https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109936
--- Comment #26 from Adam Wozniak <adam at wozniakconsulting dot com> ---
(In reply to Jonathan Wakely from comment #19)
> (In reply to Andreas Schwab from comment #10)
> > It is a valid preprocessing token ("non-whitespace character that cannot be
> > one of the above").
>
> Ah right, yes. It's a preprocessing token, but is never converted to a
> token, so doesn't need to be a keyword, identifier etc.
i feel like it should work for stringification reasons too. e.g.
#define X(x) #x
const char *letterA = X(A); // this works
const char *notequal = X(≠); // this does not
