re PR c++/63405 (ICE in cp_perform_integral_promotions, at cp/typeck.c:2084)

	PR c++/63405
	* pt.c (tsubst_pack_expansion): Limit simple expansion to type packs.

From-SVN: r216013

gcc/cp/ChangeLog

 2014-10-08  Jason Merrill  <jason@redhat.com>
 
+	PR c++/63405
+	* pt.c (tsubst_pack_expansion): Limit simple expansion to type packs.
+
 	PR c++/63485
 	* tree.c (build_cplus_array_type): Look for a type with no
 	typedef-name or attributes.

gcc/cp/pt.c

@@ -9929,7 +9929,13 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
   /* If the expansion is just T..., return the matching argument pack.  */
   if (!unsubstituted_packs
       && TREE_PURPOSE (packs) == pattern)
-    return ARGUMENT_PACK_ARGS (TREE_VALUE (packs));
+    {
+      tree args = ARGUMENT_PACK_ARGS (TREE_VALUE (packs));
+      if (TREE_CODE (t) == TYPE_PACK_EXPANSION
+	  || pack_expansion_args_count (args))
+	return args;
+      /* Otherwise use the normal path so we get convert_from_reference.  */
+    }
 
   /* We cannot expand this expansion expression, because we don't have
      all of the argument packs we need.  */

gcc/testsuite/g++.dg/cpp0x/variadic162.C

+// PR c++/63405
+// { dg-do compile { target c++11 } }
+
+template <typename _Tp> _Tp forward(_Tp);
+template <typename Args> struct Format { Format(int, Args); };
+template <typename... Args> auto format(Args &&... args) -> Format<Args...> {
+  return {0, args...};
+}
+
+template <typename... Args> void msg(Args... args) {
+  format(forward(args)...);
+}
+
+void some_function() { msg('x'); }