clang-tools  8.0.0
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  unless(isInstantiated()))
28  .bind("decl"),
29  this);
30 }
31 
32 void PostfixOperatorCheck::check(const MatchFinder::MatchResult &Result) {
33  const auto *FuncDecl = Result.Nodes.getNodeAs<FunctionDecl>("decl");
34 
35  bool HasThis = false;
36  if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FuncDecl))
37  HasThis = MethodDecl->isInstance();
38 
39  // Check if the operator is a postfix one.
40  if (FuncDecl->getNumParams() != (HasThis ? 1 : 2))
41  return;
42 
43  SourceRange ReturnRange = FuncDecl->getReturnTypeSourceRange();
44  SourceLocation Location = ReturnRange.getBegin();
45  if (!Location.isValid())
46  return;
47 
48  QualType ReturnType = FuncDecl->getReturnType();
49 
50  // Warn when the operators return a reference.
51  if (const auto *RefType = ReturnType->getAs<ReferenceType>()) {
52  auto Diag = diag(Location, "overloaded %0 returns a reference instead of a "
53  "constant object type")
54  << FuncDecl;
55 
56  if (Location.isMacroID() || ReturnType->getAs<TypedefType>() ||
57  RefType->getPointeeTypeAsWritten()->getAs<TypedefType>())
58  return;
59 
60  QualType ReplaceType =
61  ReturnType.getNonReferenceType().getLocalUnqualifiedType();
62  // The getReturnTypeSourceRange omits the qualifiers. We do not want to
63  // duplicate the const.
64  if (!ReturnType->getPointeeType().isConstQualified())
65  ReplaceType.addConst();
66 
67  Diag << FixItHint::CreateReplacement(
68  ReturnRange,
69  ReplaceType.getAsString(Result.Context->getPrintingPolicy()) + " ");
70 
71  return;
72  }
73 
74  if (ReturnType.isConstQualified() || ReturnType->isBuiltinType() ||
75  ReturnType->isPointerType())
76  return;
77 
78  auto Diag =
79  diag(Location, "overloaded %0 returns a non-constant object instead of a "
80  "constant object type")
81  << FuncDecl;
82 
83  if (!Location.isMacroID() && !ReturnType->getAs<TypedefType>())
84  Diag << FixItHint::CreateInsertion(Location, "const ");
85 }
86 
87 } // namespace cert
88 } // namespace tidy
89 } // namespace clang
llvm::Optional< llvm::Expected< tooling::AtomicChanges > > Result
std::string ReturnType
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//