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

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Message-ID: <3a2fa7c1-2e31-0479-761f-9c189f8ed8c3@rasmusvillemoes.dk>
Date:   Wed, 26 Oct 2022 02:10:02 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-toolchains@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: make ctype ascii only? (was [PATCH] kbuild: treat char as always
 signed)

On 19/10/2022 21.54, Linus Torvalds wrote:
> On Wed, Oct 19, 2022 at 9:27 AM Jason A. Donenfeld <Jason@...c4.com> 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