Index: test/Import/enum/Inputs/S.cpp
===================================================================
--- test/Import/enum/Inputs/S.cpp
+++ test/Import/enum/Inputs/S.cpp
@@ -2,3 +2,5 @@
   a = 1,
   b = 2
 };
+
+enum OpaqueWithType : long;
Index: test/Import/enum/test.cpp
===================================================================
--- test/Import/enum/test.cpp
+++ test/Import/enum/test.cpp
@@ -1,4 +1,8 @@
-// RUN: clang-import-test -import %S/Inputs/S.cpp -expression %s
+// RUN: clang-import-test -dump-ast -import %S/Inputs/S.cpp -expression %s | FileCheck %s
+
+// CHECK: OpaqueWithType 'long'
+
 void expr() {
   static_assert(E::a + E::b == 3);
+  static_assert(sizeof(OpaqueWithType) == sizeof(long));
 }