linux-kernel - Re: [PATCH 6/9] drivers/net/wireless/iwlwifi/iwl-4965.c: Correct use of ! and &

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Message-ID: <20080305081904.GA17789@elte.hu>
Date:	Wed, 5 Mar 2008 09:19:05 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Harvey Harrison <harvey.harrison@...il.com>
Cc:	Christopher Li <sparse@...isli.org>, Julia Lawall <julia@...u.dk>,
	yi.zhu@...el.com, linux-wireless@...r.kernel.org,
	ipw3945-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Alexander Viro <viro@....linux.org.uk>,
	linux-sparse@...r.kernel.org, Josh Triplett <josh@...edesktop.org>
Subject: Re: [PATCH 6/9] drivers/net/wireless/iwlwifi/iwl-4965.c: Correct
	use of ! and &


* Harvey Harrison <harvey.harrison@...il.com> wrote:

> > Al's patch is:
> > 
> > +                       if (op == '&' && expr->left->type == EXPR_PREOP &&
> > +                           expr->left->op == '!')
> > +                               warning(expr->pos, "dubious: !x & y");
> > 
> > i think there might be similar patterns: "x & !y", "!x | y", "x | !y" ?
> > 
> 
> Well, (!x & y) and (!x | y) are probably the two that might have been 
> intended otherwise.  (x & !y), (x | !y) are probably ok.

i think the proper intention in the latter cases is (x & ~y) and
(x | ~y).

My strong bet is that in 99% of the cases they are real bugs and && or 
|| was intended.

	Ingo
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