https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94080
There is a HUGE amount of work to do to make libstdc++ support it properly. I think I've already done most of it, but last time I tried to test it everything failed because glibc didn't have the necessary ieee long double support yet. I should check if it's landed in glibc yet and resurrect that git branch.
