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From: Sam James <sam@gentoo.org>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: "Gnulib bugs" <bug-gnulib@gnu.org>, "Arsen Arsenović" <arsen@aarsen.me>
Subject: Re: Making _Noreturn a no-op in < Clang 16?
Date: Fri, 20 Jan 2023 04:20:09 +0000	[thread overview]
Message-ID: <A8369EFC-0DE0-4EB0-BD19-359FB3791650@gentoo.org> (raw)
In-Reply-To: <540715fe-d55f-ab64-0d0e-9942ab04fbc1@cs.ucla.edu>

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> On 20 Jan 2023, at 03:40, Paul Eggert <eggert@cs.ucla.edu> wrote:
> On 1/19/23 13:30, Sam James wrote:
>> Right, I just meant that we don't tend to care about quieting warnings with older compilers,
>> and it's not useful from a static analysis perspective here either given that older Clangs can't be trusted.
>> It is of course useful as an attribute in general. I don't think either of these things are really
>> a downside to committing the workaround here. If we get folks who get build failures with extra warnings
>> enabled, we can tell them to upgrade their compiler.
> But clang 16 isn't out yet, so we can't reasonably tell people to upgrade.
> And even if it clang 16 were out, I can't reasonably tell all Emacs developers to switch to it right away. Many of them are using Apple's compiler and will upgrade whenever. Plain './configure; make' on a bleeding-edge Emacs built from Git with Clang 15 would generate 270 false alarms if we simply did "#define _Noreturn /**/", and I expect many Emacs developers would be annoyed by that (or would stop paying attention to any correct diagnostics mixed in with the flood of false positives).

I take your point and it's fair enough. Thanks for hashing it out with me.

> With that in mind, how about the attached Gnulib patch? (I haven't installed it.) The basic idea is to "#define _Noreturn /**/" on buggy clangs if a cautious builder compiles with -D_GL_WORK_AROUND_LLVM_BUG_5979.<0001-snippet-_Noreturn-work-around-Clang-_Noreturn-bug.patch>

If it's not too much of a hassle, this works for me, because at least we advertise the problem a bit, and we can tell distros
to set -D_... if they're stuck on older Clang for a bit.

Cheers Paul.


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  reply	other threads:[~2023-01-20  4:21 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-19  2:09 Making _Noreturn a no-op in < Clang 16? Sam James
2023-01-19  4:17 ` Paul Eggert
2023-01-19 20:44   ` Sam James
2023-01-19 21:20     ` Paul Eggert
2023-01-19 21:30       ` Sam James
2023-01-20  3:40         ` Paul Eggert
2023-01-20  4:20           ` Sam James [this message]
2023-01-20  9:16             ` Paul Eggert
2023-01-20 10:25               ` Bruno Haible

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