linux-kernel - Re: [PATCH]kconfig/menu.c: fix uninitialized variable warning

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Date:	Fri, 20 Sep 2013 21:02:17 +0200
From:	"Yann E. MORIN" <yann.morin.1998@...e.fr>
To:	Benjamin Poirier <bpoirier@...e.de>
Cc:	Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>, mmarek@...e.cz,
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH]kconfig/menu.c: fix uninitialized variable warning

Benjamin, Madhavan, All,

On 2013-09-20 13:58 -0400, Benjamin Poirier spake thusly:
> On 2013/09/20 08:05, Madhavan Srinivasan wrote:
> > On Friday 20 September 2013 01:34 AM, Yann E. MORIN wrote:
> > > Benjamin, All,
> > > 
> > > On 2013-09-19 15:13 -0400, Benjamin Poirier spake thusly:
> > >> On 2013/09/19 19:27, Yann E. MORIN wrote:
> > >>> Benjamin, Madhavan, All,
> > >>>
> > >>> On 2013-09-19 11:22 -0400, Benjamin Poirier spake thusly:
> > >>>> On 2013/09/19 12:58, Madhavan Srinivasan wrote:
> > >>>>> In file included from scripts/kconfig/zconf.tab.c:2537:0:
> > >>>>> scripts/kconfig/menu.c: In function ‘get_symbol_str’:
> > >>>>> scripts/kconfig/menu.c:586:18: warning: ‘jump’ may be used uninitialized in
> > >>>>> this function [-Wmaybe-uninitialized]
> [...]
> > >>>>
> > >>>> I do not see this warning with gcc 4.7.2 or 4.8.1. Which version are you
> > >>>> using?
> > >>>>
> [...]
> > > 
> > > No, I was not able to reproduce it with either gcc-4.4.7, gcc-4.6.4 or
> > > gcc-4.7.3 on my Ubuntu 13.04. Neither gcc-4.5 nor 4.8 are packaged, so
> > > I could not test them.
> > > 
> > > Anyway, -Wmaybe-uninitialized is new with 4.7. So, the warning can't
> > > happen with gcc < 4.7.
> > > 
> > > Madhavan, what gcc version are you using?
> > gcc i have is gcc version 4.8.0 20130526
> 
> In that case, I don't have a strong opinion whether the patch should be
> merged or not, but if it is merged, I think a comment should be added to
> the code or the changelog stating that this is to work around a
> deficiency observed in gcc 4.8.0.

If it is /fixed/ in gcc 4.8.1 (as you imply since you tested it), I
don't see a reason to apply this patch, in the end.

Rather, I would just put a comment in the code stating this is a
spurious warning, and keep the code as-is.

Madhavan, care to resend your patch with such a comment instead of
setting jump=NULL, please?

Regards,
Yann E. MORIN.

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