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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next prev parent 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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