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From: Nix <nix@esperi.org.uk>
To: Duncan Sands <duncan.sands@math.u-psud.fr>
Cc: linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@osdl.org>,
	Mitchell Blank Jr <mitch@sfgoth.com>,
	Jan Engelhardt <jengelh@linux01.gwdg.de>
Subject: Re: sparse segfaults
Date: Tue, 23 Nov 2004 13:59:19 +0000	[thread overview]
Message-ID: <87y8gswts8.fsf@amaterasu.srvr.nix> (raw)
In-Reply-To: <200411222130.46247.duncan.sands@math.u-psud.fr> (Duncan Sands's message of "22 Nov 2004 20:53:34 -0000")

On 22 Nov 2004, Duncan Sands mused:
> Generalized lvalues have been removed.  Check out
> http://gcc.gnu.org/ml/gcc/2004-11/msg00604.html

There is talk of putting a subset of them back again, because a *lot* of
code does things like

((foo_t *)foo)++;

and the generalized lvalues extension makes that work as expected. Yes,
all such code is technically broken, but a large number of non-GCC
compilers also implement the extension enough for the construct above to
be valid.


Where it's really bad is in C++, where it can change the semantics of
some otherwise-valid code (due to the way it interacts with function
overloading). The whole generalized lvalues extension is definitely not
coming back, because fixing that C++ bug was a major reason why it was
removed in the first place.

-- 
`The sword we forged has turned upon us
 Only now, at the end of all things do we see
 The lamp-bearer dies; only the lamp burns on.'

  reply	other threads:[~2004-11-23 13:59 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-11-20 14:37 sparse segfaults Russell King
2004-11-20 16:58 ` Linus Torvalds
2004-11-20 17:23   ` Russell King
2004-11-21 22:10 ` linux-os
2004-11-21 22:29   ` Nikita Danilov
2004-11-21 22:37   ` Linus Torvalds
2004-11-21 22:44     ` Jan Engelhardt
2004-11-21 23:43       ` Mitchell Blank Jr
2004-11-22  1:02       ` Linus Torvalds
2004-11-22 10:33         ` Jan Engelhardt
2004-11-22 16:22           ` Linus Torvalds
2004-11-22 18:21             ` Jan Engelhardt
2004-11-22 18:39             ` Mitchell Blank Jr
2004-11-22 18:54               ` Linus Torvalds
2004-11-22 20:30                 ` Duncan Sands
2004-11-23 13:59                   ` Nix [this message]
2004-11-22 19:16               ` Linus Torvalds
  -- strict thread matches above, loose matches on Subject: below --
2005-03-26 22:48 Jan Engelhardt

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