[clang-tidy] fix false positive for implicit conversion of comparison result in C23 (#113639)

Fixed #111013
bool will be builtin type in C23 but comparison result in C is still
int.
It is no need to change this kind of implicit cast to explicit cast.

Author: HerrCai0907

clang-tools-extra/clang-tidy/readability/ImplicitBoolConversionCheck.cpp

@@ -10,6 +10,7 @@
 #include "../utils/FixItHintUtils.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Tooling/FixIt.h"
 #include <queue>
@@ -26,6 +27,8 @@ AST_MATCHER(Stmt, isMacroExpansion) {
   return SM.isMacroBodyExpansion(Loc) || SM.isMacroArgExpansion(Loc);
 }
 
+AST_MATCHER(Stmt, isC23) { return Finder->getASTContext().getLangOpts().C23; }
+
 bool isNULLMacroExpansion(const Stmt *Statement, ASTContext &Context) {
   SourceManager &SM = Context.getSourceManager();
   const LangOptions &LO = Context.getLangOpts();
@@ -298,6 +301,11 @@ void ImplicitBoolConversionCheck::registerMatchers(MatchFinder *Finder) {
                          hasCastKind(CK_FloatingToBoolean),
                          hasCastKind(CK_PointerToBoolean),
                          hasCastKind(CK_MemberPointerToBoolean)),
+                   // Exclude cases of C23 comparison result.
+                   unless(allOf(isC23(),
+                                hasSourceExpression(ignoringParens(
+                                    binaryOperator(hasAnyOperatorName(
+                                        ">", ">=", "==", "!=", "<", "<=")))))),
                    // Exclude case of using if or while statements with variable
                    // declaration, e.g.:
                    //   if (int var = functionCall()) {}

clang-tools-extra/docs/ReleaseNotes.rst

@@ -249,7 +249,8 @@ Changes in existing checks
 - Improved :doc:`readability-implicit-bool-conversion
   <clang-tidy/checks/readability/implicit-bool-conversion>` check
   by adding the option `UseUpperCaseLiteralSuffix` to select the
-  case of the literal suffix in fixes.
+  case of the literal suffix in fixes and fixing false positive for implicit
+  conversion of comparison result in C23.
 
 - Improved :doc:`readability-redundant-smartptr-get
   <clang-tidy/checks/readability/redundant-smartptr-get>` check to

clang-tools-extra/test/clang-tidy/checkers/readability/implicit-bool-conversion.c

@@ -304,6 +304,15 @@ void implicitConversionToBoolFromUnaryMinusAndZeroLiterals() {
   // CHECK-FIXES: functionTakingBool((-0.0) != 0.0);
 }
 
+void ignoreImplicitCastToBoolForComparisonResult() {
+  bool boolFromComparison0 = 1 != 0;
+  bool boolFromComparison1 = 1 == 0;
+  bool boolFromComparison2 = 1 > 0;
+  bool boolFromComparison3 = 1 >= 0;
+  bool boolFromComparison4 = 1 < 0;
+  bool boolFromComparison5 = 1 <= 0;
+}
+
 void ignoreExplicitCastsToBool() {
   int integer = 10;
   bool boolComingFromInt = (bool)integer;