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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: Thu, 19 Jan 2023 21:30:05 +0000	[thread overview]
Message-ID: <ED095B6B-D147-4707-B95D-A193742774B0@gentoo.org> (raw)
In-Reply-To: <1e4c77c2-5d65-0e73-84b8-37d888053a26@cs.ucla.edu>

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> On 19 Jan 2023, at 21:20, Paul Eggert <eggert@cs.ucla.edu> wrote:
> On 1/19/23 12:44, Sam James wrote:
>> _Noreturn is pretty much just an optimisation (and I'm not convinced that it's _needed_  in a lot of cases, rather just a useful hint).
> _Noreturn is not just an optimization: it's also useful for static checking. For example:
>  int
>  f (int x)
>  {
>     if (x < INT_MAX)
>       return x + 1;
>     error (1, 0, "x is too large");
>  }
> Since error is _Noreturn the compiler knows not to warn that F might return garbage. It's useful to suppress false alarms, even when Clang is the compiler.

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.

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  reply	other threads:[~2023-01-19 21:31 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 [this message]
2023-01-20  3:40         ` Paul Eggert
2023-01-20  4:20           ` Sam James
2023-01-20  9:16             ` Paul Eggert
2023-01-20 10:25               ` Bruno Haible

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