PR c++/80244 - ICE with attribute in template alias.

	* tree.c (strip_typedefs): Handle UNDERLYING_TYPE.

	* g++.dg/cpp0x/alias-decl-59.C: New test.

From-SVN: r246962

gcc/cp/ChangeLog

+2017-04-18  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/80244 - ICE with attribute in template alias.
+	* tree.c (strip_typedefs): Handle UNDERLYING_TYPE.
+
 2017-04-17  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	PR c++/80287

gcc/cp/tree.c

@@ -1551,6 +1551,10 @@ strip_typedefs (tree t, bool *remove_attributes)
 		   DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t),
 		   tf_none));
       break;
+    case UNDERLYING_TYPE:
+      type = strip_typedefs (UNDERLYING_TYPE_TYPE (t), remove_attributes);
+      result = finish_underlying_type (type);
+      break;
     default:
       break;
     }

gcc/testsuite/ChangeLog

+2017-04-18  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/80244 - ICE with attribute in template alias.
+	* g++.dg/cpp0x/alias-decl-59.C: New test.
+
 2017-04-17  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	PR c++/80287

gcc/testsuite/g++.dg/cpp0x/alias-decl-59.C

+// PR c++/80244
+// { dg-do compile { target c++11 } }
+
+template<typename>
+struct A {};
+
+template<typename T>
+using B = A<__underlying_type(T) [[gnu::aligned(4)]]>; // { dg-warning "ignoring attributes on template argument" }
+
+template<typename T>
+using B = A<__underlying_type(T) [[gnu::packed]]>; // { dg-warning "ignoring attributes on template argument" }