Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 3 Nov 2022 15:07:37 +0100
From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
To:     Julia Lawall <julia.lawall@inria.fr>
Cc:     Kees Cook <keescook@chromium.org>, cocci@inria.fr,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        mm-commits@vger.kernel.org, masahiroy@kernel.org,
        gregkh@linuxfoundation.org, andriy.shevchenko@linux.intel.com,
        Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [cocci] [PATCH -mm] -funsigned-char, x86: make struct
 p4_event_bind::cntr signed array
Message-ID: <Y2PLKc1yeUTV4YFL@zx2c4.com>
References: <CAHmME9qBZqTd0D_gr8nE+DUzCrC0fxZNZK=7u+21jbgtFgAJBg@mail.gmail.com>
 <CAHk-=wjZDC9o8iwF+bU91Hx40HjGOpMui+VoFCDJkaGCu=rG4A@mail.gmail.com>
 <202210201151.ECC19BC97A@keescook>
 <Y1iSYddi3BpP8gvf@zx2c4.com>
 <Y1ku+jfRAyezq6Nz@zx2c4.com>
 <b72d866d-1dce-7260-7f1e-54be9fd25e97@inria.fr>
 <Y2MGlTwh9aB+4z4l@zx2c4.com>
 <d930b8af-7cb-c652-c3a4-cf8e9bdd610@inria.fr>
 <CAHmME9o3BDe+s2QaT4X8jg+9cc9A-3iHWnL0WnFyqKcGuhahXQ@mail.gmail.com>
 <8e7bcf3-2d39-a9f2-f818-ec627e5d5c4e@inria.fr>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <8e7bcf3-2d39-a9f2-f818-ec627e5d5c4e@inria.fr>
Precedence: bulk

On Thu, Nov 03, 2022 at 01:57:26PM +0100, Julia Lawall wrote:
> 
> 
> On Thu, 3 Nov 2022, Jason A. Donenfeld wrote:
> 
> > Hi Julia,
> >
> > On Thu, Nov 3, 2022 at 1:45 PM Julia Lawall <julia.lawall@inria.fr> wrote:
> > > It should work now.
> >
> > Thanks!
> >
> > > However, without disable optional_qualifier, char is
> > > still matching signed char.  If you think that should be changed, I can do
> > > that.
> >
> > Does `optional_qualifier` disable other things that might be
> > interesting to have? If so, maybe this is less than ideal? If not,
> > maybe it doesn't matter?
> 
> Optional qualifier only allows a metavariable declared to have a certain
> type to match an expression that has the same type with signed, const, or
> verbatim in front of it.  Disabling it forces you to write our signed,
> const etc explicitly when you want them.  So rules may becomes more
> verbose.

Oh, huh. Maybe best to treat it as a different type then so that's not
required? I was also thinking that it doesn't totally make sense the way
it is now, in that `char` is *NOT* signed on many platforms, such as
arm. In 6.2, it'll be unsigned everywhere, for kernel code. So in the
general case, for coccinelle, it's a bit of a heisentype and so maybe
should be treated as distinct from `signed char` or `unsigned char`.

Jason