[clang] Fix unexpected -Wconstant-logical-operand in C23

[Fznamznon]

C23 has bool, but logical operators still return int. Double check that we're not in C23 to avoid false-positive -Wconstant-logical-operand.

Fixes #64356

[llvmbot]

@llvm/pr-subscribers-clang

Author: Mariya Podchishchaeva (Fznamznon)

Changes

C23 has bool, but logical operators still return int. Double check that we're not in C23 to avoid false-positive -Wconstant-logical-operand.

Fixes #64356

---

Full diff: https://github.com/llvm/llvm-project/pull/80724.diff

2 Files Affected:

• (modified) clang/lib/Sema/SemaExpr.cpp (+2-1)
• (modified) clang/test/Sema/warn-int-in-bool-context.c (+11)

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index d15278bce5a6ba..f65b3abe5eaa24 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14073,7 +14073,8 @@ inline QualType Sema::CheckLogicalOperands(ExprResult &LHS, ExprResult &RHS,
     Expr::EvalResult EVResult;
     if (RHS.get()->EvaluateAsInt(EVResult, Context)) {
       llvm::APSInt Result = EVResult.Val.getInt();
-      if ((getLangOpts().Bool && !RHS.get()->getType()->isBooleanType() &&
+      if ((getLangOpts().Bool && !getLangOpts().C23 &&
+           !RHS.get()->getType()->isBooleanType() &&
            !RHS.get()->getExprLoc().isMacroID()) ||
           (Result != 0 && Result != 1)) {
         Diag(Loc, diag::warn_logical_instead_of_bitwise)
diff --git a/clang/test/Sema/warn-int-in-bool-context.c b/clang/test/Sema/warn-int-in-bool-context.c
index a6890161b5af89..c111a5af23f577 100644
--- a/clang/test/Sema/warn-int-in-bool-context.c
+++ b/clang/test/Sema/warn-int-in-bool-context.c
@@ -79,3 +79,14 @@ int test(int a, unsigned b, enum num n) {
   // Don't warn in macros.
   return SHIFT(1, a);
 }
+
+int GH64356(int arg) {
+  if ((arg == 1) && (1 == 1)) return 1;
+    return 0;
+
+  if ((64 > 32) && (32 < 64))
+    return 2;
+
+  if ((1 == 1) && (arg == 1)) return 1;
+    return 0;
+}

[AaronBallman]

LGTM though you should add a release note before landing. I think this is a good one to backport into Clang 18.x given how simple the fix is.

Thank you!

[efriedma-quic]

We probably shouldn't be checking for getLangOpts().Bool here at all; as documented in LangOptions.def, that flag is only supposed to indicate whether "bool" is a keyword. getLangOpts().CPlusPlus is probably appropriate.

[AaronBallman]

LGTM, thank you!

[Fznamznon]

Windows failure in CI seems unrelated.