From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47376) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fWNKi-0001fE-7w for qemu-devel@nongnu.org; Fri, 22 Jun 2018 10:46:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fWNKh-0004vP-Em for qemu-devel@nongnu.org; Fri, 22 Jun 2018 10:46:40 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:36412 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 1fWNKh-0004vJ-9l for qemu-devel@nongnu.org; Fri, 22 Jun 2018 10:46:39 -0400 References: <20180621145749.191944-1-eblake@redhat.com> <5db29b95-c79b-9766-81c8-360cdd0a5b94@redhat.com> From: Eric Blake Message-ID: <6f1a7d16-79af-aa06-af33-e349a08aa53e@redhat.com> Date: Fri, 22 Jun 2018 09:46:37 -0500 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PULL v2 0/9] bitmap export over NBD List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: QEMU Developers On 06/22/2018 07:13 AM, Peter Maydell wrote: > On 22 June 2018 at 13:12, Eric Blake wrote: >> Uurgh. It's a false positive (the compiler is complaining that the variable >> is uninitialized, which can only happen if the while loop is not executed; >> but the preconditions guarantee the loop executes at least once). The >> assert() that I added was enough to silence gcc 7.3.1 on my Fedora 27 >> system, but docker-mingw@fedora is using gcc-8.1.1-1.fc28.x86_64. This >> should silence things (another way to silence would be rewriting while{} >> into do{}while). I'll submit this as a formal patch if I can reproduce the >> problem/fix on docker. > > Huh. I had thought this was an old-gcc problem, not a new-gcc > one. Might be worth submitting to the gcc folks as a regression... Hmm, I couldn't quickly reproduce it with a direct gcc on Fedora 28; and I don't know docker well enough to know if the cross-gcc used in docker-mingw@fedora is a different version than the native gcc-8.1.1 listed in the installed packages list (the patchew output doesn't list the version of x86_64-w64-mingw32-gcc). Thus, I can't tell if it is a recent gcc regression or merely an old-gcc issue. But I can confirm that 'make docker-test-mingw@fedora' reproduced the problem without my cleanup patch, and that my cleanup patch now in master made that happy again. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org