re PR c++/39863 ([c++0x] variadic templates : wrong error "mismatched argument pack lengths")

	PR c++/39863
	* pt.c (tsubst_pack_expansion): Don't do anything now if we
	have incomplete packs of different lengths.

From-SVN: r152537

gcc/cp/ChangeLog

 2009-10-07  Jason Merrill  <jason@redhat.com>
 
+	PR c++/39863
+	* pt.c (tsubst_pack_expansion): Don't do anything now if we
+	have incomplete packs of different lengths.
+
 	PR c++/41038
 	* tree.c (build_qualified_name): Call convert_from_reference.
 

gcc/cp/pt.c

@@ -7944,6 +7944,10 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain,
             }
           else if (len != my_len)
             {
+	      if (incomplete)
+		/* We got explicit args for some packs but not others;
+		   do nothing now and try again after deduction.  */
+		return t;
               if (TREE_CODE (t) == TYPE_PACK_EXPANSION)
                 error ("mismatched argument pack lengths while expanding "
                        "%<%T%>",

gcc/testsuite/ChangeLog

 2009-10-07  Jason Merrill  <jason@redhat.com>
 
+	* g++.dg/cpp0x/variadic95.C: New.
+
+2009-10-07  Jason Merrill  <jason@redhat.com>
+
 	* g++.dg/template/scope3.C: New.
 
 2009-10-07  Jakub Jelinek  <jakub@redhat.com>

gcc/testsuite/g++.dg/cpp0x/variadic95.C

+// PR c++/39863
+// { dg-options -std=c++0x }
+
+template <typename... T>
+struct A {};
+
+template <typename T, typename U>
+struct S {};
+
+template <typename... T, typename... U>
+A< S<T, U>... > f(U... u)
+{ return A< S<T, U>... >(); }
+
+int main()
+{
+  f<int>(0.0);
+}