https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65434
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> --- Please send patches to the libstdc++@ and gcc-patches@ mailing lists, rather than attaching them to closed bugs. https://gcc.gnu.org/onlinedocs/libstdc++/manual/appendix_contributing.html