From ffe3a6612f48c48d0d4ca285cf9833df87b6c240 Mon Sep 17 00:00:00 2001
From: jason <jason@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Thu, 11 Sep 2014 13:50:27 +0000
Subject: [PATCH] 	PR c++/63139 	* pt.c (tsubst_pack_expansion):
 Simplify substitution into T.... 	(tsubst): Don't throw away
 PACK_EXPANSION_EXTRA_ARGS.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@215171 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/cp/ChangeLog                         |  6 +++
 gcc/cp/pt.c                              | 11 ++++-
 gcc/testsuite/g++.dg/cpp0x/variadic161.C | 51 ++++++++++++++++++++++++
 3 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic161.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 565b940f0be9..7ebc56b63429 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2014-09-11  Jason Merrill  <jason@redhat.com>
+
+	PR c++/63139
+	* pt.c (tsubst_pack_expansion): Simplify substitution into T....
+	(tsubst): Don't throw away PACK_EXPANSION_EXTRA_ARGS.
+
 2014-09-10  Jason Merrill  <jason@redhat.com>
 
 	PR c++/61659
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 3c9317883eee..7f7ab9308903 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -9913,6 +9913,11 @@ 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));
+
   /* We cannot expand this expansion expression, because we don't have
      all of the argument packs we need.  */
   if (use_pack_expansion_extra_args_p (packs, len, unsubstituted_packs))
@@ -11831,7 +11836,11 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 		   gen_elem_of_pack_expansion_instantiation will
 		   build the resulting pack expansion from it.  */
 		if (PACK_EXPANSION_P (arg))
-		  arg = PACK_EXPANSION_PATTERN (arg);
+		  {
+		    /* Make sure we aren't throwing away arg info.  */
+		    gcc_assert (!PACK_EXPANSION_EXTRA_ARGS (arg));
+		    arg = PACK_EXPANSION_PATTERN (arg);
+		  }
 	      }
 	  }
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic161.C b/gcc/testsuite/g++.dg/cpp0x/variadic161.C
new file mode 100644
index 000000000000..ac6eaf6a36a5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic161.C
@@ -0,0 +1,51 @@
+// PR c++/63139
+// { dg-do compile { target c++11 } }
+
+template<typename ...T>
+struct type_list {};
+
+template<typename ...T>
+struct make_type_list
+{
+    using type = type_list<T...>;
+};
+
+// The bug disappears if you use make_type_list directly.
+template<typename ...T>
+using make_type_list_t = typename make_type_list<T...>::type;
+
+
+struct ContainerEndA {};
+
+template<typename ...Ts>
+struct ContainerA
+{
+    using type = make_type_list_t<Ts..., ContainerEndA>;
+};
+
+
+struct ContainerEndB {};
+
+template<typename ...Ts>
+struct ContainerB
+{
+    using type = make_type_list_t<Ts..., ContainerEndB>;
+};
+
+template<typename T, typename U>
+struct is_same
+{
+  static const bool value = false;
+};
+
+template<typename T>
+struct is_same<T, T>
+{
+  static const bool value = true;
+};
+
+#define SA(X) static_assert((X), #X)
+
+SA((is_same<ContainerB<>::type, type_list<ContainerEndB>>::value));
+SA((!is_same<ContainerA<>::type, type_list<ContainerEndB>>::value));
+SA((!is_same<ContainerA<>::type, ContainerB<>::type>::value));
-- 
2.47.2