From patchwork Tue Nov 5 15:01:14 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= X-Patchwork-Id: 13863056 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 3DB3ED2C11E for ; Tue, 5 Nov 2024 15:02:35 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t8L3r-00008r-92; Tue, 05 Nov 2024 10:01:39 -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 1t8L3g-00007w-4m for qemu-devel@nongnu.org; Tue, 05 Nov 2024 10:01:29 -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 1t8L3b-0000gi-MJ for qemu-devel@nongnu.org; Tue, 05 Nov 2024 10:01:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1730818881; h=from:from: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; bh=Al8uMIy4idSHQy73devQTh7tjClJ9L57DftFqIg+cU8=; b=NtAzZwyTjAl7Jc5h1z2+Z5wu4BJggSP6aK5KU+BVnB3suo3rBjX3cs+xJ8ruBvNglWCAsO lghU/j+dI3Zb0ouC655aWJ8jXrbqD9i5/R2+1l7JEpx1dOtULrQi8Ja25paBHXqI1QaNJI py9smF7KBx5kA+N71BEMLuYrps2mG/k= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-531-ke3du5JlMHGbgLKaXHxhHg-1; Tue, 05 Nov 2024 10:01:19 -0500 X-MC-Unique: ke3du5JlMHGbgLKaXHxhHg-1 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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CEEB61954B1C; Tue, 5 Nov 2024 15:01:18 +0000 (UTC) Received: from toolbox.redhat.com (unknown [10.42.28.52]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 2ED5119560AE; Tue, 5 Nov 2024 15:01:16 +0000 (UTC) From: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= To: qemu-devel@nongnu.org Cc: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , =?utf-8?q?M?= =?utf-8?q?arc-Andr=C3=A9_Lureau?= , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Paolo Bonzini Subject: [PATCH] meson: explain more verbosely why we forbid Clang on Windows Date: Tue, 5 Nov 2024 15:01:14 +0000 Message-ID: <20241105150114.334985-1-berrange@redhat.com> MIME-Version: 1.0 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: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.34, 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_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=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: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Contributors are repeatedly sending patches to remove the blockage of clang on Windows, ignoring that we need 'gcc_struct' support. Put some more explicit comments in the code to discourage people from doing this. Signed-off-by: Daniel P. Berrangé Reviewed-by: Richard Henderson --- include/qemu/compiler.h | 7 +++++++ meson.build | 11 ++++++++++- 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index c06954ccb4..38ed8997ca 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -22,6 +22,13 @@ #define QEMU_EXTERN_C extern #endif +/* + * QEMU requires 'gcc_struct' on Windows for correct guest ABI. + * meson.build checks for 'gcc_struct' and blocks use of CLang + * on Windows, pending a fix for: + * + * https://github.com/llvm/llvm-project/issues/24757 + */ #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) # define QEMU_PACKED __attribute__((gcc_struct, packed)) #else diff --git a/meson.build b/meson.build index 2c9086a3fe..37b7daa758 100644 --- a/meson.build +++ b/meson.build @@ -330,9 +330,18 @@ elif host_os == 'sunos' elif host_os == 'haiku' qemu_common_flags += ['-DB_USE_POSITIVE_POSIX_ERRORS', '-D_BSD_SOURCE', '-fPIC'] elif host_os == 'windows' + # Clang is blocked, pending impl of 'gcc_struct' support: + # + # https://gitlab.com/qemu-project/qemu/-/issues/2476 + # https://github.com/llvm/llvm-project/issues/24757 + # https://github.com/llvm/llvm-project/pull/71148 + # + # Once the above is available this check should "do the right thing". + # This check can then eventually be removed once the CLang minimum + # version checked 50 lines earlier guarantees support if not compiler.compiles('struct x { int y; } __attribute__((gcc_struct));', args: '-Werror') - error('Your compiler does not support __attribute__((gcc_struct)) - please use GCC instead of Clang') + error('Your compiler does not support __attribute__((gcc_struct)) - please use GCC instead of Clang (https://github.com/llvm/llvm-project/issues/24757)') endif endif