https://gcc.gnu.org/bugzilla/show_bug.cgi?id=45881
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2763.pdf It seems like they did not add this ... But they do have _Bitwidthof now ...
