From 559f2bbc362f311ab424232e72bb4f9f601b54eb Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Sun, 13 Nov 2016 01:52:43 -0500
Subject: [PATCH] CWG 2233 - default arg and parameter pack

	* typeck.c (convert_arguments): Handle default arg followed by none.

From-SVN: r242350
---
 gcc/cp/ChangeLog                         | 3 +++
 gcc/cp/typeck.c                          | 9 +++++++--
 gcc/testsuite/g++.dg/cpp0x/variadic169.C | 9 +++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/variadic169.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index b2195e4b687..8683744ad67 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,8 @@
 2016-11-12  Jason Merrill  <jason@redhat.com>
 
+	CWG 2233
+	* typeck.c (convert_arguments): Handle default arg followed by none.
+
 	* constexpr.c (potential_constant_expression_1): REALPART_EXPR and
 	IMAGPART_EXPR can be lvalues.
 
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 211696cf029..24ca1b52410 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -3835,6 +3835,10 @@ convert_arguments (tree typelist, vec<tree, va_gc> **values, tree fndecl,
 	{
 	  for (; typetail != void_list_node; ++i)
 	    {
+	      /* After DR777, with explicit template args we can end up with a
+		 default argument followed by no default argument.  */
+	      if (!TREE_PURPOSE (typetail))
+		break;
 	      tree parmval
 		= convert_default_arg (TREE_VALUE (typetail),
 				       TREE_PURPOSE (typetail),
@@ -3850,9 +3854,10 @@ convert_arguments (tree typelist, vec<tree, va_gc> **values, tree fndecl,
 		break;
 	    }
 	}
-      else
+
+      if (typetail && typetail != void_list_node)
 	{
-          if (complain & tf_error)
+	  if (complain & tf_error)
 	    error_args_num (input_location, fndecl, /*too_many_p=*/false);
 	  return -1;
 	}
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic169.C b/gcc/testsuite/g++.dg/cpp0x/variadic169.C
new file mode 100644
index 00000000000..6858973cd2e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic169.C
@@ -0,0 +1,9 @@
+// DR 2233
+// { dg-do compile { target c++11 } }
+
+template<typename ...T> void f(int n = 0, T ...t);
+
+int main()
+{
+  f<int>();			// { dg-error "too few arguments" }
+}
-- 
2.30.2