From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:34285)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <peter.maydell@linaro.org>) id 1XCqtv-0003TZ-KG
	for qemu-devel@nongnu.org; Thu, 31 Jul 2014 10:00:18 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <peter.maydell@linaro.org>) id 1XCqtq-00017G-Ql
	for qemu-devel@nongnu.org; Thu, 31 Jul 2014 10:00:11 -0400
Received: from mail-la0-f53.google.com ([209.85.215.53]:63693)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <peter.maydell@linaro.org>) id 1XCqtq-000153-Jn
	for qemu-devel@nongnu.org; Thu, 31 Jul 2014 10:00:06 -0400
Received: by mail-la0-f53.google.com with SMTP id gl10so2048423lab.26
	for <qemu-devel@nongnu.org>; Thu, 31 Jul 2014 07:00:05 -0700 (PDT)
MIME-Version: 1.0
In-Reply-To: <20140731135501.GH2405@work-vm>
References: <1406809740-10836-1-git-send-email-arei.gonglei@huawei.com>
	<1406809740-10836-5-git-send-email-arei.gonglei@huawei.com>
	<20140731135501.GH2405@work-vm>
From: Peter Maydell <peter.maydell@linaro.org>
Date: Thu, 31 Jul 2014 14:59:45 +0100
Message-ID: <CAFEAcA_jCdw0GZCTyDoOty73qoc-RJB9-QU5GoefiN=tLSUCvA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Subject: Re: [Qemu-devel] [PATCH 4/7] a trivial code change for more
	idiomatic writing style
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: "Huangweidong (C)" <weidong.huang@huawei.com>, Stefan Hajnoczi <stefanha@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.a@redhat.com>, Luonengjun <luonengjun@huawei.com>, QEMU Developers <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>, "Gonglei (Arei)" <arei.gonglei@huawei.com>, Vassili Karpov <av1474@comtv.ru>, Gerd Hoffmann <kraxel@redhat.com>, Anthony Liguori <aliguori@amazon.com>, Igor Mammedov <imammedo@redhat.com>, Dmitry Fleytman <dmitry@daynix.com>, Paolo Bonzini <pbonzini@redhat.com>, peter.huangpeng@huawei.com, Luiz Capitulino <lcapitulino@redhat.com>, =?UTF-8?Q?Andreas_F=C3=A4rber?= <afaerber@suse.de>

On 31 July 2014 14:55, Dr. David Alan Gilbert <dgilbert@redhat.com> wrote:
> * arei.gonglei@huawei.com (arei.gonglei@huawei.com) wrote:
>> --- a/qdev-monitor.c
>> +++ b/qdev-monitor.c
>> @@ -694,7 +694,7 @@ void qmp_device_del(const char *id, Error **errp)
>>      DeviceState *dev;
>>
>>      dev = qdev_find_recursive(sysbus_get_default(), id);
>> -    if (NULL == dev) {
>> +    if (dev == NULL) {
>
> I know people who write it as 'NULL == dev' on purpose,
> because that will cause an error if you accidentally type a single =
> where as 'dev = NULL'  will just cause confusion.

Yes, this is the motivation for Yoda conditionals. But it only
makes sense if you don't have a compiler with a sensible
warning configuration. For QEMU you will get an error if you
write "dev = NULL" :

error: suggest parentheses around assignment used as truth value
[-Werror=parentheses]

so we don't need to get people to contort their code like this.

thanks
-- PMM