220 11756 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: Wed, 9 Jul 2014 23:11:10 +0300 Lines: 23 Approved: news@gmane.org Message-ID: References: <2555993.7LIlHKVULI@tjmaciei-mobl4> 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 1404936682 28829 80.91.229.3 (9 Jul 2014 20:11:22 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 9 Jul 2014 20:11:22 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5JHI7A7ALRBX6D62OQKGQEULP3EQQ@isocpp.org Wed Jul 09 22:11:16 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yk0-f198.google.com ([209.85.160.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1X4yCu-0003C5-O9 for gclcip-std-proposals@m.gmane.org; Wed, 09 Jul 2014 22:11:12 +0200 Original-Received: by mail-yk0-f198.google.com with SMTP id 9sf18326328ykp.9 for ; Wed, 09 Jul 2014 13:11:11 -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=6DvbJJ57wiVzyHJRxMNWzPt++8Fwsy7s6E8UoVB0P9w=; b=ehVh0zZHqMwQ0A7XkYK21N+S//EQRO8QPLvZgbL+AooU3a+MYe2S7ujYQKIv7RF4gh 7NYVUQ7dgwD9U+FfBXROUoiEasbkBtusbUibtw0PFDQXqSKvR5/qRpn/rJmMDL6dSh5a zPuPNn82ltvC1FfNv8HzFv/GiVSfi2LCpjkKgZ5n3Ic12cKx4lLhC7z2GlYHQwjph89N doO19wCmqpMV6iX6JOaB+7H4huklm1KEkKqHBbSkB6IKKjOU6J+iTTQjILkUmVhIWV0m BL31dYZxt/NO+WBmAHgHx6lyzkyWs/IN3GQ5Yq45W8aTMy14FRzH6RCkLtf1Tq0Tjl/3 uapQ== X-Gm-Message-State: ALoCoQnMaQ+6PmM38qw8dnyY1d1t3cBl8vGDLFE6mmiCaoUosxgoA0LNfhX83kPsDVufhVfAM2Y+ X-Received: by 10.224.171.130 with SMTP id h2mr20810289qaz.7.1404936671765; Wed, 09 Jul 2014 13:11:11 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.98.225 with SMTP id o88ls4577qge.88.gmail; Wed, 09 Jul 2014 13:11:11 -0700 (PDT) X-Received: by 10.58.56.102 with SMTP id z6mr40424987vep.7.1404936671097; Wed, 09 Jul 2014 13:11:11 -0700 (PDT) Original-Received: from mail-vc0-x22e.google.com (mail-vc0-x22e.google.com [2607:f8b0:400c:c03::22e]) by mx.google.com with ESMTPS id 16si21991273vdd.92.2014.07.09.13.11.11 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 09 Jul 2014 13:11:11 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400c:c03::22e as permitted sender) client-ip=2607:f8b0:400c:c03::22e; Original-Received: by mail-vc0-f174.google.com with SMTP id hy4so8214980vcb.5 for ; Wed, 09 Jul 2014 13:11:11 -0700 (PDT) X-Received: by 10.220.44.20 with SMTP id y20mr2231202vce.60.1404936671029; Wed, 09 Jul 2014 13:11:11 -0700 (PDT) Original-Received: by 10.224.31.137 with HTTP; Wed, 9 Jul 2014 13:11:10 -0700 (PDT) In-Reply-To: <2555993.7LIlHKVULI@tjmaciei-mobl4> 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:f8b0:400c:c03::22e 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:11756 Archived-At: On 9 July 2014 23:03, Thiago Macieira wrote: > On Wednesday 09 July 2014 12:09:14 'Jeffrey Yasskin' via ISO C++ Standard - > Future Proposals wrote: >> std::pair g(); >> auto&& s = g().first; //will create a dangling reference > > If you were to use auto or decltype(auto), the problem would go away, wouldn't > it? Some problems would, but some problems wouldn't. You may have an lvalue optional and you don't want to get a copy of the underlying value in that case. decltype(auto) will not help if the function returns an rvalue reference, since that would be the type of decltype(auto), too, right? -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. .