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Message-ID: <1154050195.44c968932df8d@portal.student.luth.se>
Date: Fri, 28 Jul 2006 03:29:55 +0200
From: ricknu-0@student.ltu.se
To: Nicholas Miell <nmiell@comcast.net>
Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com>, linux-kernel@vger.kernel.org,
       Andrew Morton <akpm@osdl.org>, Jeff Garzik <jeff@garzik.org>,
       Alexey Dobriyan <adobriyan@gmail.com>,
       Vadim Lobanov <vlobanov@speakeasy.net>,
       Jan Engelhardt <jengelh@linux01.gwdg.de>,
       Shorty Porty <getshorty_@hotmail.com>,
       Peter Williams <pwil3058@bigpond.net.au>, Michael Buesch <mb@bu3sch.de>,
       Pekka Enberg <penberg@cs.helsinki.fi>,
       Stefan Richter <stefanr@s5r6.in-berlin.de>, larsbj@gullik.net,
       Paul Jackson <pj@sgi.com>
Subject: Re: [RFC][PATCH] A generic boolean (version 6)
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Citerar Nicholas Miell <nmiell@comcast.net>:

> On Thu, 2006-07-27 at 21:55 +0200, ricknu-0@student.ltu.se wrote:
> > Citerar Nicholas Miell <nmiell@comcast.net>:
> > 
> > > If _Bool does end up in the user-kernel ABI, be advised that validating
> > > them will be tricky ("b == true || b == false" or "!!b" won't work), and
> > 
> > Why would !!b not work?
> > I don't think it should end up in the ABI (at least, not yet). Just asking
> > because I'm curious. :)
> > 
> 
> The compiler knows that "b = !!b;" is a no-op.

In what gcc version? Using 4.0.2 myself and got that if b equals 12 (using a
pointer to add the value to the boolean) then !!b equals 1.

/Richard Knutsson