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//===--- RedundantPreprocessorCheck.cpp - clang-tidy ----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "RedundantPreprocessorCheck.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Lex/Lexer.h"
#include "clang/Lex/PPCallbacks.h"
#include "clang/Lex/Preprocessor.h"
namespace clang::tidy::readability {
namespace {
/// Information about an opening preprocessor directive.
struct PreprocessorEntry {
SourceLocation Loc;
/// Condition used after the preprocessor directive.
std::string Condition;
};
const char WarningDescription[] =
"nested redundant %select{#if|#ifdef|#ifndef}0; consider removing it";
const char NoteDescription[] = "previous %select{#if|#ifdef|#ifndef}0 was here";
class RedundantPreprocessorCallbacks : public PPCallbacks {
enum DirectiveKind { DK_If = 0, DK_Ifdef = 1, DK_Ifndef = 2 };
public:
explicit RedundantPreprocessorCallbacks(ClangTidyCheck &Check,
Preprocessor &PP)
: Check(Check), PP(PP) {}
void If(SourceLocation Loc, SourceRange ConditionRange,
ConditionValueKind ConditionValue) override {
StringRef Condition =
Lexer::getSourceText(CharSourceRange::getTokenRange(ConditionRange),
PP.getSourceManager(), PP.getLangOpts());
checkMacroRedundancy(Loc, Condition, IfStack, DK_If, DK_If, true);
}
void Ifdef(SourceLocation Loc, const Token &MacroNameTok,
const MacroDefinition &MacroDefinition) override {
std::string MacroName = PP.getSpelling(MacroNameTok);
checkMacroRedundancy(Loc, MacroName, IfdefStack, DK_Ifdef, DK_Ifdef, true);
checkMacroRedundancy(Loc, MacroName, IfndefStack, DK_Ifdef, DK_Ifndef,
false);
}
void Ifndef(SourceLocation Loc, const Token &MacroNameTok,
const MacroDefinition &MacroDefinition) override {
std::string MacroName = PP.getSpelling(MacroNameTok);
checkMacroRedundancy(Loc, MacroName, IfndefStack, DK_Ifndef, DK_Ifndef,
true);
checkMacroRedundancy(Loc, MacroName, IfdefStack, DK_Ifndef, DK_Ifdef,
false);
}
void Endif(SourceLocation Loc, SourceLocation IfLoc) override {
if (!IfStack.empty() && IfLoc == IfStack.back().Loc)
IfStack.pop_back();
if (!IfdefStack.empty() && IfLoc == IfdefStack.back().Loc)
IfdefStack.pop_back();
if (!IfndefStack.empty() && IfLoc == IfndefStack.back().Loc)
IfndefStack.pop_back();
}
private:
void checkMacroRedundancy(SourceLocation Loc, StringRef MacroName,
SmallVector<PreprocessorEntry, 4> &Stack,
DirectiveKind WarningKind, DirectiveKind NoteKind,
bool Store) {
if (PP.getSourceManager().isInMainFile(Loc)) {
for (const auto &Entry : Stack) {
if (Entry.Condition == MacroName) {
Check.diag(Loc, WarningDescription) << WarningKind;
Check.diag(Entry.Loc, NoteDescription, DiagnosticIDs::Note)
<< NoteKind;
}
}
}
if (Store)
// This is an actual directive to be remembered.
Stack.push_back({Loc, std::string(MacroName)});
}
ClangTidyCheck &Check;
Preprocessor &PP;
SmallVector<PreprocessorEntry, 4> IfStack;
SmallVector<PreprocessorEntry, 4> IfdefStack;
SmallVector<PreprocessorEntry, 4> IfndefStack;
};
} // namespace
void RedundantPreprocessorCheck::registerPPCallbacks(
const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
PP->addPPCallbacks(
::std::make_unique<RedundantPreprocessorCallbacks>(*this, *PP));
}
} // namespace clang::tidy::readability
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