From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Triplett Subject: Re: idio{,ma}tic typos (was Re: + fix-vm_can_nonlinear-check-in-sys_remap_file_pages.patch added to -mm tree) Date: Wed, 10 Oct 2007 11:08:53 -0700 Message-ID: <470D1535.6030708@freedesktop.org> References: <20071010104540.GA6366@localhost.sw.ru> <118833cc0710100635x205503a2peb73d24384538afa@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail5.sea5.speakeasy.net ([69.17.117.7]:44648 "EHLO mail5.sea5.speakeasy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755108AbXJJSJE (ORCPT ); Wed, 10 Oct 2007 14:09:04 -0400 In-Reply-To: <118833cc0710100635x205503a2peb73d24384538afa@mail.gmail.com> Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: Morten Welinder Cc: Alexey Dobriyan , Al Viro , linux-kernel@vger.kernel.org, davej@codemonkey.org.uk, Pierre Ossman , akpm@osdl.org, linux-sparse@vger.kernel.org Morten Welinder wrote: >> While we're at it, below is somewhat ugly sparse patch for detecting >> "&& 0x" typos. > > Excellent idea, and there is something to be said about a low-footprint patch > like that. However, if you really want to capture this kind of bugs, you would > need to have some kind "not a boolean" or "bitfield" attribute that > can propagate. > For example, you would want > > if (foo && (BAR | BAZ)) ...; > > with BAR and BAZ being hex constants to produce the same warning. > > Incidentally, it is probably not just hex constants that deserve this treatment: > octal constants and variations of (1 << cst) are of the same nature. As well > as enums defined in such manners. Sparse has a notion of "integer constant expression" already, which it uses to validate expressions used for things like bitfield widths or array sizes. I could easily have Sparse warn on any use of an integer constant expression as an operand of || or &&. However, I can imagine that that might lead to some false positives when intentionally using an integer constant expression in a condition and expecting the compiler to optimize it out at compile time. - Josh Triplett