Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753123AbaAGGDp (ORCPT ); Tue, 7 Jan 2014 01:03:45 -0500 Received: from asavdk4.altibox.net ([109.247.116.15]:52577 "EHLO asavdk4.altibox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751514AbaAGGDn (ORCPT ); Tue, 7 Jan 2014 01:03:43 -0500 X-Greylist: delayed 471 seconds by postgrey-1.27 at vger.kernel.org; Tue, 07 Jan 2014 01:03:43 EST Date: Tue, 7 Jan 2014 06:55:32 +0100 From: Sam Ravnborg To: Josh Triplett Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Greg Kroah-Hartman , Michal Marek , Rashika Kheria Subject: Re: #pragma once? Message-ID: <20140107055532.GA16581@ravnborg.org> References: <20140106204706.GA16924@leaf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140106204706.GA16924@leaf> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 06, 2014 at 12:47:07PM -0800, Josh Triplett wrote: > [CCing build-system folks and others likely to know about potential > issues.] > > Does anyone have any objection to the use of "#pragma once" instead of > the usual #ifndef-#define-...-#endif include guard? GCC, LLVM/clang, > and the latest Sparse all support either method just fine. (I added > support to Sparse myself.) Both have equivalent performance. "#pragma > once" is simpler, and avoids the possibility of a typo in the defined > guard symbol. For kernel headers no concern. For UAPI headers we should be more carefull - as we do not know which compiler it ends up seeing - and what version. Sam -- 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/