CopyConstructorMutatesArgumentCheck.cpp

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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "CopyConstructorMutatesArgumentCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
 
using namespace clang::ast_matchers;
 
namespace clang::tidy::bugprone {
 
static constexpr llvm::StringLiteral SourceDeclName = "ChangedPVD";
static constexpr llvm::StringLiteral MutatingOperatorName = "MutatingOp";
static constexpr llvm::StringLiteral MutatingCallName = "MutatingCall";
 
void CopyConstructorMutatesArgumentCheck::registerMatchers(
    MatchFinder *Finder) {
  const auto MemberExprOrSourceObject = anyOf(
      memberExpr(),
      declRefExpr(to(decl(equalsBoundNode(std::string(SourceDeclName))))));
 
  const auto IsPartOfSource =
      allOf(unless(hasDescendant(expr(unless(MemberExprOrSourceObject)))),
            MemberExprOrSourceObject);
 
  const auto IsSourceMutatingAssignment = traverse(
      TK_AsIs, binaryOperation(hasOperatorName("="), hasLHS(IsPartOfSource))
                   .bind(MutatingOperatorName));
 
  const auto MemberExprOrSelf = anyOf(memberExpr(), cxxThisExpr());
 
  const auto IsPartOfSelf = allOf(
      unless(hasDescendant(expr(unless(MemberExprOrSelf)))), MemberExprOrSelf);
 
  const auto IsSelfMutatingAssignment =
      binaryOperation(isAssignmentOperator(), hasLHS(IsPartOfSelf));
 
  const auto IsSelfMutatingMemberFunction =
      functionDecl(hasBody(hasDescendant(IsSelfMutatingAssignment)));
 
  const auto IsSourceMutatingMemberCall =
      cxxMemberCallExpr(on(IsPartOfSource),
                        callee(IsSelfMutatingMemberFunction))
          .bind(MutatingCallName);
 
  const auto MutatesSource = allOf(
      hasParameter(
          0, parmVarDecl(hasType(lValueReferenceType())).bind(SourceDeclName)),
      anyOf(forEachDescendant(IsSourceMutatingAssignment),
            forEachDescendant(IsSourceMutatingMemberCall)));
 
  Finder->addMatcher(cxxConstructorDecl(isCopyConstructor(), MutatesSource),
                     this);
 
  Finder->addMatcher(cxxMethodDecl(isCopyAssignmentOperator(), MutatesSource),
                     this);
}
 
void CopyConstructorMutatesArgumentCheck::check(
    const MatchFinder::MatchResult &Result) {
  if (const auto *MemberCall =
          Result.Nodes.getNodeAs<CXXMemberCallExpr>(MutatingCallName))
    diag(MemberCall->getBeginLoc(), "call mutates copied object");
  else if (const auto *Assignment =
               Result.Nodes.getNodeAs<Expr>(MutatingOperatorName))
    diag(Assignment->getBeginLoc(), "mutating copied object");
}
 
} // namespace clang::tidy::bugprone