https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81279
--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> --- GCC before 7.1 had a bug where it would think all _call were template functions while inside the template function _call. So now GCC does the correct thing and does not think that. So before trying calling the non template form of _call would not have worked.
