https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59342
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Seems fixed in GCC 6+ (but I can't figure out what fixed it).
[Bug c++/59342] Function Template Specialisation causing compiler error together with using clauses
pinskia at gcc dot gnu.org via Gcc-bugs Tue, 03 Aug 2021 23:52:48 -0700
