[clang][OpenMP] Avoid null deref in allocator classification; diagnose missing <omp.h> in (fixes #157868)

Author: KrxGu

clang/lib/Sema/SemaOpenMP.cpp

@@ -3321,9 +3321,9 @@ SemaOpenMP::CheckOMPThreadPrivateDecl(SourceLocation Loc,
   }
   return D;
 }
-
 static OMPAllocateDeclAttr::AllocatorTypeTy
 getAllocatorKind(Sema &S, DSAStackTy *Stack, Expr *Allocator) {
+  // No allocator expression → Null mem alloc.
   if (!Allocator)
     return OMPAllocateDeclAttr::OMPNullMemAlloc;
   if (Allocator->isTypeDependent() || Allocator->isValueDependent() ||
@@ -3337,6 +3337,8 @@ getAllocatorKind(Sema &S, DSAStackTy *Stack, Expr *Allocator) {
   for (int I = 0; I < OMPAllocateDeclAttr::OMPUserDefinedMemAlloc; ++I) {
     auto AllocatorKind = static_cast<OMPAllocateDeclAttr::AllocatorTypeTy>(I);
     const Expr *DefAllocator = Stack->getAllocator(AllocatorKind);
+    if (!DefAllocator)
+      continue; // null-guard: predefined not populated
     llvm::FoldingSetNodeID DAEId;
     DefAllocator->IgnoreImpCasts()->Profile(DAEId, S.getASTContext(),
                                             /*Canonical=*/true);

clang/test/OpenMP/allocate-allocator-duplicate.c

@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fopenmp -verify %s
+
+typedef enum omp_allocator_handle_t {
+  omp_default_mem_alloc = 1,
+  __omp_allocator_handle_t_max__ = __UINTPTR_MAX__
+} omp_allocator_handle_t;
+
+void foo(void) {
+  omp_allocator_handle_t my_handle;
+  int A[2];
+  // expected-error@+2 {{'omp_allocator_handle_t' type not found; include <omp.h>}}
+  // expected-note@+1 {{previous allocator is specified here}}
+  #pragma omp allocate(A) allocator(my_handle)
+  // expected-warning@+1 {{allocate directive specifies 'my_handle' allocator while previously used default}}
+  #pragma omp allocate(A) allocator(my_handle)
+}

clang/test/OpenMP/allocate-allocator-handle-diag.c

@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -fopenmp -verify %s
+// No <omp.h>; forge a typedef.
+typedef enum omp_allocator_handle_t {
+  omp_default_mem_alloc = 1,
+  __omp_allocator_handle_t_max__ = __UINTPTR_MAX__
+} omp_allocator_handle_t;
+
+void foo(void) {
+  omp_allocator_handle_t my_handle;
+  int A[2];
+  // expected-error@+1 {{'omp_allocator_handle_t' type not found; include <omp.h>}}
+  #pragma omp allocate(A) allocator(my_handle)
+}