1 //===--- MutatingCopyCheck.cpp - clang-tidy -------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "MutatingCopyCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 
13 using namespace clang::ast_matchers;
14 
15 namespace clang {
16 namespace tidy {
17 namespace cert {
18 
19 static constexpr llvm::StringLiteral SourceDeclName = "ChangedPVD";
20 static constexpr llvm::StringLiteral MutatingOperatorName = "MutatingOp";
21 static constexpr llvm::StringLiteral MutatingCallName = "MutatingCall";
22 
23 void MutatingCopyCheck::registerMatchers(MatchFinder *Finder) {
24   const auto MemberExprOrSourceObject = anyOf(
25       memberExpr(),
26       declRefExpr(to(decl(equalsBoundNode(std::string(SourceDeclName))))));
27 
28   const auto IsPartOfSource =
29       allOf(unless(hasDescendant(expr(unless(MemberExprOrSourceObject)))),
30             MemberExprOrSourceObject);
31 
32   const auto IsSourceMutatingAssignment = traverse(
33       TK_AsIs, binaryOperation(hasOperatorName("="), hasLHS(IsPartOfSource))
34                    .bind(MutatingOperatorName));
35 
36   const auto MemberExprOrSelf = anyOf(memberExpr(), cxxThisExpr());
37 
38   const auto IsPartOfSelf = allOf(
39       unless(hasDescendant(expr(unless(MemberExprOrSelf)))), MemberExprOrSelf);
40 
41   const auto IsSelfMutatingAssignment =
42       binaryOperation(isAssignmentOperator(), hasLHS(IsPartOfSelf));
43 
44   const auto IsSelfMutatingMemberFunction =
45       functionDecl(hasBody(hasDescendant(IsSelfMutatingAssignment)));
46 
47   const auto IsSourceMutatingMemberCall =
48       cxxMemberCallExpr(on(IsPartOfSource),
49                         callee(IsSelfMutatingMemberFunction))
50           .bind(MutatingCallName);
51 
52   const auto MutatesSource = allOf(
53       hasParameter(
54           0, parmVarDecl(hasType(lValueReferenceType())).bind(SourceDeclName)),
55       anyOf(forEachDescendant(IsSourceMutatingAssignment),
56             forEachDescendant(IsSourceMutatingMemberCall)));
57 
58   Finder->addMatcher(cxxConstructorDecl(isCopyConstructor(), MutatesSource),
59                      this);
60 
61   Finder->addMatcher(cxxMethodDecl(isCopyAssignmentOperator(), MutatesSource),
62                      this);
63 }
64 
65 void MutatingCopyCheck::check(const MatchFinder::MatchResult &Result) {
66   if (const auto *MemberCall =
67           Result.Nodes.getNodeAs<CXXMemberCallExpr>(MutatingCallName))
68     diag(MemberCall->getBeginLoc(), "call mutates copied object");
69   else if (const auto *Assignment =
70                Result.Nodes.getNodeAs<Expr>(MutatingOperatorName))
71     diag(Assignment->getBeginLoc(), "mutating copied object");
72 }
73 
74 } // namespace cert
75 } // namespace tidy
76 } // namespace clang
77