From: Andreas Schwab <schwab@suse.de>
To: Vincent Sweeney <v.sweeney@dexterus.com>
Cc: vda <vda@port.imtp.ilyichevsk.odessa.ua>, linux-kernel@vger.kernel.org
Subject: Re: [BUG] Bad #define, nonportable C, missing {}
Date: 21 Nov 2001 15:25:02 +0100 [thread overview]
Message-ID: <jeu1vo9p6p.fsf@sykes.suse.de> (raw)
In-Reply-To: <01112112401703.01961@nemo> <3BFB9FAE.DB9B6003@dexterus.com>
In-Reply-To: <3BFB9FAE.DB9B6003@dexterus.com> (Vincent Sweeney's message of "Wed, 21 Nov 2001 12:35:58 +0000")
Vincent Sweeney <v.sweeney@dexterus.com> writes:
|> vda wrote:
|> > ------------------------------------------------------------------
|> > Undefined behavior by C std: inc/dec may happen before dereference.
|> > Probably GCC is doing inc after right side eval, but standards say nothing
|> > about it AFAIK. Move ++ out of the statement to be safe:
|> > *a++ = byte_rev[*a]; => *a = byte_rev[*a]; a++;
|>
|> C std says *always* evaluate from right to left for = operators, so this
|> will always make perfect sense.
No. It is undefined which of the operator's arguments is evaluated first,
unless it is defined otherwise (only for ||, && and comma).
Andreas.
--
Andreas Schwab "And now for something
Andreas.Schwab@suse.de completely different."
SuSE Labs, SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
next prev parent reply other threads:[~2001-11-21 14:25 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-11-21 12:40 [BUG] Bad #define, nonportable C, missing {} vda
2001-11-21 11:10 ` Andreas Schwab
2001-11-21 11:16 ` Tim Waugh
2001-11-21 12:31 ` Ragnar Hojland Espinosa
2001-11-21 13:40 ` Jan Hudec
2001-11-21 14:19 ` Andreas Schwab
2001-11-21 14:52 ` Alexander Viro
2001-11-21 18:23 ` Neil Booth
2001-11-21 12:35 ` Vincent Sweeney
2001-11-21 13:37 ` Jan Hudec
2001-11-21 13:52 ` Mathijs Mohlmann
2001-11-21 17:12 ` vda
2001-11-26 20:28 ` Alan Cox
2001-11-27 18:03 ` vda
2001-11-27 18:38 ` Andreas Dilger
2001-11-28 13:19 ` vda
2001-11-21 14:12 ` Richard B. Johnson
2001-11-21 14:33 ` Eric W. Biederman
2001-11-21 14:56 ` Alexander Viro
2001-11-21 14:59 ` Andreas Schwab
2001-11-21 15:48 ` Momchil Velikov
2001-11-21 16:52 ` vda
2001-11-21 14:24 ` Sean Hunter
2001-11-21 14:25 ` Andreas Schwab [this message]
2001-11-22 20:43 ` Chris Gray
2001-11-22 4:24 ` Stevie O
2001-11-22 11:46 ` Horst von Brand
2001-11-22 12:03 ` Alexander Viro
2001-11-22 20:08 ` J.A. Magallon
[not found] ` <01112311540300.00886@manta>
2001-11-23 14:43 ` J.A. Magallon
-- strict thread matches above, loose matches on Subject: below --
2001-11-27 19:03 Nathan Myers
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