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 C2FEDD30004 for ; Fri, 18 Oct 2024 13:10:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t1mkB-00064l-Vd; Fri, 18 Oct 2024 09:10:15 -0400 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 1t1mkB-00063b-AG for qemu-devel@nongnu.org; Fri, 18 Oct 2024 09:10:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1t1mk6-0004PP-Gb for qemu-devel@nongnu.org; Fri, 18 Oct 2024 09:10:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1729257008; 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: in-reply-to:in-reply-to:references:references; bh=lMjrOGFmVI50rdu0SKya0KWK9sRXrS7uZtsgOjBNZug=; b=YuYepCfGp+IGXo8M5tAqSzVlJkW/d+uoxtDW9u6+5VBzCAKRLWRhTE9Cdsd4fffvooRtgE bq/8D6p/6tETcDrzYYjSzp5aD7763F4uvg/lNhFxKMZnqcymL3oktIBNiliNrghVmOr8SV yvh/EPIiusZDyPMNwqokGvy2zoB9t5k= Received: from mx-prod-mc-05.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-652-_S4VzmqUN_mKz36bluwoWA-1; Fri, 18 Oct 2024 09:10:02 -0400 X-MC-Unique: _S4VzmqUN_mKz36bluwoWA-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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A7463195608D for ; Fri, 18 Oct 2024 13:10:01 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.196]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A348B19560A2; Fri, 18 Oct 2024 13:10:00 +0000 (UTC) Date: Fri, 18 Oct 2024 15:09:58 +0200 From: Kevin Wolf To: Paolo Bonzini Cc: qemu-devel@nongnu.org Subject: Re: [RFC PATCH 00/16] rust: allow older versions of rustc and bindgen Message-ID: References: <20241015131735.518771-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241015131735.518771-1-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@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=-0.016, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_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 Am 15.10.2024 um 15:17 hat Paolo Bonzini geschrieben: > This includes a few fixes to the Rust build system machinery, and > removes constructs that were added or stabilized after version 1.63.0: Most of this series looks harmless in the sense that we need to write some workaround code in a single place and can forget about it. So that's good. > - "let else" (by patching bilge-impl, patch 4; stable in 1.65.0) This one affects all of the code we'll write and the replacement is a bit unwieldy. It might be the most annoying one from the list. > - std::sync::OnceLock (patch 6; stable in 1.70.0) > > - core::ffi (patch 7; stable in 1.64.0) > > - c"" literals (patch 9; stable in 1.77.0) This one will be fairly widespread, too, but only a minor inconvenience. > - offset_of! (patch 10; stable in 1.77.0) Requiring structs to be wrapped in with_offsets! has potential to become quite annoying, too, but it seems we already have a solution for this with the proc macro. > - MaybeUninit::zeroed() (patch 11; stable in 1.75.0 in const context) > > It also replicates the configuration checks normally done by > proc-macro2's build.rs into our Meson-based build rules, so that > the crate can be made to work with an older version of rustc. > > As a small bonus, patch 11 removes some uses of unsafe, so that patch > probably won't just be simply reverted even once we can assume version > 1.75.0 of the language. And as another small bonus this series introduces > the first use of Rust unit tests. > > On top of this, the required version of bindgen is still too new > for Debian 12 and Ubuntu 22.04. This is fixed by the last four patches. > > This is an RFC for two reasons. First, because it would be a valid > decision to delay enabling of Rust until at least some of these > features are available in all supported distros. Another possibility > could be to accept Rust 1.64.0 but require installing a newer bindgen > (0.66.x for example) on those two distros with an older release. Second, > because the series is missing the CI updates to actually ensure that > these minimum versions keep working. > > The main purpose is to show the kind of hacks that would be needed > to support older toolchains. The fixes (for example patches > 1/2/3/6/8/11/13/14) can be easily extracted independent of the outcome > of the discussion, and/or while the CI updates are made. It would probably make sense to just go ahead and apply the fixes. They seem a lot more obvious than the question which toolchains we want to support. Kevin