clang-tools  8.0.0
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 "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/ASTMatchers/ASTMatchers.h"
13 #include "clang/Lex/Lexer.h"
14 #include "llvm/ADT/Optional.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.getBeginLoc(),
26  Param.getEndLoc().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  // Class template instantiations have a non-definition
40  // CXXMethodDecl for methods that aren't used in this
41  // translation unit. Ignore those, as the template will have
42  // already been checked.
43  unless(cxxMethodDecl(ofClass(cxxRecordDecl(anyOf(
44  isLambda(), ast_matchers::isTemplateInstantiation()))))),
45  has(typeLoc(forEach(ConstParamDecl))))
46  .bind("func"),
47  this);
48 }
49 
50 // Re-lex the tokens to get precise location of last 'const'
51 static llvm::Optional<Token> ConstTok(CharSourceRange Range,
52  const MatchFinder::MatchResult &Result) {
53  const SourceManager &Sources = *Result.SourceManager;
54  std::pair<FileID, unsigned> LocInfo =
55  Sources.getDecomposedLoc(Range.getBegin());
56  StringRef File = Sources.getBufferData(LocInfo.first);
57  const char *TokenBegin = File.data() + LocInfo.second;
58  Lexer RawLexer(Sources.getLocForStartOfFile(LocInfo.first),
59  Result.Context->getLangOpts(), File.begin(), TokenBegin,
60  File.end());
61  Token Tok;
62  llvm::Optional<Token> ConstTok;
63  while (!RawLexer.LexFromRawLexer(Tok)) {
64  if (Sources.isBeforeInTranslationUnit(Range.getEnd(), Tok.getLocation()))
65  break;
66  if (Tok.is(tok::raw_identifier)) {
67  IdentifierInfo &Info = Result.Context->Idents.get(StringRef(
68  Sources.getCharacterData(Tok.getLocation()), Tok.getLength()));
69  Tok.setIdentifierInfo(&Info);
70  Tok.setKind(Info.getTokenID());
71  }
72  if (Tok.is(tok::kw_const))
73  ConstTok = Tok;
74  }
75  return ConstTok;
76 }
77 
78 void AvoidConstParamsInDecls::check(const MatchFinder::MatchResult &Result) {
79  const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func");
80  const auto *Param = Result.Nodes.getNodeAs<ParmVarDecl>("param");
81 
82  if (!Param->getType().isLocalConstQualified())
83  return;
84 
85  auto Diag = diag(Param->getBeginLoc(),
86  "parameter %0 is const-qualified in the function "
87  "declaration; const-qualification of parameters only has an "
88  "effect in function definitions");
89  if (Param->getName().empty()) {
90  for (unsigned int i = 0; i < Func->getNumParams(); ++i) {
91  if (Param == Func->getParamDecl(i)) {
92  Diag << (i + 1);
93  break;
94  }
95  }
96  } else {
97  Diag << Param;
98  }
99 
100  if (Param->getBeginLoc().isMacroID() != Param->getEndLoc().isMacroID()) {
101  // Do not offer a suggestion if the part of the variable declaration comes
102  // from a macro.
103  return;
104  }
105 
106  CharSourceRange FileRange = Lexer::makeFileCharRange(
107  CharSourceRange::getTokenRange(getTypeRange(*Param)),
108  *Result.SourceManager, getLangOpts());
109 
110  if (!FileRange.isValid())
111  return;
112 
113  auto Tok = ConstTok(FileRange, Result);
114  if (!Tok)
115  return;
116  Diag << FixItHint::CreateRemoval(
117  CharSourceRange::getTokenRange(Tok->getLocation(), Tok->getLocation()));
118 }
119 
120 } // namespace readability
121 } // namespace tidy
122 } // namespace clang
static llvm::Optional< Token > ConstTok(CharSourceRange Range, const MatchFinder::MatchResult &Result)
llvm::Optional< llvm::Expected< tooling::AtomicChanges > > Result
FunctionInfo Info
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
CharSourceRange Range
SourceRange for the file name.