clang-tools 20.0.0git
UnhandledSelfAssignmentCheck.cpp
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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
10#include "clang/AST/ASTContext.h"
11#include "clang/ASTMatchers/ASTMatchFinder.h"
12
13using namespace clang::ast_matchers;
14
15namespace clang::tidy::bugprone {
16
18 StringRef Name, ClangTidyContext *Context)
19 : ClangTidyCheck(Name, Context),
20 WarnOnlyIfThisHasSuspiciousField(
21 Options.get("WarnOnlyIfThisHasSuspiciousField", true)) {}
22
25 Options.store(Opts, "WarnOnlyIfThisHasSuspiciousField",
26 WarnOnlyIfThisHasSuspiciousField);
27}
28
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(0, parmVarDecl(hasType(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(ignoringParenCasts(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(cxxRecordDecl(unless(hasAncestor(classTemplateDecl())))),
50 traverse(TK_AsIs,
51 hasDescendant(cxxConstructExpr(hasDeclaration(cxxConstructorDecl(
52 isCopyConstructor(), ofClass(equalsBoundNode("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(cxxRecordDecl(hasAncestor(classTemplateDecl()))),
59 anyOf(hasDescendant(
60 varDecl(hasType(cxxRecordDecl(equalsBoundNode("class"))),
61 hasDescendant(parenListExpr()))),
62 hasDescendant(cxxUnresolvedConstructExpr(hasDescendant(declRefExpr(
63 hasType(cxxRecordDecl(equalsBoundNode("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(cxxMethodDecl(
70 hasName("operator="), ofClass(equalsBoundNode("class"))))))));
71
72 DeclarationMatcher AdditionalMatcher = cxxMethodDecl();
73 if (WarnOnlyIfThisHasSuspiciousField) {
74 // Matcher for standard smart pointers.
75 const auto SmartPointerType = qualType(hasUnqualifiedDesugaredType(
76 recordType(hasDeclaration(classTemplateSpecializationDecl(
77 hasAnyName("::std::shared_ptr", "::std::unique_ptr",
78 "::std::weak_ptr", "::std::auto_ptr"),
79 templateArgumentCountIs(1))))));
80
81 // We will warn only if the class has a pointer or a C array field which
82 // probably causes a problem during self-assignment (e.g. first resetting
83 // the pointer member, then trying to access the object pointed by the
84 // pointer, or memcpy overlapping arrays).
85 AdditionalMatcher = cxxMethodDecl(ofClass(cxxRecordDecl(
86 has(fieldDecl(anyOf(hasType(pointerType()), hasType(SmartPointerType),
87 hasType(arrayType())))))));
88 }
89
90 Finder->addMatcher(cxxMethodDecl(ofClass(cxxRecordDecl().bind("class")),
91 isCopyAssignmentOperator(), IsUserDefined,
92 HasReferenceParam, HasNoSelfCheck,
93 unless(HasNonTemplateSelfCopy),
94 unless(HasTemplateSelfCopy),
95 HasNoNestedSelfAssign, AdditionalMatcher)
96 .bind("copyAssignmentOperator"),
97 this);
98}
99
101 const MatchFinder::MatchResult &Result) {
102 const auto *MatchedDecl =
103 Result.Nodes.getNodeAs<CXXMethodDecl>("copyAssignmentOperator");
104 diag(MatchedDecl->getLocation(),
105 "operator=() does not handle self-assignment properly");
106}
107
108} // namespace clang::tidy::bugprone
llvm::SmallString< 256U > Name
void store(ClangTidyOptions::OptionMap &Options, StringRef LocalName, StringRef Value) const
Stores an option with the check-local name LocalName with string value Value to Options.
Base class for all clang-tidy checks.
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
UnhandledSelfAssignmentCheck(StringRef Name, ClangTidyContext *Context)
llvm::StringMap< ClangTidyValue > OptionMap