1//===--- UnhandledSelfAssignmentCheck.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 "UnhandledSelfAssignmentCheck.h"
10#include "clang/AST/ASTContext.h"
11#include "clang/ASTMatchers/ASTMatchFinder.h"
12
13using namespace clang::ast_matchers;
14
15namespace clang::tidy::bugprone {
16
17UnhandledSelfAssignmentCheck::UnhandledSelfAssignmentCheck(
18 StringRef Name, ClangTidyContext *Context)
19 : ClangTidyCheck(Name, Context),
20 WarnOnlyIfThisHasSuspiciousField(
21 Options.get(LocalName: "WarnOnlyIfThisHasSuspiciousField", Default: true)) {}
22
23void UnhandledSelfAssignmentCheck::storeOptions(
24 ClangTidyOptions::OptionMap &Opts) {
25 Options.store(Options&: Opts, LocalName: "WarnOnlyIfThisHasSuspiciousField",
26 Value: WarnOnlyIfThisHasSuspiciousField);
27}
28
29void UnhandledSelfAssignmentCheck::registerMatchers(MatchFinder *Finder) {
30 // We don't care about deleted, default or implicit operator implementations.
31 const auto IsUserDefined = cxxMethodDecl(
32 isDefinition(), unless(anyOf(isDeleted(), isImplicit(), isDefaulted())));
33
34 // We don't need to worry when a copy assignment operator gets the other
35 // object by value.
36 const auto HasReferenceParam =
37 cxxMethodDecl(hasParameter(N: 0, InnerMatcher: parmVarDecl(hasType(InnerMatcher: referenceType()))));
38
39 // Self-check: Code compares something with 'this' pointer. We don't check
40 // whether it is actually the parameter what we compare.
41 const auto HasNoSelfCheck = cxxMethodDecl(unless(hasDescendant(
42 binaryOperation(hasAnyOperatorName("==", "!="),
43 hasEitherOperand(InnerMatcher: ignoringParenCasts(InnerMatcher: cxxThisExpr()))))));
44
45 // Both copy-and-swap and copy-and-move method creates a copy first and
46 // assign it to 'this' with swap or move.
47 // In the non-template case, we can search for the copy constructor call.
48 const auto HasNonTemplateSelfCopy = cxxMethodDecl(
49 ofClass(InnerMatcher: cxxRecordDecl(unless(hasAncestor(classTemplateDecl())))),
50 traverse(TK: TK_AsIs,
51 InnerMatcher: hasDescendant(cxxConstructExpr(hasDeclaration(InnerMatcher: cxxConstructorDecl(
52 isCopyConstructor(), ofClass(InnerMatcher: equalsBoundNode(ID: "class"))))))));
53
54 // In the template case, we need to handle two separate cases: 1) a local
55 // variable is created with the copy, 2) copy is created only as a temporary
56 // object.
57 const auto HasTemplateSelfCopy = cxxMethodDecl(
58 ofClass(InnerMatcher: cxxRecordDecl(hasAncestor(classTemplateDecl()))),
59 anyOf(hasDescendant(
60 varDecl(hasType(InnerMatcher: cxxRecordDecl(equalsBoundNode(ID: "class"))),
61 hasDescendant(parenListExpr()))),
62 hasDescendant(cxxUnresolvedConstructExpr(hasDescendant(declRefExpr(
63 hasType(InnerMatcher: cxxRecordDecl(equalsBoundNode(ID: "class")))))))));
64
65 // If inside the copy assignment operator another assignment operator is
66 // called on 'this' we assume that self-check might be handled inside
67 // this nested operator.
68 const auto HasNoNestedSelfAssign =
69 cxxMethodDecl(unless(hasDescendant(cxxMemberCallExpr(callee(InnerMatcher: cxxMethodDecl(
70 hasName(Name: "operator="), ofClass(InnerMatcher: equalsBoundNode(ID: "class"))))))));
71
72 DeclarationMatcher AdditionalMatcher = cxxMethodDecl();
73 if (WarnOnlyIfThisHasSuspiciousField) {
74 // Matcher for standard smart pointers.
75 const auto SmartPointerType = qualType(hasUnqualifiedDesugaredType(
76 InnerMatcher: recordType(hasDeclaration(InnerMatcher: classTemplateSpecializationDecl(
77 anyOf(allOf(hasAnyName("::std::shared_ptr", "::std::weak_ptr",
78 "::std::auto_ptr"),
79 templateArgumentCountIs(N: 1)),
80 allOf(hasName(Name: "::std::unique_ptr"),
81 templateArgumentCountIs(N: 2))))))));
82
83 // We will warn only if the class has a pointer or a C array field which
84 // probably causes a problem during self-assignment (e.g. first resetting
85 // the pointer member, then trying to access the object pointed by the
86 // pointer, or memcpy overlapping arrays).
87 AdditionalMatcher = cxxMethodDecl(ofClass(InnerMatcher: cxxRecordDecl(
88 has(fieldDecl(anyOf(hasType(InnerMatcher: pointerType()), hasType(InnerMatcher: SmartPointerType),
89 hasType(InnerMatcher: arrayType())))))));
90 }
91
92 Finder->addMatcher(NodeMatch: cxxMethodDecl(ofClass(InnerMatcher: cxxRecordDecl().bind(ID: "class")),
93 isCopyAssignmentOperator(), IsUserDefined,
94 HasReferenceParam, HasNoSelfCheck,
95 unless(HasNonTemplateSelfCopy),
96 unless(HasTemplateSelfCopy),
97 HasNoNestedSelfAssign, AdditionalMatcher)
98 .bind(ID: "copyAssignmentOperator"),
99 Action: this);
100}
101
102void UnhandledSelfAssignmentCheck::check(
103 const MatchFinder::MatchResult &Result) {
104 const auto *MatchedDecl =
105 Result.Nodes.getNodeAs<CXXMethodDecl>(ID: "copyAssignmentOperator");
106 diag(MatchedDecl->getLocation(),
107 "operator=() does not handle self-assignment properly");
108}
109
110} // namespace clang::tidy::bugprone
111

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