220 35023 article Path: news.gmane.org!.POSTED!not-for-mail From: "'Edward Catmur' via ISO C++ Standard - Future Proposals" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: standard attribute for unions to pun types? 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[209.85.220.41]) by mx.google.com with SMTPS id y66sor621126wmd.66.2017.10.19.14.11.35 for (Google Transport Security); Thu, 19 Oct 2017 14:11:35 -0700 (PDT) Received-SPF: pass (google.com: domain of ecatmur@googlemail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 10.28.143.130 with SMTP id r124mr2897364wmd.122.1508447495546; Thu, 19 Oct 2017 14:11:35 -0700 (PDT) Original-Received: by 10.28.52.145 with HTTP; Thu, 19 Oct 2017 14:11:34 -0700 (PDT) In-Reply-To: X-Original-Sender: ecatmur@googlemail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@googlemail.com header.s=20161025 header.b=kofHBo1J; spf=pass (google.com: domain of ecatmur@googlemail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=ecatmur@googlemail.com; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=googlemail.com X-Original-From: Edward Catmur 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:35023 Archived-At: --001a114696ba226e66055beccde2 Content-Type: text/plain; charset="UTF-8" On Thu, Oct 19, 2017 at 9:06 PM, Hyman Rosen wrote: > On Thu, Oct 19, 2017 at 12:34 PM, 'Edward Catmur' via ISO C++ Standard - > Future Proposals wrote: >> >> Are you aware of the bit_cast proposal? https://wg21.link/p0476 >> > > Can bit_cast return a reference to the From object reinterpreted as the To > object, > or is it strictly copied return value only? If the latter, it's just more > optimizationists > papering over what people really want to do. > References are not TriviallyCopyable, so the answer is no. I am sure that plenty of "what people really want to do" would be satisfied by bit_cast as presented. For example, the dtoa you mention above could readily be implemented in terms of a value-semantic bit_cast. -- 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/CAJnLdObZx2pvq2_Qk3M0kryekh%3D1zsMB%3DoP6vTYn8s%2Bi8BtaeQ%40mail.gmail.com. --001a114696ba226e66055beccde2 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On T= hu, Oct 19, 2017 at 9:06 PM, Hyman Rosen <hyman.rosen@gmail.com>= ; wrote:
On Thu, Oct = 19, 2017 at 12:34 PM, 'Edward Catmur' via ISO C++ Standard - Future= Proposals <std-proposals@isocpp.org> wrote:
Are you aware of the bit_cast proposal?=C2=A0https://wg21.link/p0476= =C2=A0

C= an bit_cast return a reference to the From object reinterpreted as the To o= bject,
or is it strictly copied return value only?=C2=A0 If the latter, = it's just more optimizationists
papering over what people really wan= t to do.

References= are not TriviallyCopyable, so the answer is no.

I= am sure that plenty of "what people really want to do" would be = satisfied by bit_cast as presented. For example, the dtoa you mention above= could readily be implemented in terms of a value-semantic bit_cast.
<= /div>

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