https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109818
--- Comment #8 from Janez Zemva <janezz55 at gmail dot com> --- I took a look and I believe the c_global is already being selected and I believe the hack I presented should perhaps be applied to libstdc++-v3/include/c_global/cmath - the hack template is in there. As for the other hacks/patches - I am not the author of any of them. The author(s) never bothered to report any bugs and I doubt they ever will. The patches are very old and they change incrementally, whenever something in gcc changes.
