Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755804AbXFXTki (ORCPT ); Sun, 24 Jun 2007 15:40:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751433AbXFXTkb (ORCPT ); Sun, 24 Jun 2007 15:40:31 -0400 Received: from mail-in-03.arcor-online.net ([151.189.21.43]:59011 "EHLO mail-in-03.arcor-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751352AbXFXTka (ORCPT ); Sun, 24 Jun 2007 15:40:30 -0400 In-Reply-To: References: <20070624174732.GZ21478@ftp.linux.org.uk> <20070624183547.GA21478@ftp.linux.org.uk> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <1a25667a20e43a072f733a3ec2b8e79d@kernel.crashing.org> Content-Transfer-Encoding: 7bit Cc: Al Viro , linux-kernel@vger.kernel.org, linux-sparse@vger.kernel.org From: Segher Boessenkool Subject: Re: [PATCH 16/16] fix handling of integer constant expressions Date: Sun, 24 Jun 2007 21:40:06 +0200 To: Linus Torvalds X-Mailer: Apple Mail (2.623) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 844 Lines: 25 >> Why? I'd say it's not better than BUILD_BUG_ON_ZERO() use >> instead of that ?: > > Oh, _that_ part I have no problem with. It's more that it seems that > the > gcc optimization is ok at least as an extension. Sure, but it's not an extension (yet), but an implementation side-effect; it would have to be (semi-formally) defined in the manual to be an extension. Until that happens, anyone using this "feature" risks haven his code broken at any time (or, rather, his code already was broken but he didn't know it). See gcc.gnu.org/PR456 for more discussion. Yes it's an old bug... Segher - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/