https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111058
--- Comment #7 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- There shouldn't be such a thing as an unsupported constant payload; both __builtin_nan and __builtin_nans should rather be made consistent with parsing of payloads by glibc's nan functions (that may in some cases mean changing glibc; see https://sourceware.org/bugzilla/show_bug.cgi?id=28322 - glibc's functions don't handle payloads wider than 64 bits for _Float128, but GCC's do).
