https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99708
--- Comment #3 from Segher Boessenkool <segher at gcc dot gnu.org> --- The only such __SIZEOF_* macro that is not about a standards-required type is for int128. Not the best example ;-) There are not predefines for __SIZEOF_FLOAT128__ etc. either. In an ideal world the user can just assume those types exist always. In a less ideal world, use autoconf? You have to anyway, if you want to support older compilers at all.
