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

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Message-ID: <CAKwvOdkEjrPUL4HuO3UKaUZAzVw=XV1bEOSj6HR5R1WTUSSZ4w@mail.gmail.com>
Date:   Fri, 18 Mar 2022 11:01:13 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Bill Wendling <morbo@...gle.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,
        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 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

Maybe we should reconsider our recommendations for signed types?

It's probably worth adding `signed char` explicitly to
Documentation/core-api/printk-formats.rst, as it is a distinct type
from `char` in C.
-- 
Thanks,
~Nick Desaulniers