https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91371
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- We already have 24 partial specializations. To handle ms_abi, fastcall and thiscall would need another 72. We could probably stamp them out with preprocessor macros, but I'd prefer not to. I think we need something smarter (either an __is_function(T) compiler builtin or something like libc++'s solution).
