linux-kernel - Re: [PATCH] kconfig: plug false-positive warning in get_prompt

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Message-ID: <alpine.DEB.2.02.1406230228370.8821@chino.kir.corp.google.com>
Date:	Mon, 23 Jun 2014 02:29:42 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
cc:	Konstantin Khlebnikov <koct9i@...il.com>,
	"Yann E. MORIN" <yann.morin.1998@...e.fr>,
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kconfig: plug false-positive warning in get_prompt_str()
 seen with gcc-4.9

On Mon, 23 Jun 2014, Uwe Kleine-König wrote:

> > scripts/kconfig/menu.c: In function ‘get_symbol_str’:
> > scripts/kconfig/menu.c:590:18: warning: ‘jump’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> >      jump->offset = strlen(r->s);
> >                   ^
> > scripts/kconfig/menu.c:551:19: note: ‘jump’ was declared here
> >   struct jump_key *jump;
> >                    ^
> 
> I'm seeing that problem with a 4.8.2 toolchain on next-20140623 with
> ARCH=arm, too.
> 
> Maybe better use uninitialized_var? And point out the commit that
> introduced the issue please.
> 

If the compiler can't figure out if a variable is always intialized before 
its referenced, then it indicates the code is poorly written and isn't 
clear to the code reader either.  uninitialized_var() would be a lazy way 
to solve this particular issue.