https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119217
--- Comment #7 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot
Uni-Bielefeld.DE> ---
The _Float128 handling is completely unportable, it turns out:
#if ! (__HAVE_FLOAT128 && __GLIBC_USE (IEC_60559_TYPES_EXT))
__HAVE_FLOAT128 is a glibc-internal macro, as is __GLIBC_USE. On top of
that, the fallback code providing strfromf128 is unportable in itself:
it uses strfroml, which is a C23 addition apparently. I don't think we
can reasonably require C23 support on the host.
Besides, both libstd++ and libgfortran already provide fallback code to
handle this situation:
cf. libstdc++-v3/src/c++17/floating_{from,to}_chars.cc and
libgfortran/io/{read.c,write_float.def}.
