[Bug preprocessor/62661] digit separator warning in if'ed out code

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62661

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
What's really fun is that you can't even do:

#if __cpp_digit_separators
int i = 1'000;
#else
int i = 1000;
#endif