clang-tools  4.0.0
UnconventionalAssignOperatorCheck.cpp
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1 //===--- UnconventionalAssignOperatorCheck.cpp - clang-tidy -----*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/ASTMatchers/ASTMatchers.h"
13 
14 using namespace clang::ast_matchers;
15 
16 namespace clang {
17 namespace tidy {
18 namespace misc {
19 
20 void UnconventionalAssignOperatorCheck::registerMatchers(
21  ast_matchers::MatchFinder *Finder) {
22  // Only register the matchers for C++; the functionality currently does not
23  // provide any benefit to other languages, despite being benign.
24  if (!getLangOpts().CPlusPlus)
25  return;
26 
27  const auto HasGoodReturnType = cxxMethodDecl(returns(
28  lValueReferenceType(pointee(unless(isConstQualified()),
29  hasDeclaration(equalsBoundNode("class"))))));
30 
31  const auto IsSelf = qualType(
32  anyOf(hasDeclaration(equalsBoundNode("class")),
33  referenceType(pointee(hasDeclaration(equalsBoundNode("class"))))));
34  const auto IsAssign =
35  cxxMethodDecl(unless(anyOf(isDeleted(), isPrivate(), isImplicit())),
36  hasName("operator="), ofClass(recordDecl().bind("class")))
37  .bind("method");
38  const auto IsSelfAssign =
39  cxxMethodDecl(IsAssign, hasParameter(0, parmVarDecl(hasType(IsSelf))))
40  .bind("method");
41 
42  Finder->addMatcher(
43  cxxMethodDecl(IsAssign, unless(HasGoodReturnType)).bind("ReturnType"),
44  this);
45 
46  const auto BadSelf = referenceType(
47  anyOf(lValueReferenceType(pointee(unless(isConstQualified()))),
48  rValueReferenceType(pointee(isConstQualified()))));
49 
50  Finder->addMatcher(
51  cxxMethodDecl(IsSelfAssign,
52  hasParameter(0, parmVarDecl(hasType(BadSelf))))
53  .bind("ArgumentType"),
54  this);
55 
56  Finder->addMatcher(
57  cxxMethodDecl(IsSelfAssign, anyOf(isConst(), isVirtual())).bind("cv"),
58  this);
59 
60  const auto IsBadReturnStatement = returnStmt(unless(has(ignoringParenImpCasts(
61  unaryOperator(hasOperatorName("*"), hasUnaryOperand(cxxThisExpr()))))));
62  const auto IsGoodAssign = cxxMethodDecl(IsAssign, HasGoodReturnType);
63 
64  Finder->addMatcher(returnStmt(IsBadReturnStatement, forFunction(IsGoodAssign))
65  .bind("returnStmt"),
66  this);
67 }
68 
69 void UnconventionalAssignOperatorCheck::check(
70  const MatchFinder::MatchResult &Result) {
71  if (const auto *RetStmt = Result.Nodes.getNodeAs<ReturnStmt>("returnStmt")) {
72  diag(RetStmt->getLocStart(), "operator=() should always return '*this'");
73  } else {
74  static const char *const Messages[][2] = {
75  {"ReturnType", "operator=() should return '%0&'"},
76  {"ArgumentType", "operator=() should take '%0 const&', '%0&&' or '%0'"},
77  {"cv", "operator=() should not be marked '%1'"}};
78 
79  const auto *Method = Result.Nodes.getNodeAs<CXXMethodDecl>("method");
80  for (const auto &Message : Messages) {
81  if (Result.Nodes.getNodeAs<Decl>(Message[0]))
82  diag(Method->getLocStart(), Message[1])
83  << Method->getParent()->getName()
84  << (Method->isConst() ? "const" : "virtual");
85  }
86  }
87 }
88 
89 } // namespace misc
90 } // namespace tidy
91 } // namespace clang
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:262
const NamedDecl * Result
Definition: USRFinder.cpp:162