https://github.com/Aadarsh-Keshri created https://github.com/llvm/llvm-project/pull/181169
### Summary Fix a crash for _Countof(void) caused by incorrect extension handling in CheckExtensionTraitOperandType. Fixes #180893 >From 112655ff9a52df366e3cb7b3316435cf6a160842 Mon Sep 17 00:00:00 2001 From: Aadarsh-Keshri <[email protected]> Date: Thu, 12 Feb 2026 20:48:12 +0530 Subject: [PATCH] [Clang] Fix crash for _Countof(void) by correcting extension handling --- clang/lib/Sema/SemaExpr.cpp | 31 ++++++++++++++++--------------- clang/test/C/C2y/n3369.c | 2 ++ 2 files changed, 18 insertions(+), 15 deletions(-) diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 233f9ff297608..1d16962cd9b5f 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -4225,24 +4225,25 @@ static bool CheckExtensionTraitOperandType(Sema &S, QualType T, return true; // C99 6.5.3.4p1: - if (T->isFunctionType() && - (TraitKind == UETT_SizeOf || TraitKind == UETT_AlignOf || - TraitKind == UETT_PreferredAlignOf)) { + if (TraitKind == UETT_SizeOf || TraitKind == UETT_AlignOf || + TraitKind == UETT_PreferredAlignOf) { + // sizeof(function)/alignof(function) is allowed as an extension. - S.Diag(Loc, diag::ext_sizeof_alignof_function_type) - << getTraitSpelling(TraitKind) << ArgRange; - return false; - } + if (T->isFunctionType()) { + S.Diag(Loc, diag::ext_sizeof_alignof_function_type) + << getTraitSpelling(TraitKind) << ArgRange; + return false; + } - // Allow sizeof(void)/alignof(void) as an extension, unless in OpenCL where - // this is an error (OpenCL v1.1 s6.3.k) - if (T->isVoidType()) { - unsigned DiagID = S.LangOpts.OpenCL ? diag::err_opencl_sizeof_alignof_type - : diag::ext_sizeof_alignof_void_type; - S.Diag(Loc, DiagID) << getTraitSpelling(TraitKind) << ArgRange; - return false; + // Allow sizeof(void)/alignof(void) as an extension, unless in OpenCL where + // this is an error (OpenCL v1.1 s6.3.k) + if (T->isVoidType()) { + unsigned DiagID = S.LangOpts.OpenCL ? diag::err_opencl_sizeof_alignof_type + : diag::ext_sizeof_alignof_void_type; + S.Diag(Loc, DiagID) << getTraitSpelling(TraitKind) << ArgRange; + return false; + } } - return true; } diff --git a/clang/test/C/C2y/n3369.c b/clang/test/C/C2y/n3369.c index dd3125709279d..eee723bbb33b7 100644 --- a/clang/test/C/C2y/n3369.c +++ b/clang/test/C/C2y/n3369.c @@ -35,6 +35,8 @@ void test_semantic_failures() { int non_array; (void)_Countof non_array; // expected-error {{'_Countof' requires an argument of array type; 'int' invalid}} (void)_Countof(int); // expected-error {{'_Countof' requires an argument of array type; 'int' invalid}} + (void)_Countof(void); // expected-error {{invalid application of '_Countof' to an incomplete type 'void'}} + int arr2[_Countof(void)]; // expected-error {{invalid application of '_Countof' to an incomplete type 'void'}} (void)_Countof(test_semantic_failures); // expected-error {{invalid application of '_Countof' to a function type}} (void)_Countof(struct S); // expected-error {{invalid application of '_Countof' to an incomplete type 'struct S'}} \ expected-note {{forward declaration of 'struct S'}} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
