re PR c++/40751 (G++ never packs typedef'd enums)

	PR c++/40751
	PR c++/64987
	* decl.c (copy_type_enum): Respect TYPE_USER_ALIGN.

From-SVN: r232702

gcc/cp/ChangeLog

 2016-01-21  Jason Merrill  <jason@redhat.com>
 
+	PR c++/40751
+	PR c++/64987
+	* decl.c (copy_type_enum): Respect TYPE_USER_ALIGN.
+
 	PR c++/43407
 	* decl.c (start_enum): Add attributes parameter.
 	* parser.c (cp_parser_enum_specifier): Pass it.

gcc/cp/decl.c

@@ -13030,8 +13030,12 @@ copy_type_enum (tree dst, tree src)
       TYPE_SIZE_UNIT (t) = TYPE_SIZE_UNIT (src);
       SET_TYPE_MODE (dst, TYPE_MODE (src));
       TYPE_PRECISION (t) = TYPE_PRECISION (src);
-      TYPE_ALIGN (t) = TYPE_ALIGN (src);
-      TYPE_USER_ALIGN (t) = TYPE_USER_ALIGN (src);
+      unsigned valign = TYPE_ALIGN (src);
+      if (TYPE_USER_ALIGN (t))
+	valign = MAX (valign, TYPE_ALIGN (t));
+      else
+	TYPE_USER_ALIGN (t) = TYPE_USER_ALIGN (src);
+      TYPE_ALIGN (t) = valign;
       TYPE_UNSIGNED (t) = TYPE_UNSIGNED (src);
     }
 }

gcc/testsuite/g++.dg/cpp0x/alignas5.C

+// { dg-do compile { target c++11 } }
+
+#define SA(X) static_assert(X,#X)
+
+enum alignas(16) E {};
+SA(alignof(E) == 16);