Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1

From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Michal Marek <mmarek@suse.com>
Cc: Borislav Petkov <bp@alien8.de>, Sam Ravnborg <sam@ravnborg.org>,
	lkml <linux-kernel@vger.kernel.org>, Michael Matz <matz@suse.de>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	x86-ml <x86@kernel.org>
Subject: Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1
Date: Thu, 28 Jul 2016 14:22:02 -0700	[thread overview]
Message-ID: <CA+55aFxT4Wvg_yeKbiksoe5btDW59oW1SHK=JaBAJ-L3YGWxQQ@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFznBSQC+_KFq39eT2yTOd_cidqQ5viBLG6mshb_U_Y2EA@mail.gmail.com>

On Thu, Jul 28, 2016 at 12:03 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> And the new warnings were actually not so much due to new code in 4.7,
> as the fact that in between I did a user-space upgrade, and gcc 6.1.1
> has regressed to the point of the warnings being an unusable mess.

Actually, thinking more about this, I'm not convinced it's a gcc
regression, because older gcc's have defainitely had the same problem
with that warning causing tons of spurious issues.

So it might actually mostly be due commit 877417e6ffb9 ("Kbuild:
change CC_OPTIMIZE_FOR_SIZE definition"). As a result of that, we now
end up not using CC_OPTIMIZE_FOR_SIZE for allmodconfig builds.

And since for us, -Os always disabled that warning anyway (because gcc
has always made a bad job of it), the bogus warnings didn't use to be
so annoying and hide the real things.

Of course, a big part of the reasoning for that commit was apparently
because Arnd liked the warning. It back-fired. Now that warning is
gone for everybody, because it's so broken.

                   Linus