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From: Peter Williams <pwil3058@bigpond.net.au>
To: Jan Engelhardt <jengelh@linux01.gwdg.de>
Cc: Christoph Hellwig <hch@infradead.org>,
	Nicholas Miell <nmiell@comcast.net>,
	Richard Knutsson <ricknu-0@student.ltu.se>,
	James.Bottomley@SteelEye.com, linux-scsi@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: Conversion to generic boolean
Date: Tue, 29 Aug 2006 23:26:10 +1000	[thread overview]
Message-ID: <44F44072.4020506@bigpond.net.au> (raw)
In-Reply-To: <Pine.LNX.4.61.0608291416370.8031@yvahk01.tjqt.qr>

Jan Engelhardt wrote:
>>>> That is error-prone. Not "==FALSE" but what happens if x is (for some 
>>>> reason) not 1 and then "if (x==TRUE)".
>>> If you're using _Bool, that isn't possible. (Except at the boundaries
>>> where you have to validate untrusted data -- and the compiler makes that
>>> more difficult, because it "knows" that a _Bool can only be 0 or 1 and
>>> therefore your check to see if it's not 0 or 1 can "safely" be
>>> eliminated.)
>> gcc lets you happily assign any integer value to bool/_Bool, so unless
> 
> But, it coerces the rvalue into 0 or 1, which may be a gain.

Actually, it's not coercion.  It's the result of evaluating the value as 
a boolean expression.

> 
>> you write sparse support for actually checking things there's not the
>> slightest advantage in value range checking.
> 
> 
> Jan Engelhardt


-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce

  reply	other threads:[~2006-08-29 13:26 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-26  3:24 Conversion to generic boolean Richard Knutsson
2006-08-28  9:32 ` Christoph Hellwig
2006-08-28  9:45   ` Jesper Juhl
2006-08-29 11:39     ` Christoph Hellwig
2006-08-28 10:58   ` Jan Engelhardt
2006-08-28 11:11     ` Bernd Petrovitsch
2006-08-28 12:17     ` Richard Knutsson
2006-08-28 19:15       ` Nicholas Miell
2006-08-28 20:55         ` Richard Knutsson
2006-08-28 21:19           ` Nicholas Miell
2006-08-28 21:55             ` Richard Knutsson
2006-08-29 11:41         ` Christoph Hellwig
2006-08-29 12:17           ` Jan Engelhardt
2006-08-29 13:26             ` Peter Williams [this message]
2006-08-29 13:56               ` Jan Engelhardt
2006-08-29 12:48           ` Alan Cox
2006-08-29  0:18   ` Andrew Morton
2006-08-29  1:15     ` Nick Piggin
2006-08-29  5:58       ` Jan Engelhardt
2006-08-31  3:50         ` Dmitry Torokhov
2006-09-03 12:51           ` Pavel Machek
2006-08-29  7:29       ` Anton Altaparmakov
2006-08-29 11:46         ` Christoph Hellwig
2006-08-29 12:18           ` Anton Altaparmakov
2006-08-29 11:45     ` Christoph Hellwig
2006-08-29 14:10       ` Richard Knutsson
2006-08-29 15:47       ` Andrew Morton
  -- strict thread matches above, loose matches on Subject: below --
2006-08-29  5:43 linux

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