make ctype ascii only? (was [PATCH] kbuild: treat char as always signed)

[Rasmus Villemoes]

On 19/10/2022 21.54, Linus Torvalds wrote:
> On Wed, Oct 19, 2022 at 9:27 AM Jason A. Donenfeld <Jason@xxxxxxxxx> wrote:
>>
>> So let's just eliminate this particular variety of heisensigned bugs
>> entirely. Set `-fsigned-char` globally, so that gcc makes the type
>> signed on all architectures.
> 
> Btw, I do wonder if we might actually be better off doing this - but
> doing it the other way around.

Only very tangentially related (because it has to do with chars...): Can
we switch our ctype to be ASCII only, just as it was back in the good'ol
mid 90s [i.e. before
https://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux-fullhistory.git/commit/lib/ctype.c?id=036b97b05489161be06e63be77c5fad9247d23ff].

It bugs me that it's almost-but-not-quite-latin1, that toupper() isn't
idempotent, and that one can hit an isalpha() with toupper() and get
something that isn't isalpha().

Rasmus