From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36159) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fIx10-0001ow-VZ for qemu-devel@nongnu.org; Wed, 16 May 2018 10:02:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fIx0w-0007pV-Cd for qemu-devel@nongnu.org; Wed, 16 May 2018 10:02:51 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:51310 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fIx0w-0007pI-7y for qemu-devel@nongnu.org; Wed, 16 May 2018 10:02:46 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A031E40201A3 for ; Wed, 16 May 2018 14:02:45 +0000 (UTC) References: <20180515091356.24106-1-peterx@redhat.com> <584bbd99-11dd-8da9-a5b4-de285cebc84d@redhat.com> <20180516030750.GC9089@xz-mi> From: Eric Blake Message-ID: Date: Wed, 16 May 2018 09:02:42 -0500 MIME-Version: 1.0 In-Reply-To: <20180516030750.GC9089@xz-mi> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH RFC] qemu-error: introduce error_report_once List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: qemu-devel@nongnu.org, Markus Armbruster On 05/15/2018 10:07 PM, Peter Xu wrote: >>> + static bool __print_once; \ >> >> Double-underscore names are reserved for the compiler's use, not ours. >> Better would be naming this: >> >> static bool print_once_; >> >> with a trailing underscore, or at most a single leading underscore. >> >>> + bool __ret_print_once = !__print_once; \ >> >> Same comment for this variable. > > Sure! > > (I am wondering why Linux is always using that way to name lots of > variables, and I'm surprised that I got 385350 after I run this under > the Linux repo: 'git grep "__[a-z][a-z]" | wc -l', even considering > some false positives) git grep "\b_[_A-Z]" might be a more precise grep for use of reserved identifiers. The Linux kernel can get away with some uses that qemu does not, because it is a monolithic low-level project that is closely tied to rather specific compiler behaviors and does not have to port to other systems; rather than a user-space application that aims to be portable to multiple operating systems, compilers, and libc implementations. Also, grepping for leading double-underscore will have hits even in qemu, where we ARE taking advantage of a compiler feature (an obvious example: anywhere we #define a macro wrapper around an __attribute__ tag - __attribute__ belongs to the namespace reserved for the compiler, so it makes sense that turning on that compiler feature requires using the compiler's namespace). Or put another way, grepping for the use of reserved identifiers is easy, but grepping for where we are inappropriately declaring something that may collide (rather than using something that already exists) is a bit harder. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org