[clang-tools-extra] [clang-tidy] Catch <cctype> function args in bugprone-signed-char-misuse (PR #211403)

[via cfe-commits]

================
@@ -138,8 +165,7 @@ void SignedCharMisuseCheck::check(const MatchFinder::MatchResult &Result) {
   // The potential misinterpretation happens for negative values only.
   Expr::EvalResult EVResult;
   if (!SignedCastExpression->isValueDependent() &&
-      SignedCastExpression->getSubExpr()->EvaluateAsInt(EVResult,
-                                                        *Result.Context)) {
+      SignedCastExpression->EvaluateAsInt(EVResult, *Result.Context)) {
----------------
cavdarahmet wrote:

Confirmed and fixed — thanks for catching this, it was a real regression. The shared `check()` path is now identical to `main` again (both `getSubExpr()->EvaluateAsInt()` calls restored); the cctype case binds a separate `cctypeArgument` node and is handled in an isolated early-return branch, exactly as you suggested. Your example is now a regression test, plus a constexpr-negative test for the new path.


https://github.com/llvm/llvm-project/pull/211403