[Bug c++/42328] rejects valid friend

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42328

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Clang accepts the code in comment 0, but GCC 4.9 and icc 13.0.1 still give the
same errors as stated here in 2009