220 31698 article Path: news.gmane.org!.POSTED!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Simplify virtual inheritance rules Date: Sun, 19 Mar 2017 20:12:25 +0200 Lines: 23 Approved: news@gmane.org Message-ID: References: <6aa2e439-345e-4f04-8843-f38bb7b825b2@isocpp.org> <25e054ca-aac4-4bcc-805a-4e1357de4f37@isocpp.org> <1785771.9FtZOUdvrM@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: blaine.gmane.org 1489947153 9210 195.159.176.226 (19 Mar 2017 18:12:33 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 19 Mar 2017 18:12:33 +0000 (UTC) To: "ISO C++ Standard - Future Proposals" Original-X-From: std-proposals+bncBC5JHI7A7ALRBCMUXPDAKGQER2AQNPI@isocpp.org Sun Mar 19 19:12:28 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pf0-f197.google.com ([209.85.192.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cpfJU-0001AG-PC for gclcip-std-proposals@m.gmane.org; Sun, 19 Mar 2017 19:12:20 +0100 Original-Received: by mail-pf0-f197.google.com with SMTP id y6sf208251492pfa.3 for ; Sun, 19 Mar 2017 11:12:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=390AAIk8N0Qha9vhsqQlOU1K0A0JD+1Zqs+7hdWQ920=; b=j59TNdmsTYGYbI7obhaXklhsCEbbz9yg8ytIhb37Ry9cGa39Aog4r5FieBqeoeWOAK jY9+5sR+nq+8/D0bVeZw5UbiOtXBXVxDzS4PuQfuo1O7JSPinhklbBBegcMPwHqqCPnV YGRg3rUW4bqpVSlyoRs7c6QnLe58sHNQcQbD9SxjAKGS85hBOQwHUgiKhJ76wDC7hY+b xf9G5E6QRgDkrpe8bekxQFKRYgTc/OUH6RMhMXHR2CLyT9vbJatVSNtT9We1AcJ6TpTD ZCHg4YayFxqmtlAFOZY+ZR9wMDVzpRBB2PT3Cr/kymOG/jlNAYWVSMtEI39gW6hdwwqz SXjA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=390AAIk8N0Qha9vhsqQlOU1K0A0JD+1Zqs+7hdWQ920=; b=ApyhNvNWtY4EG/+PCntABr1DfenxR5XESF/KOlzjbm0xvchnNjYvFxIADhW5VC1iS9 SqRGZjRLY5Ubi1HB5cnLYsJmkVYSsIouzWsFz+PpXrd1J/wMSUbeKDlUNEco8Ooiddhx TKHDaopt8TjAO0ekwcblgpmlX91snRhvQb+l5jlyiHpOpPbR08zsrh0P9uHMhkU2rw27 il9nIM0LjKOj/Nmg/LETs6Q2RsnZnr3kf2jO8ApOD6Ufl7OMWxYJfBzrBQdADt9SfTBP NRxEt/wDANpMtHFbmjrEfxKHHalyui4XzAx28xYlzt8K+eqqfZIVqC7dE3/X+t8snZff dCJg== X-Gm-Message-State: AFeK/H3yuzYT9NUEf3Vqkt0d2s9ZF4VTQxOomroYfEKZjCb5y0gLvg5iIlK1Q+T7Q4L2Xw== X-Received: by 10.99.110.1 with SMTP id j1mr14191100pgc.52.1489947146482; Sun, 19 Mar 2017 11:12:26 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.56.232 with SMTP id k37ls12168938ote.15.gmail; Sun, 19 Mar 2017 11:12:25 -0700 (PDT) X-Received: by 10.157.48.59 with SMTP id d56mr13153291otc.81.1489947145764; Sun, 19 Mar 2017 11:12:25 -0700 (PDT) Original-Received: from mail-oi0-x22c.google.com (mail-oi0-x22c.google.com. [2607:f8b0:4003:c06::22c]) by mx.google.com with ESMTPS id m36si5939861otd.144.2017.03.19.11.12.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 19 Mar 2017 11:12:25 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:4003:c06::22c as permitted sender) client-ip=2607:f8b0:4003:c06::22c; Original-Received: by mail-oi0-x22c.google.com with SMTP id w81so13844157oig.1 for ; Sun, 19 Mar 2017 11:12:25 -0700 (PDT) X-Received: by 10.202.54.4 with SMTP id d4mr13652475oia.45.1489947145465; Sun, 19 Mar 2017 11:12:25 -0700 (PDT) Original-Received: by 10.157.13.22 with HTTP; Sun, 19 Mar 2017 11:12:25 -0700 (PDT) In-Reply-To: <1785771.9FtZOUdvrM@tjmaciei-mobl1> X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:4003:c06::22c as permitted sender) smtp.mailfrom=ville.voutilainen@gmail.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:31698 Archived-At: On 19 March 2017 at 19:58, Thiago Macieira wrote: >> The language statically guarantees that the initialization of the >> VirtualBase is performed. Your >> suggestion turns that static guarantee into undefined behavior. > > The complete constructor must exist if the direct base class is not abstract. > In other words, the complete constructor must exist if a user is able to > construct that class. > > The compiler will have to emit the base object constructor for all of those > classes, since another class down the line could choose to construct the > virtual base directly. Right, so this proposal doesn't produce UB. That leaves the other compatibility issues. -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAFk2RUZ1xwEG_L-LG-FE9oKoDeEbVmBqvc6LRwdnOeWV%2BKENgw%40mail.gmail.com. .