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
9 #include "RedundantPreprocessorCheck.h"
10 #include "clang/Frontend/CompilerInstance.h"
11 #include "clang/Lex/Lexer.h"
12 #include "clang/Lex/PPCallbacks.h"
13 #include "clang/Lex/Preprocessor.h"
14
15 namespace clang {
16 namespace tidy {
17 namespace readability {
18
19 namespace {
20 /// Information about an opening preprocessor directive.
21 struct PreprocessorEntry {
22 SourceLocation Loc;
23 /// Condition used after the preprocessor directive.
24 std::string Condition;
25 };
26
27 const char WarningDescription[] =
28 "nested redundant %select{#if|#ifdef|#ifndef}0; consider removing it";
29 const char NoteDescription[] = "previous %select{#if|#ifdef|#ifndef}0 was here";
30
31 class RedundantPreprocessorCallbacks : public PPCallbacks {
32 enum DirectiveKind { DK_If = 0, DK_Ifdef = 1, DK_Ifndef = 2 };
33
34 public:
RedundantPreprocessorCallbacks(ClangTidyCheck & Check,Preprocessor & PP)35 explicit RedundantPreprocessorCallbacks(ClangTidyCheck &Check,
36 Preprocessor &PP)
37 : Check(Check), PP(PP) {}
38
If(SourceLocation Loc,SourceRange ConditionRange,ConditionValueKind ConditionValue)39 void If(SourceLocation Loc, SourceRange ConditionRange,
40 ConditionValueKind ConditionValue) override {
41 StringRef Condition =
42 Lexer::getSourceText(CharSourceRange::getTokenRange(ConditionRange),
43 PP.getSourceManager(), PP.getLangOpts());
44 checkMacroRedundancy(Loc, Condition, IfStack, DK_If, DK_If, true);
45 }
46
Ifdef(SourceLocation Loc,const Token & MacroNameTok,const MacroDefinition & MacroDefinition)47 void Ifdef(SourceLocation Loc, const Token &MacroNameTok,
48 const MacroDefinition &MacroDefinition) override {
49 std::string MacroName = PP.getSpelling(MacroNameTok);
50 checkMacroRedundancy(Loc, MacroName, IfdefStack, DK_Ifdef, DK_Ifdef, true);
51 checkMacroRedundancy(Loc, MacroName, IfndefStack, DK_Ifdef, DK_Ifndef,
52 false);
53 }
54
Ifndef(SourceLocation Loc,const Token & MacroNameTok,const MacroDefinition & MacroDefinition)55 void Ifndef(SourceLocation Loc, const Token &MacroNameTok,
56 const MacroDefinition &MacroDefinition) override {
57 std::string MacroName = PP.getSpelling(MacroNameTok);
58 checkMacroRedundancy(Loc, MacroName, IfndefStack, DK_Ifndef, DK_Ifndef,
59 true);
60 checkMacroRedundancy(Loc, MacroName, IfdefStack, DK_Ifndef, DK_Ifdef,
61 false);
62 }
63
Endif(SourceLocation Loc,SourceLocation IfLoc)64 void Endif(SourceLocation Loc, SourceLocation IfLoc) override {
65 if (!IfStack.empty() && IfLoc == IfStack.back().Loc)
66 IfStack.pop_back();
67 if (!IfdefStack.empty() && IfLoc == IfdefStack.back().Loc)
68 IfdefStack.pop_back();
69 if (!IfndefStack.empty() && IfLoc == IfndefStack.back().Loc)
70 IfndefStack.pop_back();
71 }
72
73 private:
checkMacroRedundancy(SourceLocation Loc,StringRef MacroName,SmallVector<PreprocessorEntry,4> & Stack,DirectiveKind WarningKind,DirectiveKind NoteKind,bool Store)74 void checkMacroRedundancy(SourceLocation Loc, StringRef MacroName,
75 SmallVector<PreprocessorEntry, 4> &Stack,
76 DirectiveKind WarningKind, DirectiveKind NoteKind,
77 bool Store) {
78 if (PP.getSourceManager().isInMainFile(Loc)) {
79 for (const auto &Entry : Stack) {
80 if (Entry.Condition == MacroName) {
81 Check.diag(Loc, WarningDescription) << WarningKind;
82 Check.diag(Entry.Loc, NoteDescription, DiagnosticIDs::Note)
83 << NoteKind;
84 }
85 }
86 }
87
88 if (Store)
89 // This is an actual directive to be remembered.
90 Stack.push_back({Loc, std::string(MacroName)});
91 }
92
93 ClangTidyCheck &Check;
94 Preprocessor &PP;
95 SmallVector<PreprocessorEntry, 4> IfStack;
96 SmallVector<PreprocessorEntry, 4> IfdefStack;
97 SmallVector<PreprocessorEntry, 4> IfndefStack;
98 };
99 } // namespace
100
registerPPCallbacks(const SourceManager & SM,Preprocessor * PP,Preprocessor * ModuleExpanderPP)101 void RedundantPreprocessorCheck::registerPPCallbacks(
102 const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
103 PP->addPPCallbacks(
104 ::std::make_unique<RedundantPreprocessorCallbacks>(*this, *PP));
105 }
106
107 } // namespace readability
108 } // namespace tidy
109 } // namespace clang
110