[Bug libstdc++/96279] build failure: floating_from_chars.cc:310:22: error: '__builtin_isinf_sign' is not a member of 'std'

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96279

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
looks like a bogus #define leaking in from somewhere.  Maybe you can provide
preprocessed source with -dD (that preserves #define directives in the output)