[Bug c++/59480] Missing error diagnostic: friend declaration specifying a default argument must be a definition

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59480

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> ---
See also http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#136