clang-tools  14.0.0git
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 
13 using namespace clang::ast_matchers;
14 
15 namespace clang {
16 namespace tidy {
17 namespace bugprone {
18 
19 UnhandledSelfAssignmentCheck::UnhandledSelfAssignmentCheck(
20  StringRef Name, ClangTidyContext *Context)
21  : ClangTidyCheck(Name, Context),
22  WarnOnlyIfThisHasSuspiciousField(
23  Options.get("WarnOnlyIfThisHasSuspiciousField", true)) {}
24 
27  Options.store(Opts, "WarnOnlyIfThisHasSuspiciousField",
28  WarnOnlyIfThisHasSuspiciousField);
29 }
30 
32  // We don't care about deleted, default or implicit operator implementations.
33  const auto IsUserDefined = cxxMethodDecl(
34  isDefinition(), unless(anyOf(isDeleted(), isImplicit(), isDefaulted())));
35 
36  // We don't need to worry when a copy assignment operator gets the other
37  // object by value.
38  const auto HasReferenceParam =
39  cxxMethodDecl(hasParameter(0, parmVarDecl(hasType(referenceType()))));
40 
41  // Self-check: Code compares something with 'this' pointer. We don't check
42  // whether it is actually the parameter what we compare.
43  const auto HasNoSelfCheck = cxxMethodDecl(unless(hasDescendant(
44  binaryOperation(hasAnyOperatorName("==", "!="),
45  hasEitherOperand(ignoringParenCasts(cxxThisExpr()))))));
46 
47  // Both copy-and-swap and copy-and-move method creates a copy first and
48  // assign it to 'this' with swap or move.
49  // In the non-template case, we can search for the copy constructor call.
50  const auto HasNonTemplateSelfCopy = cxxMethodDecl(
51  ofClass(cxxRecordDecl(unless(hasAncestor(classTemplateDecl())))),
52  traverse(TK_AsIs,
53  hasDescendant(cxxConstructExpr(hasDeclaration(cxxConstructorDecl(
54  isCopyConstructor(), ofClass(equalsBoundNode("class"))))))));
55 
56  // In the template case, we need to handle two separate cases: 1) a local
57  // variable is created with the copy, 2) copy is created only as a temporary
58  // object.
59  const auto HasTemplateSelfCopy = cxxMethodDecl(
60  ofClass(cxxRecordDecl(hasAncestor(classTemplateDecl()))),
61  anyOf(hasDescendant(
62  varDecl(hasType(cxxRecordDecl(equalsBoundNode("class"))),
63  hasDescendant(parenListExpr()))),
64  hasDescendant(cxxUnresolvedConstructExpr(hasDescendant(declRefExpr(
65  hasType(cxxRecordDecl(equalsBoundNode("class")))))))));
66 
67  // If inside the copy assignment operator another assignment operator is
68  // called on 'this' we assume that self-check might be handled inside
69  // this nested operator.
70  const auto HasNoNestedSelfAssign =
71  cxxMethodDecl(unless(hasDescendant(cxxMemberCallExpr(callee(cxxMethodDecl(
72  hasName("operator="), ofClass(equalsBoundNode("class"))))))));
73 
74  DeclarationMatcher AdditionalMatcher = cxxMethodDecl();
75  if (WarnOnlyIfThisHasSuspiciousField) {
76  // Matcher for standard smart pointers.
77  const auto SmartPointerType = qualType(hasUnqualifiedDesugaredType(
78  recordType(hasDeclaration(classTemplateSpecializationDecl(
79  hasAnyName("::std::shared_ptr", "::std::unique_ptr",
80  "::std::weak_ptr", "::std::auto_ptr"),
81  templateArgumentCountIs(1))))));
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(cxxRecordDecl(
88  has(fieldDecl(anyOf(hasType(pointerType()), hasType(SmartPointerType),
89  hasType(arrayType())))))));
90  }
91 
92  Finder->addMatcher(cxxMethodDecl(ofClass(cxxRecordDecl().bind("class")),
93  isCopyAssignmentOperator(), IsUserDefined,
94  HasReferenceParam, HasNoSelfCheck,
95  unless(HasNonTemplateSelfCopy),
96  unless(HasTemplateSelfCopy),
97  HasNoNestedSelfAssign, AdditionalMatcher)
98  .bind("copyAssignmentOperator"),
99  this);
100 }
101 
103  const MatchFinder::MatchResult &Result) {
104  const auto *MatchedDecl =
105  Result.Nodes.getNodeAs<CXXMethodDecl>("copyAssignmentOperator");
106  diag(MatchedDecl->getLocation(),
107  "operator=() does not handle self-assignment properly");
108 }
109 
110 } // namespace bugprone
111 } // namespace tidy
112 } // namespace clang
clang::tidy::ClangTidyOptions::OptionMap
llvm::StringMap< ClangTidyValue > OptionMap
Definition: ClangTidyOptions.h:115
clang::tidy::bugprone::UnhandledSelfAssignmentCheck::storeOptions
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
Definition: UnhandledSelfAssignmentCheck.cpp:25
UnhandledSelfAssignmentCheck.h
clang::tidy::ClangTidyCheck
Base class for all clang-tidy checks.
Definition: ClangTidyCheck.h:54
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::tidy::bugprone::UnhandledSelfAssignmentCheck::registerMatchers
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Definition: UnhandledSelfAssignmentCheck.cpp:31
clang::tidy::ClangTidyCheck::Options
OptionsView Options
Definition: ClangTidyCheck.h:416
clang::tidy::ClangTidyContext
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
Definition: ClangTidyDiagnosticConsumer.h:71
Name
static constexpr llvm::StringLiteral Name
Definition: UppercaseLiteralSuffixCheck.cpp:28
clang::tidy::ClangTidyCheck::diag
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
Definition: ClangTidyCheck.cpp:25
clang::tidy::bugprone::UnhandledSelfAssignmentCheck::check
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Definition: UnhandledSelfAssignmentCheck.cpp:102
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::tidy::ClangTidyCheck::OptionsView::store
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.
Definition: ClangTidyCheck.cpp:120