Index: gcc/tree.c
===================================================================
--- gcc/tree.c	(revision 163581)
+++ gcc/tree.c	(working copy)
@@ -10508,7 +10508,7 @@
 /* Return true if TYPE has a variable argument list.  */
 
 bool
-stdarg_p (tree fntype)
+stdarg_p (const_tree fntype)
 {
   function_args_iterator args_iter;
   tree n = NULL_TREE, t;
Index: gcc/tree.h
===================================================================
--- gcc/tree.h	(revision 163581)
+++ gcc/tree.h	(working copy)
@@ -4767,16 +4767,14 @@
 
 /* Iterator for going through the function arguments.  */
 typedef struct {
-  tree fntype;			/* function type declaration */
   tree next;			/* TREE_LIST pointing to the next argument */
 } function_args_iterator;
 
 /* Initialize the iterator I with arguments from function FNDECL  */
 
 static inline void
-function_args_iter_init (function_args_iterator *i, tree fntype)
+function_args_iter_init (function_args_iterator *i, const_tree fntype)
 {
-  i->fntype = fntype;
   i->next = TYPE_ARG_TYPES (fntype);
 }
 
@@ -4848,7 +4846,7 @@
 extern tree *call_expr_argp (tree, int);
 extern tree create_artificial_label (location_t);
 extern const char *get_name (tree);
-extern bool stdarg_p (tree);
+extern bool stdarg_p (const_tree);
 extern bool prototype_p (tree);
 extern bool is_typedef_decl (tree x);
 extern bool typedef_variant_p (tree);