clang-tools  5.0.0
PostfixOperatorCheck.cpp
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1 //===--- PostfixOperatorCheck.cpp - clang-tidy-----------------------------===//
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 
10 #include "PostfixOperatorCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/Lex/Lexer.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace tidy {
19 namespace cert {
20 
21 void PostfixOperatorCheck::registerMatchers(MatchFinder *Finder) {
22  if (!getLangOpts().CPlusPlus)
23  return;
24 
25  Finder->addMatcher(functionDecl(anyOf(hasOverloadedOperatorName("++"),
26  hasOverloadedOperatorName("--")))
27  .bind("decl"),
28  this);
29 }
30 
31 void PostfixOperatorCheck::check(const MatchFinder::MatchResult &Result) {
32  const auto *FuncDecl = Result.Nodes.getNodeAs<FunctionDecl>("decl");
33 
34  bool HasThis = false;
35  if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FuncDecl))
36  HasThis = MethodDecl->isInstance();
37 
38  // Check if the operator is a postfix one.
39  if (FuncDecl->getNumParams() != (HasThis ? 1 : 2))
40  return;
41 
42  SourceRange ReturnRange = FuncDecl->getReturnTypeSourceRange();
43  SourceLocation Location = ReturnRange.getBegin();
44  if (!Location.isValid())
45  return;
46 
47  QualType ReturnType = FuncDecl->getReturnType();
48 
49  // Warn when the operators return a reference.
50  if (const auto *RefType = ReturnType->getAs<ReferenceType>()) {
51  auto Diag = diag(Location, "overloaded %0 returns a reference instead of a "
52  "constant object type")
53  << FuncDecl;
54 
55  if (Location.isMacroID() || ReturnType->getAs<TypedefType>() ||
56  RefType->getPointeeTypeAsWritten()->getAs<TypedefType>())
57  return;
58 
59  QualType ReplaceType =
60  ReturnType.getNonReferenceType().getLocalUnqualifiedType();
61  // The getReturnTypeSourceRange omits the qualifiers. We do not want to
62  // duplicate the const.
63  if (!ReturnType->getPointeeType().isConstQualified())
64  ReplaceType.addConst();
65 
66  Diag << FixItHint::CreateReplacement(
67  ReturnRange,
68  ReplaceType.getAsString(Result.Context->getPrintingPolicy()) + " ");
69 
70  return;
71  }
72 
73  if (ReturnType.isConstQualified() || ReturnType->isBuiltinType() ||
74  ReturnType->isPointerType())
75  return;
76 
77  auto Diag =
78  diag(Location, "overloaded %0 returns a non-constant object instead of a "
79  "constant object type")
80  << FuncDecl;
81 
82  if (!Location.isMacroID() && !ReturnType->getAs<TypedefType>())
83  Diag << FixItHint::CreateInsertion(Location, "const ");
84 }
85 
86 } // namespace cert
87 } // namespace tidy
88 } // namespace clang
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:275