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Date: Thu, 28 Jul 2016 19:56:47 +0200
From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sam Ravnborg <sam@ravnborg.org>, lkml <linux-kernel@vger.kernel.org>,
        Michael Matz <matz@suse.de>, linux-kbuild@vger.kernel.org,
        x86-ml <x86@kernel.org>
Subject: Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1
Message-ID: <20160728175647.GB316@x4>
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On 2016.07.28 at 10:46 +0200, Borislav Petkov wrote:
> On Thu, Jul 28, 2016 at 10:29:15AM +0200, Ingo Molnar wrote:
> > BUT, isn't this the natural state of things, that the 'final' warnings
> > that don't get fixed are the obnoxious, false positive ones - because
> > anyone who looks at them will say "oh crap, idiotic compiler!"?
> 
> Hmm, so my experience is like Linus' - that -Wmaybe thing generates too
> much noise and a lot of false positives. The thing is, as Micha (on CC)
> explained it to me, that warning simply says that GCC sometimes *cannot*
> know whether the variable will be used uninitialized or not and eagerly
> issues the warning message, just in case.

Another issue is that the number of warnings you get depend on the
optimization level. So -Os may be different from -O2 and once you use
-O3 (I know it is not officially supported) you will drown in false
positives...

-- 
Markus