[HIP][OpenMP] Fix assertion in deferred diag

Fix assertion in UsedDeclVisitor where clang is trying to look up a destructor
for a forward declared class.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=52250

Reviewed by: Artem Belevich, John McCall

Differential Revision: https://reviews.llvm.org/D112235

clang/lib/Sema/UsedDeclVisitor.h

@@ -72,7 +72,8 @@ class UsedDeclVisitor : public EvaluatedExprVisitor<Derived> {
       QualType Destroyed = S.Context.getBaseElementType(DestroyedOrNull);
       if (const RecordType *DestroyedRec = Destroyed->getAs<RecordType>()) {
         CXXRecordDecl *Record = cast<CXXRecordDecl>(DestroyedRec->getDecl());
-        asImpl().visitUsedDecl(E->getBeginLoc(), S.LookupDestructor(Record));
+        if (Record->getDefinition())
+          asImpl().visitUsedDecl(E->getBeginLoc(), S.LookupDestructor(Record));
       }
     }
 

clang/test/OpenMP/deferred-diags.cpp

@@ -6,8 +6,6 @@
 // RUN:            -verify-ignore-unexpected=note \
 // RUN:            -fopenmp -o - %s
 
-// expected-no-diagnostics
-
 // Test no infinite recursion in DeferredDiagnosticEmitter.
 constexpr int foo(int *x) {
   return 0;
@@ -37,3 +35,14 @@ class A : public B {
      }
   }
 };
+
+// Test that deleting an incomplete class type doesn't cause an assertion.
+namespace TestDeleteIncompleteClassDefinition {
+struct a;
+struct b {
+  b() {
+    delete c; // expected-warning {{deleting pointer to incomplete type 'TestDeleteIncompleteClassDefinition::a' may cause undefined behavior}}
+  }
+  a *c;
+};
+} // namespace TestDeleteIncompleteClassDefinition