c++: hidden friend access [DR1699]

c++: hidden friend access [DR1699]

It has come up several times that Clang considers hidden friends of a class
to be sufficiently memberly to be covered by a friend declaration naming the
class.  This is somewhat unclear in the standard: [class.friend] says
"Declaring a class to be a friend implies that private and protected members
of the class granting friendship can be named in the base-specifiers and
member declarations of the befriended class."

A hidden friend is a syntactic member-declaration, but is it a "member
declaration"?  CWG was ambivalent, and referred the question to EWG as a
design choice.  But recently Patrick mentioned that the current G++ choice
not to treat it as a "member declaration" was making his library work
significantly more cumbersome, so let's go ahead and vote the other way.

This means that the testcases for 100502 and 58993 are now accepted.

	DR1699
	PR c++/100502
	PR c++/58993

gcc/cp/ChangeLog:

	* friend.cc (is_friend): Hidden friends count as members.
	* search.cc (friend_accessible_p): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/template/access37.C: Now OK.
	* g++.dg/template/friend69.C: Now OK.
	* g++.dg/lookup/friend23.C: New test.