https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113770
--- Comment #3 from Masahide Kashiwagi <kashi at waseda dot jp> --- I forgot to mention in my earlier post that these two programs work fine in g++ 12. Also, at https://gcc.gnu.org/onlinedocs/gcc/Floating-Types.html it says that __float80 and _Float64x are 80-bit extended floating point numbers and are available on x86. Has support for _Float64x been stopped?