https://gcc.gnu.org/ml/gcc-patches/2017-12/msg01168.html
	PR c++/59930
	* name-lookup.c (name_lookup::search_unqualified): Don't search
	parent namespace when looking for hidden things.
	* pt.c (tsubst_friend_class): Always push to friend scope, drop
	unneeded self-friend check. Inject new hidden friend into correct
	scope.

	PR c++/59930
	* g++.dg/parse/pr81247-c.C: Adjust.
	* g++.dg/template/pr59930-[123].C: New.

From-SVN: r255780