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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 8408CE7DF0F for ; Mon, 2 Feb 2026 17:50:24 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vmy40-00063V-5j; Mon, 02 Feb 2026 12:50:16 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vmy3v-000638-CY for qemu-devel@nongnu.org; Mon, 02 Feb 2026 12:50:11 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vmy3s-0007fH-Ne for qemu-devel@nongnu.org; Mon, 02 Feb 2026 12:50:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770054606; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FOVYdV2w2vYA+FkLELyAyaP7KNjNYKtLwJr5nCNNYWA=; b=bYEqcPyKOm3Xkz1KsYEGR55q7uo5gycJX4X2Aqqg6Kakc+PJ/rpqLnPLWy2iYYqp4ZORtN IXRd2z5eJEGrbd0OxRWScQb12udl2KWZGXy66tBJ8dWTjLlbxe6QNeY7nkZNPL95q8Wzct AVyIGj69QgOSv25IgHfPJkAEhtK5VNk= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-45-Hd56CxugOZ-1djW9IqKGRg-1; Mon, 02 Feb 2026 12:49:41 -0500 X-MC-Unique: Hd56CxugOZ-1djW9IqKGRg-1 X-Mimecast-MFC-AGG-ID: Hd56CxugOZ-1djW9IqKGRg_1770054580 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9F02818002D7; Mon, 2 Feb 2026 17:49:40 +0000 (UTC) Received: from redhat.com (unknown [10.45.226.68]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4101819560B2; Mon, 2 Feb 2026 17:49:37 +0000 (UTC) Date: Mon, 2 Feb 2026 17:49:34 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Pierrick Bouvier Cc: Mark Cave-Ayland , Cornelia Huck , Peter Maydell , Richard Henderson , qemu-devel@nongnu.org Subject: Re: [PULL 00/21] Plugins patches for 2026-01-29 Message-ID: References: <20260129173811.138036-1-pierrick.bouvier@linaro.org> <2d69de6e-da9f-4f90-b805-9553bb72c78d@linaro.org> <7ac8fe1f-8098-4417-a97b-1a82c0fd23ca@linaro.org> <878qdbtam7.fsf@redhat.com> <23be2c83-01ea-495d-b14e-496bd3e0a687@nutanix.com> <416762ea-471d-4e7d-8e02-d350c01dc8fd@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <416762ea-471d-4e7d-8e02-d350c01dc8fd@linaro.org> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Feb 02, 2026 at 09:45:52AM -0800, Pierrick Bouvier wrote: > On 2/2/26 9:34 AM, Daniel P. Berrangé wrote: > > On Mon, Feb 02, 2026 at 09:30:31AM -0800, Pierrick Bouvier wrote: > > > On 2/2/26 8:55 AM, Mark Cave-Ayland wrote: > > > > On 02/02/2026 15:42, Cornelia Huck wrote: > > > > > > > > > On Mon, Feb 02 2026, Peter Maydell wrote: > > > > > > > > > > > On Mon, 2 Feb 2026 at 04:04, Richard Henderson > > > > > > wrote: > > > > > > > > > > > > > > On 1/30/26 04:41, Pierrick Bouvier wrote: > > > > > > > > On 1/29/26 9:37 AM, Pierrick Bouvier wrote: > > > > > > > > > contrib/plugins: add empty cpp plugin > > > > > > > > > > > > Hi; this fails to build for me on Linux (Ubuntu 24.04) with clang: > > > > > > > > > > > > In file included from ../../contrib/plugins/cpp.cpp:33: > > > > > > /usr/bin/../lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/coroutine:38:3: > > > > > > error: "the header requires -fcoroutines" > > > > > > 38 | # error "the header requires -fcoroutines" > > > > > > | ^ > > > > > > 1 error generated. > > > > > > > > > > Fails for me as well on Fedora 42 (x86_64) with gcc: > > > > > > > > > > In file included from ../qemu/contrib/plugins/cpp.cpp:33: > > > > > /usr/include/c++/15/coroutine:43:3: error: #error "the header requires -fcoroutines" > > > > > 43 | # error "the header requires -fcoroutines" > > > > > | ^~~~~ > > > > > > > > > > (It works for me on an aarch64 RHEL 9 system.) > > > > > > > > Is this with a clean build? I had exactly the same error message > > > > earlier, but I was able to fix it by destroying my build/ directory, > > > > then re-running configure followed again by make. > > > > > > > > > > Thanks for the reports everyone. > > > > > > I tried it on ubuntu LTS and didn't encounter this problem. > > > What is happening is that meson unfortunately caches default_options set, > > > including the C++ standard version in our case. > > > Thus, you indeed need to clean and rebuild once. > > > > > > The solution for this would be to not use default_options and add the flag > > > to qemu_cflags instead. It's the same limitation if we change the default > > > warning level, or any other option set with default_options. > > > > If that's correct as the root cause, then it feels like this is a meson bug > > that ought to be reported upstream. Any meson.build default_options changes > > that affect the compiler behaviour should invalidate cache in the same way > > as when we modify qemu_cflags. > > > > I totally agree with you Daniel, and I've been bitten by that in my previous > company when updating cpp standard we used. As you can see, it slipped out > of my mind for current series... > > I never understood why it had this counter intuitive behaviour, and didn't > bother to report to be honest, I simply switched to manual flags instead at > the time. > Meson devs usually have a strong opinion of how things should be, so I don't > expect this to be something that fell through the cracks but a deliberate > design choice. > > EDIT: after typing the answer above, did a quick search, and indeed, it's > how it's supposed to be. So be it. > https://github.com/mesonbuild/meson/issues/13556 That's been marked a dupe of: https://github.com/mesonbuild/meson/issues/2193 where Paolo says recent refactoring has (finally) made fixing this problem a pratical task.... but that was 6+ months ago still, so guess we'll have to wait a while yet. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|