypeParameterAsReceiver_ImplicitIndexerAccess_CompoundAssignment_05()
        {
            var src = """
using System.Threading.Tasks;

interface I1
{
    public int this[int x] {get; set;}
    public int Length {get;}
}

class C1 : I1
{
    public int F1;

    public int this[int x]
    {
        get
        {
            System.Console.Write(F1);
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 0;
        }
        set
        {
            System.Console.Write(F1);
        }
    }

    public int Length
    {
        get
        {
            Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
            return 5;
        }
    }
}

class Program<T>
{
    public static T F;
}

class Program
{
    static async Task Main()
    {
        Program<C1>.F = new C1 { F1 = 123 };
        await Test1<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test2<C1>();
        System.Console.Write(Program<C1>.F.F1);

        System.Console.Write(":");

        Program<C1>.F = new C1 { F1 = 123 };
        await Test3();
        System.Console.Write(Program<C1>.F.F1);
    }

    static async Task Test1<T>() where T : I1
    {
        Program<T>.F[^await Get0()] += await Get1();
    }

    static async Task Test2<T>() where T : class, I1
    {
        Program<T>.F[^await Get0()] += await Get1();
    }

    static async Task Test3()
    {
        Program<C1>.F[^await Get0()] += await Get1();
    }

    static async Task<int> Get0()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 1;
    }

    static async Task<int> Get1()
    {
        Program<C1>.F = new C1 { F1 = Program<C1>.F.F1 + 1 };
        await Task.Yield();
        return 1;
    }
}
""";

            var comp = CreateCompilation(src, targetFramework: TargetFramework.NetLatest, options: TestOptions.DebugExe);
            CompileAndVerify(comp, expectedOutput: "123123127:123123127:123123127").VerifyDiagnostics();
        }
    }
}