C++ PATCH for c++/49420 (ICE printing variadic error context)

C++ PATCH for c++/49420 (ICE printing variadic error context)

[Jason Merrill]

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With ENABLE_CHECKING we want to make sure that we're tracking the number 
of non-default template arguments, but that doesn't apply to argument packs.

Tested x86_64-pc-linux-gnu, applying to trunk.

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commit 8ed2e06bbc3925a1c8d86641938f83e9bbd15bda
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Jun 15 12:24:17 2011 -0400

    	PR c++/49420
    	* error.c (dump_template_argument): Don't try to omit default
    	template args from an argument pack.

diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index 22470dc..7c90ec4 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -147,7 +147,9 @@ static void
 dump_template_argument (tree arg, int flags)
 {
   if (ARGUMENT_PACK_P (arg))
-    dump_template_argument_list (ARGUMENT_PACK_ARGS (arg), flags);
+    dump_template_argument_list (ARGUMENT_PACK_ARGS (arg),
+				 /* No default args in argument packs.  */
+				 flags|TFF_NO_OMIT_DEFAULT_TEMPLATE_ARGUMENTS);
   else if (TYPE_P (arg) || TREE_CODE (arg) == TEMPLATE_DECL)
     dump_type (arg, flags & ~TFF_CLASS_KEY_OR_ENUM);
   else
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic112.C b/gcc/testsuite/g++.dg/cpp0x/variadic112.C
new file mode 100644
index 0000000..1640657
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic112.C
@@ -0,0 +1,19 @@
+// PR c++/49420
+// { dg-options -std=c++0x }
+
+struct A { };
+
+template <class T> struct B
+{
+  typedef typename T::type type ; // { dg-error "no type" }
+};
+
+template <typename Array, typename... Args>
+typename B<Array>::type
+get(const Array& a, Args... args);
+
+int main()
+{
+  A a;
+  int x = get(a, 1, 2, 3);	// { dg-error "no match" }
+}