From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34047) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fGmhb-0006Iu-Mh for qemu-devel@nongnu.org; Thu, 10 May 2018 10:37:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fGmhX-0000AT-NW for qemu-devel@nongnu.org; Thu, 10 May 2018 10:37:51 -0400 Received: from mail-pl0-x242.google.com ([2607:f8b0:400e:c01::242]:33856) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fGmhX-0000AH-HU for qemu-devel@nongnu.org; Thu, 10 May 2018 10:37:47 -0400 Received: by mail-pl0-x242.google.com with SMTP id ay10-v6so1430723plb.1 for ; Thu, 10 May 2018 07:37:47 -0700 (PDT) Sender: Richard Henderson References: <20180510143618.23673-1-peter.maydell@linaro.org> From: Richard Henderson Message-ID: Date: Thu, 10 May 2018 07:37:44 -0700 MIME-Version: 1.0 In-Reply-To: <20180510143618.23673-1-peter.maydell@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] atomic.h: Work around gcc spurious "unused value" warning List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell , qemu-devel@nongnu.org Cc: patches@linaro.org, Paolo Bonzini On 05/10/2018 07:36 AM, Peter Maydell wrote: > Some versions of gcc produce a spurious warning if the result of > __atomic_compare_echange_n() is not used and the type involved > is a signed 8 bit value: > error: value computed is not used [-Werror=unused-value] > This has been seen on at least > gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609 > > Work around this by using an explicit cast to void to indicate > that we don't care about the return value. > > We don't currently use our atomic_cmpxchg() macro on any signed > 8 bit types, but the upcoming support for the Arm v8.1-Atomics > will require it. > > Signed-off-by: Peter Maydell > --- > Sending out my workaround as an actual patch. If this is OK I'll > put in via target-arm.next as it's a dependency for the v8.1-atomics > series. > > include/qemu/atomic.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Richard Henderson r~