From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7EE0CC433FF for ; Wed, 31 Jul 2019 06:38:03 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 52B53206A2 for ; Wed, 31 Jul 2019 06:38:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 52B53206A2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38338 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsiFO-0002ev-LU for qemu-devel@archiver.kernel.org; Wed, 31 Jul 2019 02:38:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35036) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hsiEw-0002BY-8I for qemu-devel@nongnu.org; Wed, 31 Jul 2019 02:37:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hsiEu-0003OL-7p for qemu-devel@nongnu.org; Wed, 31 Jul 2019 02:37:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45876) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hsiEu-00035h-1r for qemu-devel@nongnu.org; Wed, 31 Jul 2019 02:37:32 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D43783083391; Wed, 31 Jul 2019 06:37:27 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-116-51.ams2.redhat.com [10.36.116.51]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 89EAE5D6A7; Wed, 31 Jul 2019 06:37:27 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 09C0B1138619; Wed, 31 Jul 2019 08:37:26 +0200 (CEST) From: Markus Armbruster To: Paolo Bonzini References: <20190726120542.9894-1-armbru@redhat.com> <20190726120542.9894-24-armbru@redhat.com> <20190729194414.GG4313@habkost.net> <87d0hreqh3.fsf_-_@dusky.pond.sub.org> <8bea0201-f796-d682-22e6-069985b45523@redhat.com> <0eb2518f-147c-2b47-f48c-3af26bf5d264@redhat.com> Date: Wed, 31 Jul 2019 08:37:26 +0200 In-Reply-To: <0eb2518f-147c-2b47-f48c-3af26bf5d264@redhat.com> (Paolo Bonzini's message of "Tue, 30 Jul 2019 15:28:57 +0200") Message-ID: <87zhku90bd.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Wed, 31 Jul 2019 06:37:27 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] When to use qemu/typedefs.h X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Richard Henderson , Eduardo Habkost , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Paolo Bonzini writes: > On 30/07/19 15:15, Eric Blake wrote: >>> We occasionally give up and use types directly rather than their typedef >>> names, flouting the coding style. This patch does. Trades messing with >>> qemu/typedefs.h for having to write 'struct' a few times. > > I think Markus made the right call here. Using "struct Foo;" in headers > is a null price to pay if all you need is declaring a pointer-typed > field or parameter. Eduardo posted a patch to HACKING to clarify this non-usage of typedef is okay. Should we continue to mandate typedef names elsewhere? It adds cognitive load: you have to decide where to put the typedef, and when not to use it. > Of course this doesn't apply if you have to embed a > struct directly, but then qemu/typedefs.h wouldn't help either. Yes, and if this leads to an inclusion cycle, I strongly suspect "fat" headers: since you can't embed something in itself, the cycle must involve different things, all bunched together in the same header. > In general unless you're adding a new subsystem, qemu/typedefs.h should > only decrease in size, never increase. This series grows it some. I'll try to avoid that for v2. > (And there are certainly many > cases where typedefs.h are not needed, but cleaning that up is > understandably not high on the todo list). On the other hand, low-hanging fruit.