linux-kernel - Re: [PATCH] regmap: silence GCC warning

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Message-ID: <20121003110646.GD4360@opensource.wolfsonmicro.com>
Date:	Wed, 3 Oct 2012 12:06:47 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Paul Bolle <pebolle@...cali.nl>
Cc:	Valdis.Kletnieks@...edu,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regmap: silence GCC warning

On Wed, Oct 03, 2012 at 09:23:36AM +0200, Paul Bolle wrote:
> On Tue, 2012-10-02 at 20:11 -0400, Valdis.Kletnieks@...edu wrote:
> > On Mon, 01 Oct 2012 11:03:21 +0100, Mark Brown said:

> > > > That implies that 'ret' will be set in the if-branch. ('val_count' could
> > > > be zero if 'val_len' is, for example, zero. That would be useless input,
> > > > however.)

> > But gcc doesn't know what "useless input" means, semantically.

> Correct. When this function is compiled gcc has to take into account
> that 'val_len' will be called with useless input, like zero.

> By the way, GCC doesn't warn if I add an early check whether 'val_count'
> is non-zero:

That's a much more useful fix, bodging things by just forcing things to
be assigned (especially with the way you were converting the immediate
returns) is generally terrible - it's just shutting up the errors
without actually fixing any issues that really exist and means that if
the compiler ever notices actual issues we won't see them.
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