clang-tools  9.0.0
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  if (!getLangOpts().CPlusPlus)
33  return;
34 
35  // We don't care about deleted, default or implicit operator implementations.
36  const auto IsUserDefined = cxxMethodDecl(
37  isDefinition(), unless(anyOf(isDeleted(), isImplicit(), isDefaulted())));
38 
39  // We don't need to worry when a copy assignment operator gets the other
40  // object by value.
41  const auto HasReferenceParam =
42  cxxMethodDecl(hasParameter(0, parmVarDecl(hasType(referenceType()))));
43 
44  // Self-check: Code compares something with 'this' pointer. We don't check
45  // whether it is actually the parameter what we compare.
46  const auto HasNoSelfCheck = cxxMethodDecl(unless(hasDescendant(
47  binaryOperator(anyOf(hasOperatorName("=="), hasOperatorName("!=")),
48  has(ignoringParenCasts(cxxThisExpr()))))));
49 
50  // Both copy-and-swap and copy-and-move method creates a copy first and
51  // assign it to 'this' with swap or move.
52  // In the non-template case, we can search for the copy constructor call.
53  const auto HasNonTemplateSelfCopy = cxxMethodDecl(
54  ofClass(cxxRecordDecl(unless(hasAncestor(classTemplateDecl())))),
55  hasDescendant(cxxConstructExpr(hasDeclaration(cxxConstructorDecl(
56  isCopyConstructor(), ofClass(equalsBoundNode("class")))))));
57 
58  // In the template case, we need to handle two separate cases: 1) a local
59  // variable is created with the copy, 2) copy is created only as a temporary
60  // object.
61  const auto HasTemplateSelfCopy = cxxMethodDecl(
62  ofClass(cxxRecordDecl(hasAncestor(classTemplateDecl()))),
63  anyOf(hasDescendant(
64  varDecl(hasType(cxxRecordDecl(equalsBoundNode("class"))),
65  hasDescendant(parenListExpr()))),
66  hasDescendant(cxxUnresolvedConstructExpr(hasDescendant(declRefExpr(
67  hasType(cxxRecordDecl(equalsBoundNode("class")))))))));
68 
69  // If inside the copy assignment operator another assignment operator is
70  // called on 'this' we assume that self-check might be handled inside
71  // this nested operator.
72  const auto HasNoNestedSelfAssign =
73  cxxMethodDecl(unless(hasDescendant(cxxMemberCallExpr(callee(cxxMethodDecl(
74  hasName("operator="), ofClass(equalsBoundNode("class"))))))));
75 
76  DeclarationMatcher AdditionalMatcher = cxxMethodDecl();
77  if (WarnOnlyIfThisHasSuspiciousField) {
78  // Matcher for standard smart pointers.
79  const auto SmartPointerType = qualType(hasUnqualifiedDesugaredType(
80  recordType(hasDeclaration(classTemplateSpecializationDecl(
81  hasAnyName("::std::shared_ptr", "::std::unique_ptr",
82  "::std::weak_ptr", "::std::auto_ptr"),
83  templateArgumentCountIs(1))))));
84 
85  // We will warn only if the class has a pointer or a C array field which
86  // probably causes a problem during self-assignment (e.g. first resetting
87  // the pointer member, then trying to access the object pointed by the
88  // pointer, or memcpy overlapping arrays).
89  AdditionalMatcher = cxxMethodDecl(ofClass(cxxRecordDecl(
90  has(fieldDecl(anyOf(hasType(pointerType()), hasType(SmartPointerType),
91  hasType(arrayType())))))));
92  }
93 
94  Finder->addMatcher(cxxMethodDecl(ofClass(cxxRecordDecl().bind("class")),
95  isCopyAssignmentOperator(), IsUserDefined,
96  HasReferenceParam, HasNoSelfCheck,
97  unless(HasNonTemplateSelfCopy),
98  unless(HasTemplateSelfCopy),
99  HasNoNestedSelfAssign, AdditionalMatcher)
100  .bind("copyAssignmentOperator"),
101  this);
102 }
103 
105  const MatchFinder::MatchResult &Result) {
106  const auto *MatchedDecl =
107  Result.Nodes.getNodeAs<CXXMethodDecl>("copyAssignmentOperator");
108  diag(MatchedDecl->getLocation(),
109  "operator=() does not handle self-assignment properly");
110 }
111 
112 } // namespace bugprone
113 } // namespace tidy
114 } // namespace clang
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Base class for all clang-tidy checks.
const LangOptions & getLangOpts() const
Returns the language options from the context.
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.
static constexpr llvm::StringLiteral Name
std::map< std::string, std::string > OptionMap
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
llvm::Optional< llvm::Expected< tooling::AtomicChanges > > Result
Definition: Rename.cpp:36
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check&#39;s name.