220 40100 article Path: news.gmane.org!.POSTED!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Named Parameters for C++ Date: Thu, 30 Aug 2018 01:24:41 +0300 Lines: 32 Approved: news@gmane.org Message-ID: References: <735cf8f8-41e8-49b3-9dec-1ff47e2a47f8@isocpp.org> 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 1535581361 27867 195.159.176.226 (29 Aug 2018 22:22:41 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 29 Aug 2018 22:22:41 +0000 (UTC) To: "ISO C++ Standard - Future Proposals" Original-X-From: std-proposals+bncBC5JHI7A7ALRBK52TTOAKGQENKHR3UI@isocpp.org Thu Aug 30 00:22:37 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f72.google.com ([209.85.218.72]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fv8rC-00076D-A1 for gclcip-std-proposals@m.gmane.org; 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[209.85.220.41]) by mx.google.com with SMTPS id s2-v6sor3932533ois.37.2018.08.29.15.24.43 for (Google Transport Security); Wed, 29 Aug 2018 15:24:43 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:aca:e0c2:: with SMTP id x185-v6mr65436oig.220.1535581482640; Wed, 29 Aug 2018 15:24:42 -0700 (PDT) Original-Received: by 2002:a9d:176:0:0:0:0:0 with HTTP; Wed, 29 Aug 2018 15:24:41 -0700 (PDT) In-Reply-To: X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=jT4w60QV; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=ville.voutilainen@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:40100 Archived-At: On 30 August 2018 at 00:43, Zhihao Yuan wrote: >> From: Ville Voutilainen >> Sent: Wednesday, August 29, 2018 3:42 PM >> >> defining the order of evaluation >> seems perfectly palatable to me, because that's what we do for >> ctor-initializers, and I don't suppose >> it's all that hard implementation-wise either. > > The authors had extensive discussions on this topic > and copying what ctor-initializers did was certainly > considered, until we realized that the ctor-initializers > and the data members are both controlled by the class > authors, while only the data members are controlled by > the aggregate author since the uses of the designated > initializers are controlled by the aggregate users. This > difference can cause some code to legitimately and > silently fails at runtime if the aggregate changes the > member orders, making a library less sustainable. Ah, heh, there's indeed a UB component in it, because we can't statically guarantee that the members and their initializers wouldn't end up dependent. And we get into that UB-land even with trivial types. -- 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/CAFk2RUb4WGJaG7-b%3DdaPNhiDV9ZvvKwTH9ARqOoy9SmpdjFOrg%40mail.gmail.com. .