linux-kernel - Re: [PATCH v3 04/57] kbuild: Drop -Wdeclaration-after-statement

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Date:   Wed, 14 Jun 2023 10:25:39 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Masahiro Yamada <masahiroy@...nel.org>
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Subject: Re: [PATCH v3 04/57] kbuild: Drop -Wdeclaration-after-statement

On Wed, Jun 14, 2023 at 03:13:03PM +0900, Masahiro Yamada wrote:
> On Mon, Jun 12, 2023 at 6:39 PM Peter Zijlstra <peterz@...radead.org> wrote:
> >
> > With the advent on scope-based resource management it comes really
> > tedious to abide by the contraints of -Wdeclaration-after-statement.
> 
> Where is the context of Linus' suggested-by?
> 
> I do not know where this came from.
> I suddenly got a huge v3 in my mailbox.
> 
> 
> I see an equivalent patch submitted last year:
> https://lore.kernel.org/lkml/Y1w031iI6Ld29IVT@p183/
> 
> Linus rejected it. Did he change his mind?

https://lkml.kernel.org/r/CAHk-%3Dwi-RyoUhbChiVaJZoZXheAwnJ7OO%3DGxe85BkPAd93TwDA%40mail.gmail.com

I'll add it as a Link tag to the Changelog.

> 
> > It will still be recommeneded to place declarations at the start of a
> > scope where possible, but it will no longer be enforced.
> 
> If you remove the warning, we will not be able to
> detect code that opts out the recommendation
> for no good reason.

Yeah, so per that thread linked above I tried to play clever games with
_Pragma() to get around this, but GCC hates on it (works fine with Clang
though).

Linus said to just give up and scrap the whole
-Wdeclaration-after-statement thing.

I suppose it'll be up to reviewers and perhaps checkpatch like things to
'enforce' the rules.