================
@@ -0,0 +1,123 @@
+//===--- TrueMacroCheck.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 "TrueMacroCheck.h"
+#include "clang/Lex/MacroInfo.h"
+#include "clang/Lex/PPCallbacks.h"
+#include "clang/Lex/Preprocessor.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+namespace {
+
+class MacroCallback : public PPCallbacks {
+ static constexpr const char *TrueMacroSpelling = "true";
+
+public:
+ MacroCallback(TrueMacroCheck *Check, Preprocessor *PP)
+ : Check(Check), PP(PP) {}
+ void MacroDefined(const Token &MacroNameTok,
+ const MacroDirective *MD) override {
+ if (TrueDefined)
+ return;
+
+ const MacroInfo *MI = MD->getMacroInfo();
+ for (const Token &Tok : MI->tokens()) {
+ if (PP->getSpelling(Tok) == TrueMacroSpelling)
+ emitDiagnostics(Tok.getLocation(),
+ {Tok.getLocation(), Tok.getEndLoc()});
+ }
+
+ if (PP->getSpelling(MacroNameTok) == TrueMacroSpelling)
+ TrueDefined = true;
+ }
+
+ virtual void MacroUndefined(const Token &MacroNameTok,
+ const MacroDefinition &MD,
+ const MacroDirective *Undef) override {
+ if (PP->getSpelling(MacroNameTok) == TrueMacroSpelling)
+ TrueDefined = false;
+ }
+
+ virtual void If(SourceLocation Loc, SourceRange ConditionRange,
+ ConditionValueKind ConditionValue) override {
+ StringRef Condition =
+ Lexer::getSourceText(CharSourceRange::getTokenRange(ConditionRange),
+ PP->getSourceManager(), PP->getLangOpts());
+
+ if (!TrueDefined && Condition == TrueMacroSpelling) {
+ emitDiagnostics(ConditionRange.getBegin(), ConditionRange);
+ return;
+ }
+
+ for (auto &&Identifier : identifiersInCondition(Condition)) {
+ if (!TrueDefined && Identifier == TrueMacroSpelling) {
+ emitDiagnostics(Loc, {}, true);
+ break;
+ }
+ }
+ }
+
+private:
+ void emitDiagnostics(SourceLocation Loc, SourceRange ReplaceRange,
+ bool InCondition = false) {
+ DiagnosticBuilder Builder =
+ Check->diag(Loc, "in C 'true'%select{| in the condition}0 is treated "
+ "as an undefined "
+ "macro and evaluates to a falsy value; "
+ "consider replacing it with '1'")
+ << InCondition;
+
+ if (!InCondition)
+ Builder << FixItHint::CreateReplacement(ReplaceRange, "1");
+ }
+
+ std::vector<StringRef> identifiersInCondition(StringRef Condition) {
+ const static auto Start = [](char C) {
+ return C == '_' || ('a' <= C && C <= 'z') || ('A' <= C && C <= 'Z');
+ };
+
+ const static auto Continue = [](char C) {
+ return ('0' <= C && C <= '9') || Start(C);
+ };
+
+ std::vector<StringRef> Identifiers;
+ const char *Str = nullptr;
+
+ for (size_t I = 0; I < Condition.size(); ++I) {
+ char C = Condition[I];
----------------
EugeneZelenko wrote:
```suggestion
const char C = Condition[I];
```
https://github.com/llvm/llvm-project/pull/128265
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