From owner-freebsd-hackers@freebsd.org Thu Feb 20 04:28:13 2020 Return-Path: Delivered-To: freebsd-hackers@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 8DAF1252A0E for ; Thu, 20 Feb 2020 04:28:13 +0000 (UTC) (envelope-from lichray@gmail.com) Received: from mail-io1-xd31.google.com (mail-io1-xd31.google.com [IPv6:2607:f8b0:4864:20::d31]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 48NM5m0l3wz4Bl2 for ; Thu, 20 Feb 2020 04:28:11 +0000 (UTC) (envelope-from lichray@gmail.com) Received: by mail-io1-xd31.google.com with SMTP id z16so3148967iod.11 for ; Wed, 19 Feb 2020 20:28:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=v9l+yaF07+xrhvIb4HVGbD7I6KEmQ9Rg1YkRUgXMdSg=; b=olplb6/F62DgQiHp5Oi3c2R+Hcg9v5PjYX2k9OxQelrem61l3jzyfm0iwi3qaur6aP vVM9rEci5+T4bNK+u08CgqaRJPOn1YBhYuwApviXi5j/F9MRwX52Ish56YDtnzgiEiHN dpx+mjq1B4imZR8h0A6RkVoag3JgHG/+E5Hr7VVPSyDo9vkQJgENTbMoBw1nyYUUIywZ c/wnNpLNMDR5SBlbH0MdHN0A04+v1FjR+sJe6seSDn45ZiYMkTskhYiCgESt9tAVB2Fr 6H0kO36m3kTKvrE33Zp9MV5R02+0CYAkkCx6JauWw6QLgX9ieKsGJZGPGId3EJCvyl28 M03g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=v9l+yaF07+xrhvIb4HVGbD7I6KEmQ9Rg1YkRUgXMdSg=; b=kbqKeiaI7C6SdaVUcpKOxlM/+T90FZTW89ESnqIjMGA35Wj5hHkQe9kFXPzEp5UK5v 1tzQBOXKGY8fdXbuXbJ1vSTVzknWWBjvHGq7BWp58j2NIP4Y9NJmvMngGOZ4ccKTAsvn rZiVlJyWKwlFseyNVyw6cQsEAF5GMgN/KFzUFKJoJD6ERWOLnCGgAJoM582ilUfuIOmU AbbxqqIPNCeStZL8bBlNi36Sa/hGze9AMq9iSyNVSrL8A7xgMkbkrYohaixFxsqqiZPL wkVsr2engCuE81q3hro8aEjFxLX6D60i9f+pDJ15lHt7Hi1O8yeu2ogRbeBrqYF3VLnw qHTQ== X-Gm-Message-State: APjAAAW5oF0GqQrh7NF1c5DjJxldYae/ES/8B7pv7uESJiNTBLwsKwAr ZOFt9NuQ9qOrFsKBQqjJBXIxj++ytf7o9kPrvNMnOQ/FSFI= X-Google-Smtp-Source: APXvYqx7o9t5WNP/bTtyospiqj3cVGzUZArq2uvIe/JXl3qV8DssqbOkYVvfr4xywOwNIVYul49ExeJCk2rGpIEVzME= X-Received: by 2002:a5d:8892:: with SMTP id d18mr21053289ioo.59.1582172888360; Wed, 19 Feb 2020 20:28:08 -0800 (PST) MIME-Version: 1.0 From: Zhihao Yuan Date: Wed, 19 Feb 2020 22:27:57 -0600 Message-ID: Subject: How much libc++ ABI changes FreeBSD can consume? To: FreeBSD Hackers X-Rspamd-Queue-Id: 48NM5m0l3wz4Bl2 X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=olplb6/F; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of lichray@gmail.com designates 2607:f8b0:4864:20::d31 as permitted sender) smtp.mailfrom=lichray@gmail.com X-Spamd-Result: default: False [-2.00 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36:c]; FREEMAIL_FROM(0.00)[gmail.com]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; IP_SCORE_FREEMAIL(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; SUBJECT_ENDS_QUESTION(1.00)[]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; RCVD_IN_DNSWL_NONE(0.00)[1.3.d.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.b.8.f.7.0.6.2.list.dnswl.org : 127.0.5.0]; TO_MATCH_ENVRCPT_ALL(0.00)[]; IP_SCORE(0.00)[ip: (-6.55), ipnet: 2607:f8b0::/32(-1.89), asn: 15169(-1.67), country: US(-0.05)]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Feb 2020 04:28:13 -0000 Hi, I'm sending this email because a. FreeBSD has been stuck on libc++ V1 ABI long enough. I would like to learn some details. b. There is an ongoing discussion in the C++ standards committee talking about whether the standard library should break ABI on a regular basis. Here are my questions: 1. Is FreeBSD waiting for libc++ V2 ABI to freeze? If so, will FreeBSD switch to V2 ABI afterwards? 2. The pkgs are tagged with __FreeBSD_version, is that enough to allow libc++ ABI to change at every FreeBSD (major) release? 3. Is MFC required for libc++ updates? If so, how does that affect ABI changes? 4. Is there any desire to make C++ ABI breakage smoother by ultilzing mechanisms such as Symbol.map? Thanks, -- Zhihao Yuan, ID lichray The best way to predict the future is to invent it. _______________________________________________