This is an odd testcase, but we were only rejecting it by accident.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit d248b59f755fd2071a27209e034610396c947809
Author: Jason Merrill <ja...@redhat.com>
Date: Tue Apr 16 11:59:34 2013 +0100
Core 1609
* decl2.c (check_default_args): Check for pack expansion.
diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index 74e51a8..8d2385d 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -4463,7 +4463,7 @@ check_default_args (tree x)
{
if (TREE_PURPOSE (arg))
saw_def = true;
- else if (saw_def)
+ else if (saw_def && !PACK_EXPANSION_P (TREE_VALUE (arg)))
{
error ("default argument missing for parameter %P of %q+#D", i, x);
TREE_PURPOSE (arg) = error_mark_node;
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic142.C b/gcc/testsuite/g++.dg/cpp0x/variadic142.C
new file mode 100644
index 0000000..83b2429
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic142.C
@@ -0,0 +1,9 @@
+// Core 1609
+// { dg-require-effective-target c++11 }
+
+template<typename... T>
+void f2(int a = 0, T... b, int c = 1);
+
+int main(){
+ f2<>(); // parameter a has the value 0 and parameter c has the value 1
+}
