Message-ID: <3C52CFE3.2080107@ntplx.net>
Date: Sat, 26 Jan 2002 10:48:51 -0500
From: Ben Bridgwater <bennyb@ntplx.net>
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To: lkml <linux-kernel@vger.kernel.org>
Subject: Re: RFC: booleans and the kernel
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Rick Stevens wrote:

 > Granted.  "if (x)" is true if "x" is non-zero, regardless of type and
 > shoudn't even generate a warning if "x" is scalar.

Surely the major point of using the compiler's _Bool would be for type 
safety -  if you only want readability then you may as well just use:

enum bool {true = 1, false = 0};

Now since C has historically utilized integer expressions for 
conditionals (with 0, !0 truth semantics), so it would be obnoxious to 
*unconditionally* make if (x) where x is non _Bool generate warnings, 
but IMO the whole point of using _Bool would be to then choose to turn 
on warnings for non _Bool conditionals, and to suppress warnings one 
would then need to be explicit about intentions by writing code such as:

if ((_Bool) (x = y)) ;

and hopefully if one accidently wrote:

if ((_Bool) x = y) ; /* int x, y */

then the compiler would warn that you probably didn't really mean that, 
since it means:

if ((_Bool) (x = (int) (_Bool) y)) ;

Which would have converted your y to _Bool (0/1) before assigning it to x.

Ben

P.S. I'm not on the list - please CC any response to me if you want a reply.

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