linux-kernel - Re: [PATCH 0/2] kbuild: remove gcc's -Wtype-limits

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Message-ID: <20251218202644.0bd24aa8@pumpkin>
Date: Thu, 18 Dec 2025 20:26:44 +0000
From: David Laight <david.laight.linux@...il.com>
To: Vincent Mailhol <mailhol@...nel.org>
Cc: Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nsc@...nel.org>,
 Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling
 <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>, Maarten
 Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
 <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
 <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Chris Mason
 <clm@...com>, David Sterba <dsterba@...e.com>, Linus Torvalds
 <torvalds@...ux-foundation.org>, linux-kbuild@...r.kernel.org,
 linux-sparse@...r.kernel.org, linux-kernel@...r.kernel.org,
 llvm@...ts.linux.dev, dri-devel@...ts.freedesktop.org,
 linux-btrfs@...r.kernel.org
Subject: Re: [PATCH 0/2] kbuild: remove gcc's -Wtype-limits

On Thu, 18 Dec 2025 19:50:00 +0100
Vincent Mailhol <mailhol@...nel.org> wrote:

> I often read on the mailing list people saying "who cares about W=2
> builds anyway?". At least I do. Not that I want to fix all of them,
> but on some occasions, such as new driver submissions, I have often
> found a couple valid diagnostics in the W=2 output.
> 
> That said, the annoying thing is that W=2 is heavily polluted by one
> warning: -Wtype-limits. Try a gcc W=2 build on any file and see the
> results for yourself. I suspect this to be the reason why so few
> people are using W=2.

One possibility is to conditionally add _Pragma() inside #defines to
turn off the warning for the main false positives (I guess all the
BUILD_BUG_xxxx and statically_true are the main ones).
But don't 'bloat' the #define expansions for normal builds.

	David