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From: Paul Eggert <eggert@cs.ucla.edu>
To: Sam James <sam@gentoo.org>
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 13:20:38 -0800	[thread overview]
Message-ID: <1e4c77c2-5d65-0e73-84b8-37d888053a26@cs.ucla.edu> (raw)
In-Reply-To: <B9404A70-AD4B-4F33-943D-8EEE7843AC2B@gentoo.org>

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:

   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.

 > Is there any precedent wrt
 > handling miscompilations for actively supported compilers in gnulib 
and such?

We've run into them before; I don't know of a list of instances. 
Generally speaking if the workaround is easy and harmless we can install 
it, otherwise we tell users to get a working compiler.

  reply	other threads:[~2023-01-19 21:21 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 [this message]
2023-01-19 21:30       ` Sam James
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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