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

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Date:	Thu, 28 Jul 2016 14:22:02 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Ingo Molnar <mingo@...nel.org>, Arnd Bergmann <arnd@...db.de>,
	Michal Marek <mmarek@...e.com>
Cc:	Borislav Petkov <bp@...en8.de>, Sam Ravnborg <sam@...nborg.org>,
	lkml <linux-kernel@...r.kernel.org>, Michael Matz <matz@...e.de>,
	Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
	x86-ml <x86@...nel.org>
Subject: Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1

On Thu, Jul 28, 2016 at 12:03 PM, Linus Torvalds
<torvalds@...ux-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