linux-kernel - Re: [PATCH] gpiolib: acpi: use correct format characters

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Message-ID: <CAGG=3QXJ1P-9vAvONe8PKBzMe3se66GSL9gbA9UoLb7a5R33kA@mail.gmail.com>
Date:   Fri, 18 Mar 2022 11:33:36 -0700
From:   Bill Wendling <morbo@...gle.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Nathan Chancellor <nathan@...nel.org>,
        linux-gpio@...r.kernel.org, linux-acpi@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>, llvm@...ts.linux.dev,
        Joe Perches <joe@...ches.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] gpiolib: acpi: use correct format characters

On Fri, Mar 18, 2022 at 11:29 AM Nick Desaulniers
<ndesaulniers@...gle.com> wrote:
>
> On Fri, Mar 18, 2022 at 11:25 AM Bill Wendling <morbo@...gle.com> wrote:
> >
> > On Fri, Mar 18, 2022 at 11:01 AM Nick Desaulniers
> > <ndesaulniers@...gle.com> wrote:
> > >
> > > On Fri, Mar 18, 2022 at 7:04 AM Andy Shevchenko
> > > <andriy.shevchenko@...ux.intel.com> wrote:
> > > >
> > > > On Thu, Mar 17, 2022 at 11:11:21AM -0700, Nick Desaulniers wrote:
> > > > > Our goal is to enable -Wformat for CC=clang.  Please see also:
> > > > > commit cbacb5ab0aa0 ("docs: printk-formats: Stop encouraging use of
> > > > > unnecessary %h[xudi] and %hh[xudi]")
> > > >
> > > > Not that I agree on that commit for %h[h]x
> > > >
> > > >         signed char ch = -1;
> > > >         printf("%x\n", ch);
> > > >         printf("%hhx\n", ch);
> > >
> > > Will print:
> > > ffffffff
> > > ff
> > >
> > I noticed this. My first thought was to do something akin to:
> >
> >   printf("%x\n", (u8)ch);
> >
> > but went the route of removing the "h" qualifiers to be more in line
> > with previous fixes. I will be happy to change this patch if that's
> > what you would prefer.
>
> Should we add a note diagnostic to clang suggesting the explicit cast
> as one method of silencing the warning?

I don't think we should offer multiple suggestions in the notes. It
could become confusing and make the diagnostic messages much bigger.
That doesn't mean we couldn't change the suggestion. :-)

-bw