clang-tools  10.0.0svn
RedundantPreprocessorCheck.cpp
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1 //===--- RedundantPreprocessorCheck.cpp - clang-tidy ----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
10 #include "clang/Frontend/CompilerInstance.h"
11 
12 namespace clang {
13 namespace tidy {
14 namespace readability {
15 
16 namespace {
17 /// Information about an opening preprocessor directive.
18 struct PreprocessorEntry {
19  SourceLocation Loc;
20  /// Condition used after the preprocessor directive.
21  std::string Condition;
22 };
23 
24 class RedundantPreprocessorCallbacks : public PPCallbacks {
25  enum DirectiveKind { DK_If = 0, DK_Ifdef = 1, DK_Ifndef = 2 };
26 
27 public:
28  explicit RedundantPreprocessorCallbacks(ClangTidyCheck &Check,
29  Preprocessor &PP)
30  : Check(Check), PP(PP),
31  WarningDescription("nested redundant %select{#if|#ifdef|#ifndef}0; "
32  "consider removing it"),
33  NoteDescription("previous %select{#if|#ifdef|#ifndef}0 was here") {}
34 
35  void If(SourceLocation Loc, SourceRange ConditionRange,
36  ConditionValueKind ConditionValue) override {
37  StringRef Condition =
38  Lexer::getSourceText(CharSourceRange::getTokenRange(ConditionRange),
39  PP.getSourceManager(), PP.getLangOpts());
40  CheckMacroRedundancy(Loc, Condition, IfStack, DK_If, DK_If, true);
41  }
42 
43  void Ifdef(SourceLocation Loc, const Token &MacroNameTok,
44  const MacroDefinition &MacroDefinition) override {
45  std::string MacroName = PP.getSpelling(MacroNameTok);
46  CheckMacroRedundancy(Loc, MacroName, IfdefStack, DK_Ifdef, DK_Ifdef, true);
47  CheckMacroRedundancy(Loc, MacroName, IfndefStack, DK_Ifdef, DK_Ifndef,
48  false);
49  }
50 
51  void Ifndef(SourceLocation Loc, const Token &MacroNameTok,
52  const MacroDefinition &MacroDefinition) override {
53  std::string MacroName = PP.getSpelling(MacroNameTok);
54  CheckMacroRedundancy(Loc, MacroName, IfndefStack, DK_Ifndef, DK_Ifndef,
55  true);
56  CheckMacroRedundancy(Loc, MacroName, IfdefStack, DK_Ifndef, DK_Ifdef,
57  false);
58  }
59 
60  void Endif(SourceLocation Loc, SourceLocation IfLoc) override {
61  if (!IfStack.empty() && IfLoc == IfStack.back().Loc)
62  IfStack.pop_back();
63  if (!IfdefStack.empty() && IfLoc == IfdefStack.back().Loc)
64  IfdefStack.pop_back();
65  if (!IfndefStack.empty() && IfLoc == IfndefStack.back().Loc)
66  IfndefStack.pop_back();
67  }
68 
69 private:
70  void CheckMacroRedundancy(SourceLocation Loc, StringRef MacroName,
71  SmallVector<PreprocessorEntry, 4> &Stack,
72  DirectiveKind WarningKind, DirectiveKind NoteKind,
73  bool Store) {
74  if (PP.getSourceManager().isInMainFile(Loc)) {
75  for (const auto &Entry : Stack) {
76  if (Entry.Condition == MacroName) {
77  Check.diag(Loc, WarningDescription) << WarningKind;
78  Check.diag(Entry.Loc, NoteDescription, DiagnosticIDs::Note)
79  << NoteKind;
80  }
81  }
82  }
83 
84  if (Store)
85  // This is an actual directive to be remembered.
86  Stack.push_back({Loc, MacroName});
87  }
88 
89  ClangTidyCheck &Check;
90  Preprocessor &PP;
91  SmallVector<PreprocessorEntry, 4> IfStack;
92  SmallVector<PreprocessorEntry, 4> IfdefStack;
93  SmallVector<PreprocessorEntry, 4> IfndefStack;
94  const std::string WarningDescription;
95  const std::string NoteDescription;
96 };
97 } // namespace
98 
100  const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
101  PP->addPPCallbacks(
102  ::std::make_unique<RedundantPreprocessorCallbacks>(*this, *PP));
103 }
104 
105 } // namespace readability
106 } // namespace tidy
107 } // namespace clang
SourceLocation Loc
clang::tok::PPKeywordKind DirectiveKind
Location Loc
Definition: Modularize.cpp:438
llvm::Optional< Range > getTokenRange(const SourceManager &SM, const LangOptions &LangOpts, SourceLocation TokLoc)
Returns the taken range at TokLoc.
Definition: SourceCode.cpp:229
clang::PPCallbacks::ConditionValueKind ConditionValue
void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) override
Override this to register PPCallbacks in the preprocessor.
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
std::string Condition
Condition used after the preprocessor directive.