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
next prev parent reply other threads:[~2006-08-29 13:26 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <44EFBEFA.2010707@student.ltu.se>
2006-08-28 9:32 ` Conversion to generic boolean 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
2006-08-29 5:43 linux
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