linux-kernel - Re: [PATCH] ASoC: rt1011: Mark format integer literals as unsigned

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Date:   Thu, 6 Jun 2019 13:09:19 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Shuming Fan <shumingf@...ltek.com>,
        Mark Brown <broonie@...nel.org>,
        Bard Liao <bardliao@...ltek.com>,
        Oder Chiou <oder_chiou@...ltek.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        alsa-devel@...a-project.org, LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] ASoC: rt1011: Mark format integer literals as unsigned

On Thu, Jun 06, 2019 at 11:50:10AM -0700, Nick Desaulniers wrote:
> On Wed, Jun 5, 2019 at 10:13 PM Nathan Chancellor
> <natechancellor@...il.com> wrote:
> >
> > Clang warns:
> >
> > sound/soc/codecs/rt1011.c:1291:12: warning: integer literal is too large
> > to be represented in type 'long', interpreting as 'unsigned long' per
> > C89; this literal will have type 'long long' in C99 onwards
> > [-Wc99-compat]
> >                 format = 2147483648; /* 2^24 * 128 */
> 
> This number's bitpattern is a leading one followed by 31 zeros.
> `format` is declared as `unsigned int`, and literals in C are signed
> unless suffixed, so this patch LGTM.  Maybe a macro declaring such a
> bitpattern would improve readability over the existing magic constant
> and comment?

I thought about it but that is ultimately up to the maintainer I think.

> Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
> 
> >                          ^
> > sound/soc/codecs/rt1011.c:2123:13: warning: integer literal is too large
> > to be represented in type 'long', interpreting as 'unsigned long' per
> > C89; this literal will have type 'long long' in C99 onwards
> > [-Wc99-compat]
> >                         format = 2147483648; /* 2^24 * 128 */
> >                                  ^
> > 2 warnings generated.
> >
> > Mark the integer literals as unsigned explicitly so that if the kernel
> > does ever bump the C standard it uses, the behavior is consitent.
> 
> s/consitent/consistent/
> 
> :set spell

Grr... I can send a v2 unless the maintainer wants to manually fix it
up. Thank you for the review as always.

Nathan