llvm-project

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//===--- AssertSideEffectCheck.cpp - clang-tidy ---------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "AssertSideEffectCheck.h"
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#include "../utils/Matchers.h"
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#include "../utils/OptionsUtils.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/Frontend/CompilerInstance.h"
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#include "clang/Lex/Lexer.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/Casting.h"
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#include <algorithm>
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#include <string>
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using namespace clang::ast_matchers;
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namespace clang::tidy::bugprone {
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namespace {
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AST_MATCHER_P2(Expr, hasSideEffect, bool, CheckFunctionCalls,
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               clang::ast_matchers::internal::Matcher<NamedDecl>,
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               IgnoredFunctionsMatcher) {
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  const Expr *E = &Node;
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  if (const auto *Op = dyn_cast<UnaryOperator>(E)) {
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    UnaryOperator::Opcode OC = Op->getOpcode();
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    return OC == UO_PostInc || OC == UO_PostDec || OC == UO_PreInc ||
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           OC == UO_PreDec;
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  }
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  if (const auto *Op = dyn_cast<BinaryOperator>(E)) {
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    return Op->isAssignmentOp();
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  }
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  if (const auto *OpCallExpr = dyn_cast<CXXOperatorCallExpr>(E)) {
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    if (const auto *MethodDecl =
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            dyn_cast_or_null<CXXMethodDecl>(OpCallExpr->getDirectCallee()))
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      if (MethodDecl->isConst())
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        return false;
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    OverloadedOperatorKind OpKind = OpCallExpr->getOperator();
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    return OpKind == OO_Equal || OpKind == OO_PlusEqual ||
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           OpKind == OO_MinusEqual || OpKind == OO_StarEqual ||
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           OpKind == OO_SlashEqual || OpKind == OO_AmpEqual ||
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           OpKind == OO_PipeEqual || OpKind == OO_CaretEqual ||
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           OpKind == OO_LessLessEqual || OpKind == OO_GreaterGreaterEqual ||
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           OpKind == OO_LessLess || OpKind == OO_GreaterGreater ||
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           OpKind == OO_PlusPlus || OpKind == OO_MinusMinus ||
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           OpKind == OO_PercentEqual || OpKind == OO_New ||
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           OpKind == OO_Delete || OpKind == OO_Array_New ||
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           OpKind == OO_Array_Delete;
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  }
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  if (const auto *CExpr = dyn_cast<CallExpr>(E)) {
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    if (!CheckFunctionCalls)
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      return false;
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    if (const auto *FuncDecl = CExpr->getDirectCallee()) {
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      if (FuncDecl->getDeclName().isIdentifier() &&
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          IgnoredFunctionsMatcher.matches(*FuncDecl, Finder,
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                                          Builder)) // exceptions come here
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        return false;
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      for (size_t I = 0; I < FuncDecl->getNumParams(); I++) {
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        const ParmVarDecl *P = FuncDecl->getParamDecl(I);
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        const Expr *ArgExpr =
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            I < CExpr->getNumArgs() ? CExpr->getArg(I) : nullptr;
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        const QualType PT = P->getType().getCanonicalType();
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        if (ArgExpr && !ArgExpr->isXValue() && PT->isReferenceType() &&
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            !PT.getNonReferenceType().isConstQualified())
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          return true;
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      }
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      if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FuncDecl))
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        return !MethodDecl->isConst();
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    }
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    return true;
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  }
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  return isa<CXXNewExpr>(E) || isa<CXXDeleteExpr>(E) || isa<CXXThrowExpr>(E);
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}
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} // namespace
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AssertSideEffectCheck::AssertSideEffectCheck(StringRef Name,
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                                             ClangTidyContext *Context)
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    : ClangTidyCheck(Name, Context),
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      CheckFunctionCalls(Options.get("CheckFunctionCalls", false)),
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      RawAssertList(Options.get("AssertMacros", "assert,NSAssert,NSCAssert")),
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      IgnoredFunctions(utils::options::parseListPair(
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          "__builtin_expect;", Options.get("IgnoredFunctions", ""))) {
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  StringRef(RawAssertList).split(AssertMacros, ",", -1, false);
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}
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// The options are explained in AssertSideEffectCheck.h.
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void AssertSideEffectCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
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  Options.store(Opts, "CheckFunctionCalls", CheckFunctionCalls);
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  Options.store(Opts, "AssertMacros", RawAssertList);
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  Options.store(Opts, "IgnoredFunctions",
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                utils::options::serializeStringList(IgnoredFunctions));
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}
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void AssertSideEffectCheck::registerMatchers(MatchFinder *Finder) {
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  auto IgnoredFunctionsMatcher =
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      matchers::matchesAnyListedName(IgnoredFunctions);
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  auto DescendantWithSideEffect =
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      traverse(TK_AsIs, hasDescendant(expr(hasSideEffect(
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                            CheckFunctionCalls, IgnoredFunctionsMatcher))));
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  auto ConditionWithSideEffect = hasCondition(DescendantWithSideEffect);
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  Finder->addMatcher(
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      stmt(
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          anyOf(conditionalOperator(ConditionWithSideEffect),
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                ifStmt(ConditionWithSideEffect),
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                unaryOperator(hasOperatorName("!"),
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                              hasUnaryOperand(unaryOperator(
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                                  hasOperatorName("!"),
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                                  hasUnaryOperand(DescendantWithSideEffect))))))
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          .bind("condStmt"),
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      this);
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}
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void AssertSideEffectCheck::check(const MatchFinder::MatchResult &Result) {
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  const SourceManager &SM = *Result.SourceManager;
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  const LangOptions LangOpts = getLangOpts();
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  SourceLocation Loc = Result.Nodes.getNodeAs<Stmt>("condStmt")->getBeginLoc();
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  StringRef AssertMacroName;
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  while (Loc.isValid() && Loc.isMacroID()) {
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    StringRef MacroName = Lexer::getImmediateMacroName(Loc, SM, LangOpts);
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    Loc = SM.getImmediateMacroCallerLoc(Loc);
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    // Check if this macro is an assert.
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    if (llvm::is_contained(AssertMacros, MacroName)) {
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      AssertMacroName = MacroName;
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      break;
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    }
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  }
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  if (AssertMacroName.empty())
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    return;
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  diag(Loc, "side effect in %0() condition discarded in release builds")
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      << AssertMacroName;
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}
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} // namespace clang::tidy::bugprone
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