linux-kernel - Re: Conversion to generic boolean

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Message-ID: <Pine.LNX.4.61.0608291416370.8031@yvahk01.tjqt.qr>
Date:	Tue, 29 Aug 2006 14:17:12 +0200 (MEST)
From:	Jan Engelhardt <jengelh@...ux01.gwdg.de>
To:	Christoph Hellwig <hch@...radead.org>
cc:	Nicholas Miell <nmiell@...cast.net>,
	Richard Knutsson <ricknu-0@...dent.ltu.se>,
	James.Bottomley@...elEye.com, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Conversion to generic boolean

>> > 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.

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


Jan Engelhardt
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