Index: clang/lib/Sema/SemaLookup.cpp
===================================================================
--- clang/lib/Sema/SemaLookup.cpp
+++ clang/lib/Sema/SemaLookup.cpp
@@ -2820,6 +2820,13 @@
     case Type::Record: {
       CXXRecordDecl *Class =
           cast<CXXRecordDecl>(cast<RecordType>(T)->getDecl());
+      // Class needs to be a complete type.
+      if (Class->getTemplateSpecializationKind() == TSK_Undeclared &&
+          Result.InstantiationLoc.isInvalid()) {
+        Result.S.RequireCompleteType(Class->getLocation(),
+                                     Result.S.Context.getRecordType(Class),
+                                     diag::err_incomplete_type);
+      }
       addAssociatedClassesAndNamespaces(Result, Class);
       break;
     }
Index: clang/test/SemaCXX/template-specialization.cpp
===================================================================
--- clang/test/SemaCXX/template-specialization.cpp
+++ clang/test/SemaCXX/template-specialization.cpp
@@ -19,3 +19,16 @@
   B::foo<4>(); // expected-note {{in instantiation of function template specialization 'B::foo<4>'}}
   return 0;
 }
+
+template <typename T>
+struct z {
+  static void aj() {
+    T f;
+#pragma omp target map(f)
+    ;
+  }
+};
+
+template <typename> class ar {};
+template <int> struct as {};
+template class z<ar<as<4>>>;