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From: Paul Eggert <eggert@cs.ucla.edu>
To: Sam James <sam@gentoo.org>, Gnulib bugs <bug-gnulib@gnu.org>
Cc: "Arsen Arsenović" <arsen@aarsen.me>
Subject: Re: Making _Noreturn a no-op in < Clang 16?
Date: Wed, 18 Jan 2023 20:17:39 -0800	[thread overview]
Message-ID: <575c1ae6-d77d-9001-9f9b-a803778446c6@cs.ucla.edu> (raw)
In-Reply-To: <F3CDF510-E88C-4BDC-99E9-E10004E6ADF3@gentoo.org>

The problem we found in Gawk was that this sort of function call:

     (b ? f : g) (x)

is mishandled by Clang < 16 when one function is _Noreturn and the other 
isn't, in that Clang mistakenly treats the call as if both functions are 

I expect this sort of issue to be reasonably rare in practical C code, 
as most people don't write code like the above, and when they do then 
typically F is _Noreturn if and only if G is also _Noreturn. So I've 
held off on doing the more-drastic "#define _Noreturn /*empty*/" for 
Clang < 16 in Gnulib, as my guess has been that the advantages of 
enabling _Noreturn on Clang < 16 are greater than the disadvantages 
given the rarity of situations like the above.

Of course I could be wrong....

  reply	other threads:[~2023-01-19  4:17 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 [this message]
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
2023-01-20  9:16             ` Paul Eggert
2023-01-20 10:25               ` Bruno Haible

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