Index: tree.c
===================================================================
--- tree.c	(revision 161914)
+++ tree.c	(working copy)
@@ -7350,7 +7350,7 @@
    if (TREE_CODE (orig_type) != METHOD_TYPE
        || !bitmap_bit_p (args_to_skip, 0))
      {
-      new_type = copy_node (orig_type);
+      new_type = build_distinct_type_copy (orig_type);
        TYPE_ARG_TYPES (new_type) = new_reversed;
      }
    else