From fd8b207a76d9a1eb8cc8e3c2f81b13391bd41310 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Mon, 25 Jul 2016 15:10:41 -0400
Subject: [PATCH] PR c++/71833 - member template with two parameter packs

	PR c++/54440
	* pt.c (coerce_template_parameter_pack): Fix logic for
	pack index.

From-SVN: r238731
---
 gcc/cp/ChangeLog                              | 5 +++++
 gcc/cp/pt.c                                   | 7 ++++---
 gcc/testsuite/g++.dg/cpp0x/variadic-nested1.C | 9 +++++++++
 3 files changed, 18 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic-nested1.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 5854205b3b7..9ae7e67eb21 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,10 @@
 2016-07-25  Jason Merrill  <jason@redhat.com>
 
+	PR c++/71833
+	PR c++/54440
+	* pt.c (coerce_template_parameter_pack): Fix logic for
+	pack index.
+
 	PR c++/65970
 	* constexpr.c (cxx_eval_loop_expr): Count iterations.
 	* cp-gimplify.c (genericize_cp_loop): Use start_locus even for
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index a61f1c81a19..7dd6b25931d 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -7403,11 +7403,12 @@ coerce_template_parameter_pack (tree parms,
 
   /* Convert the remaining arguments, which will be a part of the
      parameter pack "parm".  */
+  int first_pack_arg = arg_idx;
   for (; arg_idx < nargs; ++arg_idx)
     {
       tree arg = TREE_VEC_ELT (inner_args, arg_idx);
       tree actual_parm = TREE_VALUE (parm);
-      int pack_idx = arg_idx - parm_idx;
+      int pack_idx = arg_idx - first_pack_arg;
 
       if (packed_parms)
         {
@@ -7436,12 +7437,12 @@ coerce_template_parameter_pack (tree parms,
       TREE_VEC_ELT (packed_args, pack_idx) = arg;
     }
 
-  if (arg_idx - parm_idx < TREE_VEC_LENGTH (packed_args)
+  if (arg_idx - first_pack_arg < TREE_VEC_LENGTH (packed_args)
       && TREE_VEC_LENGTH (packed_args) > 0)
     {
       if (complain & tf_error)
 	error ("wrong number of template arguments (%d, should be %d)",
-	       arg_idx - parm_idx, TREE_VEC_LENGTH (packed_args));
+	       arg_idx - first_pack_arg, TREE_VEC_LENGTH (packed_args));
       return error_mark_node;
     }
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic-nested1.C b/gcc/testsuite/g++.dg/cpp0x/variadic-nested1.C
new file mode 100644
index 00000000000..abfb49a712c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic-nested1.C
@@ -0,0 +1,9 @@
+// PR c++/71833
+// { dg-do compile { target c++11 } }
+
+template < typename ... Ts > struct A 
+{
+  template < Ts ..., typename ... Us > struct B {};
+};
+
+A <>::B < int > e;