https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113770
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Masahide Kashiwagi from comment #5) > Thank you very much. > > I understand that g++ 13 no longer supports _Float64x in a very limited way. You understand it wrong. _Float64x wasn't supported at all in GCC 12 and earlier. The reason you don't get an error is because of glibc typedefs. Now it is supported in a limited way. > Does this mean that if I want to use 80-bit extended floating point numbers > in g++ 13 or later, is it best to use long double? > > Since long double may not be 80-bit on non-x86 architectures, I wanted to > use _Float64x or __float80, which are clearly 80-bit, if possible. _Float64x certainly doesn't mean 80-bit. In C, it doesn't have to be supported at all (such as when IEEE double is the largest type supported by hw and/or emulation), or can be IEEE quad, 80-bit extended or whatever else. So, if you need only 80-bit and want an error otherwise, use __float80.
