linux-kernel - Re: [PATCH v4 0/2] kbuild: remove gcc's -Wtype-limits

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Message-ID: <54fe30d3-856e-45d4-ba30-b9e770d9afc6@kernel.org>
Date: Mon, 5 Jan 2026 21:47:02 +0100
From: Vincent Mailhol <mailhol@...nel.org>
To: Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nsc@...nel.org>
Cc: 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>,
 Kees Cook <kees@...nel.org>, "Gustavo A. R. Silva" <gustavoars@...nel.org>,
 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,
 linux-hardening@...r.kernel.org, Daniel Plakosh <dplakosh@....cmu.edu>
Subject: Re: [PATCH v4 0/2] kbuild: remove gcc's -Wtype-limits

On 05/01/2026 at 13:24, Nicolas Schier wrote:
> On Thu, Jan 01, 2026 at 04:21:38PM +0100, Vincent Mailhol 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.
>>
>> This series removes gcc's -Wtype-limits in an attempt to make W=2 more
>> useful. Those who do not use W=2 can continue to not use it if they
>> want. Those who, like me, use it for time to time will get an improved
>> experience from the reduced spam.
>>
>> Patch #1 deactivates -Wtype-limits. Extra details on statistics, past
>> attempts and alternatives are given in the description.
>>
>> Patch #2 clean-ups the local Kbuild -Wno-type-limits exceptions.
>>
>> Signed-off-by: Vincent Mailhol <mailhol@...nel.org>
>> ---
>> Changes in v4:
>>
>>   - Remove patch #3.
>>   - Aside from minor changes in the patch descriptions, this is
>>     basially a revert to v1.
>>
>> Link to v3: https://lore.kernel.org/r/20251220-remove_wtype-limits-v3-0-24b170af700e@kernel.org
> 
> just to prevent confusions:  As Dan silenced the Smatch warning caused
> by patch #3 [1] (thanks!), the additional comment patch [2] is obsolete
> and v3 of the series is a more complete version than v4.

Exactly!

Thanks to Daniel's effort we finally have a complete fix.

Let me know if you need any actions from my side. Otherwise, I will
assume that my part of the work is done here and will just wait for the
v3 to be picked.

(I am so happy to start 2026 by getting rid of this annoying
-Wtype-limits spam :D)

Yours sincerely,
Vincent Mailhol