From bc7f13bf15c30ee57601c3ec0c8390cfc15e01db Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Wed, 25 May 2011 10:32:06 -0400
Subject: [PATCH] re PR c++/48292 ([C++0x] "sorry, unimplemented: use of
 'type_pack_expansion' in template")

	PR c++/48292
	* pt.c (tsubst_decl) [PARM_DECL]: Handle partial instantiation of
	function parameter pack.
	(tsubst_pack_expansion): Likewise.

From-SVN: r174201
---
 gcc/cp/ChangeLog                         |  5 +++++
 gcc/cp/pt.c                              | 15 ++++++++++-----
 gcc/testsuite/ChangeLog                  |  4 ++++
 gcc/testsuite/g++.dg/cpp0x/variadic109.C | 17 +++++++++++++++++
 4 files changed, 36 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic109.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index fc9b883f637..57321507c81 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,10 @@
 2011-05-25  Jason Merrill  <jason@redhat.com>
 
+	PR c++/48292
+	* pt.c (tsubst_decl) [PARM_DECL]: Handle partial instantiation of
+	function parameter pack.
+	(tsubst_pack_expansion): Likewise.
+
 	* cp-objcp-common.c (cp_common_init_ts): TYPE_ARGUMENT_PACK has
 	TS_COMMON.
 
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index bd9aeba91b8..fc84314daaf 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -8711,7 +8711,12 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
 		 have the wrong value for a recursive call.  Just make a
 		 dummy decl, since it's only used for its type.  */
 	      arg_pack = tsubst_decl (parm_pack, args, complain);
-	      arg_pack = make_fnparm_pack (arg_pack);
+	      if (arg_pack && FUNCTION_PARAMETER_PACK_P (arg_pack))
+		/* Partial instantiation of the parm_pack, we can't build
+		   up an argument pack yet.  */
+		arg_pack = NULL_TREE;
+	      else
+		arg_pack = make_fnparm_pack (arg_pack);
 	    }
 	}
       else
@@ -9801,14 +9806,14 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain)
             if (DECL_TEMPLATE_PARM_P (t))
               SET_DECL_TEMPLATE_PARM_P (r);
 
-	    /* An argument of a function parameter pack is not a parameter
-	       pack.  */
-	    FUNCTION_PARAMETER_PACK_P (r) = false;
-
             if (expanded_types)
               /* We're on the Ith parameter of the function parameter
                  pack.  */
               {
+		/* An argument of a function parameter pack is not a parameter
+		   pack.  */
+		FUNCTION_PARAMETER_PACK_P (r) = false;
+
                 /* Get the Ith type.  */
                 type = TREE_VEC_ELT (expanded_types, i);
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4258b91106c..9f13b0d7573 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2011-05-25  Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/cpp0x/variadic109.C: New.
+
 2011-05-25  H.J. Lu  <hongjiu.lu@intel.com>
 
 	 * gcc.target/i386/pause-1.c: New.
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic109.C b/gcc/testsuite/g++.dg/cpp0x/variadic109.C
new file mode 100644
index 00000000000..0ec69af812e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic109.C
@@ -0,0 +1,17 @@
+// PR c++/48292
+// { dg-options -std=c++0x }
+
+template <typename... Args> int g(Args...);
+
+template <int N = 0>
+struct A
+{
+    template <typename... Args>
+    static auto f(Args... args) -> decltype(g(args...));
+};
+
+int main()
+{
+    A<>::f();
+    return 0;
+}