gcc/cp/
	* cp-tree.h (OVL_HIDDEN_P): New.
	(ovl_iterator::hidden_p, ovl_iterator::reveal_node): New.
	(ovl_iterator::reveal_node): Declare.
	* tree.c (ovl_copy): Copy OVL_HIDDEN_P.
	(ovl_insert): Order on hiddenness.
	(ovl_iterator::reveal_node): New.
	* name-lookup.c (anticipated_builtin_p): New.
	(supplement_binding_1): Use it.
	(set_local_extern_decl_linkage): Use hidden_p.
	(do_pushdecl): Deal with unhiding a hidden decl, use
	anticipated_builtin_p.
	(do_nonmember_using_decl): Use anticipated_decl_p.
	(lookup_name_real_1): Use DECL_HIDDEN_P.

	gcc/testsuite/
	* g++.dg/lookup/extern-c-hidden.C: New.
	* g++.dg/lookup/extern-redecl1.C: New.

From-SVN: r248406