[Bug preprocessor/79948] _Pragma(“GCC error”) is processed differently inside and outside of a #if directive

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79948

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I have not read the standard in this area but I know somethings are interesting
in this area that most folks won't expect.  Inside #if undefined macros are
considered as 0.