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

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Date:	Thu, 28 Jul 2016 12:08:37 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Ingo Molnar <mingo@...nel.org>
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:
>
> Once we get to the point that the warning is no longer useful, and is
> more pain than gain, it gets disabled.

Btw, I have a suspicion that you didn't realize that
"-Wmaybe-uninitialized" is separate from "-Wuninitialized" (which is
*not* disabled).

The "maybe-uninitialized" warning is literally gcc saying "I haven't
really followed all the logic, but from my broken understanding it
isn't _obvious_ that it is initialized".

And the problem is that a lot of gcc optimization choices basically
move the pointer of "obvious". So the warning is a bit random to begin
with. And when the gcc people screw thigns up, things go to hell in a
handbasket.

             Linus