clang-tools  3.9.0
AvoidConstParamsInDecls.cpp
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1 //===--- AvoidConstParamsInDecls.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 
11 #include "llvm/ADT/Optional.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/ASTMatchers/ASTMatchers.h"
14 #include "clang/Lex/Lexer.h"
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace readability {
21 namespace {
22 
23 SourceRange getTypeRange(const ParmVarDecl &Param) {
24  if (Param.getIdentifier() != nullptr)
25  return SourceRange(Param.getLocStart(),
26  Param.getLocEnd().getLocWithOffset(-1));
27  return Param.getSourceRange();
28 }
29 
30 } // namespace
31 
32 void AvoidConstParamsInDecls::registerMatchers(MatchFinder *Finder) {
33  const auto ConstParamDecl =
34  parmVarDecl(hasType(qualType(isConstQualified()))).bind("param");
35  Finder->addMatcher(
36  functionDecl(unless(isDefinition()),
37  // Lambdas are always their own definition, but they
38  // generate a non-definition FunctionDecl too. Ignore those.
39  unless(cxxMethodDecl(ofClass(cxxRecordDecl(isLambda())))),
40  has(typeLoc(forEach(ConstParamDecl))))
41  .bind("func"),
42  this);
43 }
44 
45 // Re-lex the tokens to get precise location of last 'const'
46 static llvm::Optional<Token> ConstTok(CharSourceRange Range,
47  const MatchFinder::MatchResult &Result) {
48  const SourceManager &Sources = *Result.SourceManager;
49  std::pair<FileID, unsigned> LocInfo =
50  Sources.getDecomposedLoc(Range.getBegin());
51  StringRef File = Sources.getBufferData(LocInfo.first);
52  const char *TokenBegin = File.data() + LocInfo.second;
53  Lexer RawLexer(Sources.getLocForStartOfFile(LocInfo.first),
54  Result.Context->getLangOpts(), File.begin(), TokenBegin,
55  File.end());
56  Token Tok;
57  llvm::Optional<Token> ConstTok;
58  while (!RawLexer.LexFromRawLexer(Tok)) {
59  if (Sources.isBeforeInTranslationUnit(Range.getEnd(), Tok.getLocation()))
60  break;
61  if (Tok.is(tok::raw_identifier)) {
62  IdentifierInfo &Info = Result.Context->Idents.get(StringRef(
63  Sources.getCharacterData(Tok.getLocation()), Tok.getLength()));
64  Tok.setIdentifierInfo(&Info);
65  Tok.setKind(Info.getTokenID());
66  }
67  if (Tok.is(tok::kw_const))
68  ConstTok = Tok;
69  }
70  return ConstTok;
71 }
72 
73 void AvoidConstParamsInDecls::check(const MatchFinder::MatchResult &Result) {
74  const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func");
75  const auto *Param = Result.Nodes.getNodeAs<ParmVarDecl>("param");
76 
77  if (!Param->getType().isLocalConstQualified())
78  return;
79 
80  auto Diag = diag(Param->getLocStart(),
81  "parameter %0 is const-qualified in the function "
82  "declaration; const-qualification of parameters only has an "
83  "effect in function definitions");
84  if (Param->getName().empty()) {
85  for (unsigned int i = 0; i < Func->getNumParams(); ++i) {
86  if (Param == Func->getParamDecl(i)) {
87  Diag << (i + 1);
88  break;
89  }
90  }
91  } else {
92  Diag << Param;
93  }
94 
95  if (Param->getLocStart().isMacroID() != Param->getLocEnd().isMacroID()) {
96  // Do not offer a suggestion if the part of the variable declaration comes
97  // from a macro.
98  return;
99  }
100 
101  CharSourceRange FileRange = Lexer::makeFileCharRange(
102  CharSourceRange::getTokenRange(getTypeRange(*Param)),
103  *Result.SourceManager, Result.Context->getLangOpts());
104 
105  if (!FileRange.isValid())
106  return;
107 
108  auto Tok = ConstTok(FileRange, Result);
109  if (!Tok)
110  return;
111  Diag << FixItHint::CreateRemoval(
112  CharSourceRange::getTokenRange(Tok->getLocation(), Tok->getLocation()));
113 }
114 
115 } // namespace readability
116 } // namespace tidy
117 } // namespace clang
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:210
HeaderHandle File
static llvm::Optional< Token > ConstTok(CharSourceRange Range, const MatchFinder::MatchResult &Result)
CharSourceRange Range
SourceRange for the file name.
const NamedDecl * Result
Definition: USRFinder.cpp:137