1//===--- ComparePointerToMemberVirtualFunctionCheck.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 "ComparePointerToMemberVirtualFunctionCheck.h"
10#include "clang/AST/ASTContext.h"
11#include "clang/AST/ASTTypeTraits.h"
12#include "clang/AST/DeclCXX.h"
13#include "clang/AST/OperationKinds.h"
14#include "clang/AST/Type.h"
15#include "clang/ASTMatchers/ASTMatchFinder.h"
16#include "clang/ASTMatchers/ASTMatchers.h"
17#include "clang/ASTMatchers/ASTMatchersMacros.h"
18#include "clang/Basic/Diagnostic.h"
19#include "clang/Basic/DiagnosticIDs.h"
20#include "llvm/ADT/SmallVector.h"
21
22using namespace clang::ast_matchers;
23
24namespace clang::tidy::bugprone {
25
26namespace {
27
28AST_MATCHER(CXXMethodDecl, isVirtual) { return Node.isVirtual(); }
29
30static const char *const ErrorMsg =
31 "comparing a pointer to member virtual function with other pointer is "
32 "unspecified behavior, only compare it with a null-pointer constant for "
33 "equality.";
34
35} // namespace
36
37void ComparePointerToMemberVirtualFunctionCheck::registerMatchers(
38 MatchFinder *Finder) {
39
40 auto DirectMemberVirtualFunctionPointer = unaryOperator(
41 allOf(hasOperatorName(Name: "&"),
42 hasUnaryOperand(InnerMatcher: declRefExpr(to(InnerMatcher: cxxMethodDecl(isVirtual()))))));
43 auto IndirectMemberPointer =
44 ignoringImpCasts(InnerMatcher: declRefExpr().bind(ID: "indirect_member_pointer"));
45
46 Finder->addMatcher(
47 NodeMatch: binaryOperator(
48 allOf(hasAnyOperatorName("==", "!="),
49 hasEitherOperand(
50 InnerMatcher: hasType(InnerMatcher: memberPointerType(pointee(functionType())))),
51 anyOf(hasEitherOperand(InnerMatcher: DirectMemberVirtualFunctionPointer),
52 hasEitherOperand(InnerMatcher: IndirectMemberPointer)),
53 unless(hasEitherOperand(
54 InnerMatcher: castExpr(hasCastKind(Kind: CK_NullToMemberPointer))))))
55 .bind(ID: "binary_operator"),
56 Action: this);
57}
58
59void ComparePointerToMemberVirtualFunctionCheck::check(
60 const MatchFinder::MatchResult &Result) {
61 const auto *BO = Result.Nodes.getNodeAs<BinaryOperator>(ID: "binary_operator");
62 const auto *DRE =
63 Result.Nodes.getNodeAs<DeclRefExpr>(ID: "indirect_member_pointer");
64
65 if (DRE == nullptr) {
66 // compare with pointer to member virtual function.
67 diag(Loc: BO->getOperatorLoc(), Description: ErrorMsg);
68 return;
69 }
70 // compare with variable which type is pointer to member function.
71 llvm::SmallVector<SourceLocation, 12U> SameSignatureVirtualMethods{};
72 const auto *MPT = cast<MemberPointerType>(DRE->getType().getCanonicalType());
73 const Type *T = MPT->getClass();
74 if (T == nullptr)
75 return;
76 const CXXRecordDecl *RD = T->getAsCXXRecordDecl();
77 if (RD == nullptr)
78 return;
79
80 constexpr bool StopVisit = false;
81
82 auto VisitSameSignatureVirtualMethods =
83 [&](const CXXRecordDecl *CurrentRecordDecl) -> bool {
84 bool Ret = !StopVisit;
85 for (const auto *MD : CurrentRecordDecl->methods()) {
86 if (MD->isVirtual() && MD->getType() == MPT->getPointeeType()) {
87 SameSignatureVirtualMethods.push_back(Elt: MD->getBeginLoc());
88 Ret = StopVisit;
89 }
90 }
91 return Ret;
92 };
93
94 if (StopVisit != VisitSameSignatureVirtualMethods(RD)) {
95 RD->forallBases(BaseMatches: VisitSameSignatureVirtualMethods);
96 }
97
98 if (!SameSignatureVirtualMethods.empty()) {
99 diag(Loc: BO->getOperatorLoc(), Description: ErrorMsg);
100 for (const auto Loc : SameSignatureVirtualMethods)
101 diag(Loc, Description: "potential member virtual function is declared here.",
102 Level: DiagnosticIDs::Note);
103 }
104}
105
106} // namespace clang::tidy::bugprone
107

source code of clang-tools-extra/clang-tidy/bugprone/ComparePointerToMemberVirtualFunctionCheck.cpp