https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118058
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- Hmm, I think this is a documentation issue at least. Would introducing a "NaN" literal as result of L'e' and then eliding all the compares as "WTF" (true or false?) work? Or maybe we need sth like #if __literal_supported (L'e') (or builtin, in case it's the frontend and not the preprocessor doing the translation)