220 11790 article Path: news.gmane.org!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: N4078: Rvalue reference overloads for value() method returns object by value Date: Thu, 10 Jul 2014 09:31:40 +0300 Lines: 34 Approved: news@gmane.org Message-ID: References: <4DA018C3-2327-4F55-B7F8-7988EC7B789A@gmail.com> <1a858a77-310b-4591-aaf5-960c40d9f5fc@isocpp.org> <66AF41C1-CB37-4311-98EA-D47DBC6068DC@gmail.com> <66c38b61-7a95-4ace-b34f-2346bb334fb9@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1404973908 1269 80.91.229.3 (10 Jul 2014 06:31:48 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 10 Jul 2014 06:31:48 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5JHI7A7ALRBTHG7COQKGQENDXFPRI@isocpp.org Thu Jul 10 08:31:43 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yk0-f200.google.com ([209.85.160.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1X57tN-0001wd-Uz for gclcip-std-proposals@m.gmane.org; Thu, 10 Jul 2014 08:31:42 +0200 Original-Received: by mail-yk0-f200.google.com with SMTP id 20sf19748549yks.7 for ; Wed, 09 Jul 2014 23:31:41 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type; bh=J7wTRCW/MJ8tnVI/f1UDaFJw/62IxtkPhMkPxrL0leA=; b=FGLFhEZhRwHcrdZV4jkuQ3qd/OGkYGo8ZgKyLVsjqt3aJ5RV+G3JzewQP4+DTAafbI iOm+x+HKPzHzYajynYM0zLr0b9D4SDpSkpRUbZD3OCBpwnYgtyEul2LXtJDTrx2Euq2s NQkPqyIUuQuQ1ZXPkIOF81ndnZ9vPy+14/CWSU+5yX5M+cpkDsKNNipcbvPH8mx5WRac rLewUHi2/gZpT4JvASIfORj92/6JRE42D04tYjb1vE5+tqEx/wTcUrosjkVbSdVUa60J aVFygGoTRXCNuU1fVws0QpH5nlo8ieUm5cwJL6mweMB2LHvAl57aUX83w2w+/vFHDL4/ d2pQ== X-Gm-Message-State: ALoCoQnJJyreUnoQTqhw6DMNRHUOE4N9XS6cm8B69PrDrxQW9KfNxKK9RkglHqh+ZeS//vkCOXJ1 X-Received: by 10.224.41.74 with SMTP id n10mr21994427qae.1.1404973901130; Wed, 09 Jul 2014 23:31:41 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.101.23 with SMTP id t23ls2794739qge.32.gmail; Wed, 09 Jul 2014 23:31:40 -0700 (PDT) X-Received: by 10.140.84.168 with SMTP id l37mr74942444qgd.104.1404973900540; Wed, 09 Jul 2014 23:31:40 -0700 (PDT) Original-Received: from mail-qa0-x22a.google.com (mail-qa0-x22a.google.com [2607:f8b0:400d:c00::22a]) by mx.google.com with ESMTPS id q68si63359163qgd.14.2014.07.09.23.31.40 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 09 Jul 2014 23:31:40 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c00::22a as permitted sender) client-ip=2607:f8b0:400d:c00::22a; Original-Received: by mail-qa0-f42.google.com with SMTP id j15so1014630qaq.29 for ; Wed, 09 Jul 2014 23:31:40 -0700 (PDT) X-Received: by 10.140.87.236 with SMTP id r99mr6998809qgd.43.1404973900464; Wed, 09 Jul 2014 23:31:40 -0700 (PDT) Original-Received: by 10.224.31.137 with HTTP; Wed, 9 Jul 2014 23:31:40 -0700 (PDT) In-Reply-To: X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c00::22a as permitted sender) smtp.mail=ville.voutilainen@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=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:11790 Archived-At: On 10 July 2014 09:26, David Krauss wrote: >>> Assuming you mean * ( f().begin() ), I would expect that to be currently >>> broken, but the fix is to forbid begin() and end() on an xvalue because they >>> are fundamentally nonsense. It's a minor issue that some would-be ill-formed >>> code is currently accepted. >> >> >> These "fundamentally nonsense" operations work perfectly fine in forwarding >> scenarios. > > It's easy enough to bind an xvalue to a name throughout the scope it does not behave as an xvalue. I fail to see what sort of a solution that is supposed to provide. > Maybe I don't see exactly what you mean by "forwarding scenario," an example would be nice. The example is in this thread, as has been said multiple times already. https://groups.google.com/a/isocpp.org/d/msg/std-proposals/jDRQyBWYl8Q/iLJFlolCOBgJ We currently have ample reasons to change the rvalue-ref-qualified overloads of optional observers to return T&& instead of T. The summary, for those who don't read threads before jumping into them head first, is in https://issues.isocpp.org/show_bug.cgi?id=45 -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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