[OpenMP][clang] Fix CaptureRegion for message clause (#156525)

Fixes llvm/llvm-project#156232

Author: ro-i

clang/lib/Sema/SemaOpenMP.cpp

@@ -16479,9 +16479,13 @@ OMPClause *SemaOpenMP::ActOnOpenMPMessageClause(Expr *ME,
 
   Stmt *HelperValStmt = nullptr;
 
+  // Depending on whether this clause appears in an executable context or not,
+  // we may or may not build a capture.
   OpenMPDirectiveKind DKind = DSAStack->getCurrentDirective();
-  OpenMPDirectiveKind CaptureRegion = getOpenMPCaptureRegionForClause(
-      DKind, OMPC_message, getLangOpts().OpenMP);
+  OpenMPDirectiveKind CaptureRegion =
+      DKind == OMPD_unknown ? OMPD_unknown
+                            : getOpenMPCaptureRegionForClause(
+                                  DKind, OMPC_message, getLangOpts().OpenMP);
   if (CaptureRegion != OMPD_unknown &&
       !SemaRef.CurContext->isDependentContext()) {
     ME = SemaRef.MakeFullExpr(ME).get();

clang/test/OpenMP/error_message.cpp

@@ -4,6 +4,9 @@
 // RUN: %clang_cc1 -verify -fopenmp-simd -fopenmp-version=51 -ferror-limit 100 %s -Wuninitialized
 // RUN: %clang_cc1 -verify -fopenmp-simd -fopenmp-version=60 -ferror-limit 100 %s -Wuninitialized
 
+// Test outside of an executable context.
+#pragma omp error severity(warning) message("msg") at(compilation) // expected-warning {{msg}}
+
 template <class T>
 T tmain(T argc) {
   if (argc)