220 36360 <5300cf40-f7db-4eb6-ad36-4742855124ae@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: "mrpi via ISO C++ Standard - Future Proposals" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Default assignment operators for std::pair and std::tuple Date: Tue, 26 Dec 2017 10:37:07 -0800 (PST) Lines: 130 Approved: news@gmane.org Message-ID: <5300cf40-f7db-4eb6-ad36-4742855124ae@isocpp.org> References: <4110e47f-a021-4ccc-9e03-53e4ebdb8c21@isocpp.org> <4605434.q3o9RnjlYE@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_19163_695658782.1514313427800" X-Trace: blaine.gmane.org 1514313313 7582 195.159.176.226 (26 Dec 2017 18:35:13 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 26 Dec 2017 18:35:13 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDH2LIF7UEOBBVNNRLJAKGQEPUYOREY@isocpp.org Tue Dec 26 19:35:09 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f200.google.com ([209.85.217.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eTu4B-0001V9-Id for gclcip-std-proposals@m.gmane.org; Tue, 26 Dec 2017 19:35:07 +0100 Original-Received: by mail-ua0-f200.google.com with SMTP id b42sf12065656uah.20 for ; Tue, 26 Dec 2017 10:37:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=tZ46elqoNTEaPKEXN6IdsLPbCjX2jrJ8TFYtiRaTZFQ=; b=l+i3z7RiPF77h0jiYXsh8aD2lxGyGgGbVa+WluPYbImHUciG/A4LHlg+JKC5yxZetl 5Gnb7H5C0V5sLXfSFdRASDZ7ImQmiQWeHPnmsv5JPOLA6kom/naoF34vQqmTj2pxOqMo 5syZNCMDyRsYf1u8hKB658REH+x6Jcxpch19btOvFcW3HygcRl9GjPnW56UFTNBj/3DA 0w5ZwDzkKvAT8OHvE5DeZQMYymZCJ+AIXFmiIyuZgx/nAN7m6jSapBy/LlQdkrrAaspP 0rX0v8Guv4y1MSYO2LjsEn8x4pljOYI8QOS05Tjz6gX9XDgp+aET6umHY13REordTn6d LyRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=tZ46elqoNTEaPKEXN6IdsLPbCjX2jrJ8TFYtiRaTZFQ=; b=qUTZe1ZwFUTFxNSXdP+6Za12Fl0tJdHdJJCtdZdjHj08zOj1JISARjrhuU47t1yocX RvLjVuS8F09W+mISzrH5svDf8Jb2/7SIK4rjrdwtVyLWj7ih5GPxwpGVnuY8WRm3+dKf MBOVx4B4+SP0BiIHGlWpEC4gvoMEXMj5BlPA6I3V3SJNc4FSFw33LpvJ576GbM36616a KAoUlIaIf2FwaocPujoj+oZrlHimQrx7xSjZ1tZMW3g/TI6jeEq2QaIZ1NaHqj3cETG2 QkLRbWZLNJ/F5alJdbtczMbk9SExFdoVk1P//zmF0rqUawCD7n1yhAxZnKhemYwnHDQF UtgA== X-Gm-Message-State: AKGB3mLvmlYUCvnqush/CJM5hf1yn7n8I/yWUrmfI8kX97UxycPK7x/K dgb3UAkNJEwoBHkpG8zpcK233Q== X-Google-Smtp-Source: ACJfBotQxfy3R5oe8uRet+rmEz0S8HHg9Eg0XE/Vm2tUj3z95FpRSOWdYUlwoLHiT6IeMKxGp8Dtng== X-Received: by 10.176.81.241 with SMTP id h46mr13898232uaa.104.1514313430268; Tue, 26 Dec 2017 10:37:10 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.79.65 with SMTP id d62ls382655vkb.1.gmail; Tue, 26 Dec 2017 10:37:08 -0800 (PST) X-Received: by 10.31.165.202 with SMTP id o193mr2417391vke.9.1514313428319; Tue, 26 Dec 2017 10:37:08 -0800 (PST) In-Reply-To: <4605434.q3o9RnjlYE@tjmaciei-mobl1> X-Original-Sender: mrpi@google.com X-Original-From: mrpi@google.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:36360 Archived-At: ------=_Part_19163_695658782.1514313427800 Content-Type: multipart/alternative; boundary="----=_Part_19164_1830722837.1514313427800" ------=_Part_19164_1830722837.1514313427800 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable How would it be an ABI break/change if the standard never specified if it= =20 was trivially copyable or not? In the first place, the discrepancy between= =20 different compilers on whether these two classes are trivially copyable is= =20 because of such a lack of clarity on that part, so what I'm asking for is a= =20 proposal to make them clearly use default assignment operators. Furthermore, I can't see how changing a type from being not trivially=20 copyable to being trivially copyable would be a problem. If so, then the=20 entire recent discussion about optionals and variants=20 would=20 be moot (for which those classes are also currently not guaranteed to use= =20 default copy/move constructors/assignments and not guaranteed trivially=20 copyable). On Tuesday, December 26, 2017 at 10:11:20 AM UTC-8, Thiago Macieira wrote: > > On ter=C3=A7a-feira, 26 de dezembro de 2017 13:02:05 -02 mrpi via ISO C++= =20 > Standard=20 > - Future Proposals wrote:=20 > > Sorry, I might not be understanding it correctly, but in what way would= =20 > it=20 > > be an ABI break, given that reference types are not trivially copyable= =20 > > anyways?=20 > > Changing a type from trivially copyable to not, or vice-versa, is the ABI= =20 > change.=20 > > --=20 > Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org=20 > Software Architect - Intel Open Source Technology Center=20 > > --=20 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 e= mail 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/5300cf40-f7db-4eb6-ad36-4742855124ae%40isocpp.or= g. ------=_Part_19164_1830722837.1514313427800 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
How would it be an ABI break/change if the standard never = specified if it was trivially copyable or not? In the first place, the disc= repancy between different compilers on whether these two classes are trivia= lly copyable is because of such a lack of clarity on that part, so what I&#= 39;m asking for is a proposal to make them clearly use default assignment o= perators.

Furthermore, I can't see how changing= a type from being not trivially copyable to being trivially copyable would= be a problem. If so, then the entire recent discussion about optionals and variants=C2=A0would be moot (for which those classes a= re also currently not guaranteed to use default copy/move constructors/assi= gnments and not guaranteed trivially copyable).

On Tuesday, Dec= ember 26, 2017 at 10:11:20 AM UTC-8, Thiago Macieira wrote:
On ter=C3=A7a-feira, 26 de dezembro de 2017 13= :02:05 -02 mrpi via ISO C++ Standard=20
- Future Proposals wrote:
> Sorry, I might not be understanding it correctly, but in what way = would it
> be an ABI break, given that reference types are not trivially copy= able
> anyways?

Changing a type from trivially copyable to not, or vice-versa, is the A= BI=20
change.

--=20
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
=C2=A0 =C2=A0Software Architect - Intel Open Source Technology Center

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You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+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/5300cf40-f7db-4eb6-ad36-4742855124ae= %40isocpp.org.
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