220 29893 article Path: news.gmane.org!.POSTED!not-for-mail From: Manuel Bergler Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: New smart pointer: CopyConstructible and CopyAssignable flavor of unique_ptr Date: Sat, 17 Dec 2016 22:25:36 +0100 Lines: 72 Approved: news@gmane.org Message-ID: References: <3df7e8eb-01a0-7804-f476-504b5a25a9fe@gmail.com> <20161217170428.GA10214@manuel-ThinkPad-L440.localdomain> <20161217171633.4919375.58072.21574@gmail.com> <15884364-3238-41c7-bc5a-aa5595a64ade@isocpp.org> <20161217182130.GA4347@manuel-ThinkPad-L440.localdomain> <5eae5f16-e129-4c95-8001-fc73cc4f3d03@isocpp.org> <20161217192812.GA17421@manuel-ThinkPad-L440.localdomain> <20161217210804.GA10967@manuel-ThinkPad-L440.localdomain> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a114488a6daee590543e153c8 X-Trace: blaine.gmane.org 1482009940 16149 195.159.176.226 (17 Dec 2016 21:25:40 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 17 Dec 2016 21:25:40 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDOZBAUFX4MRBUO223BAKGQETKRP34I@isocpp.org Sat Dec 17 22:25:35 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pg0-f69.google.com ([74.125.83.69]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cIMU2-00035K-KX for gclcip-std-proposals@m.gmane.org; Sat, 17 Dec 2016 22:25:34 +0100 Original-Received: by mail-pg0-f69.google.com with SMTP id f188sf286946009pgc.1 for ; Sat, 17 Dec 2016 13:25:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=dAcVGRIc1uQ7p0vDk5/cBfVMnJy2LmMigsoVID3TVFI=; b=ehIQhcjRJfgTTz3T8N0jKADvsNsC18zNCV70qoHOnckHZGIG/u8w/xcSMmv95/3e7Y jpUYPjy0XzQubmEhhmld8MSNLqAuEA6TNiSTooHzOsFzggmSS1aUCN6huQYhYthpoSvP 7X0/C2Yggz1zPRvCvSK7qdXVbQp7IvXMJ+5QQZEl7wn2gUibE5TuiOw1mzmiGIS9PYRm SR5twzPhCrgInTV2TbjgpXaESQY6IepzIg5C8Bp9fSOZNxWQ54d8XHKTPVvKtmCbbldO +4jgC9SuEpxQAshlg4lDdHD6oR30fVNmBsoCZwiDjuEKKyOl9iOg7saeKUYNSKDIZ/X6 Dm1Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=dAcVGRIc1uQ7p0vDk5/cBfVMnJy2LmMigsoVID3TVFI=; b=C+XUJ1BD+ZWiN5Kr4Hfq1h96Q2YL3r9/yHyXEXZf+/O4Hy4PPAQnkSI03r4tWU32RI vQ+imVIFTsbbOa3qXbAmkM/VJJn06ziMJQZ/YkQ7gJqZxMfq0ZZ68zsHpXsd2EtraHA2 YAjXus23npSdkVgRqtuDWnpbrvRA1dq/TB38F4PBYWiWKC81189U8U9Eqv/RuGh1bMn0 xIxaeFCOe5UMr71eVhrSkEae1j8U2Gtt+Gar2+3QaQqQwFz0LdTkuAewv+lzmXg6Vavq JcpMhSOLUqcz/Cc+NPpdbdm5yHW38xzZvS3BeMelXcm/aO2rRZl0Y+QkB4xspIoPzgfk OTMQ== X-Gm-Message-State: AKaTC01ekaah1MAhYwipkTlMYdJvaiuoGX6LfEuZaWswaVUbx8v3jRBuJ+4DusRSEo1Pkg== X-Received: by 10.99.108.71 with SMTP id h68mr5294460pgc.23.1482009938743; Sat, 17 Dec 2016 13:25:38 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.11.41 with SMTP id v41ls3007227ioi.37.gmail; Sat, 17 Dec 2016 13:25:37 -0800 (PST) X-Received: by 10.36.71.208 with SMTP id t199mr3683829itb.112.1482009937483; Sat, 17 Dec 2016 13:25:37 -0800 (PST) Original-Received: from mail-it0-x22a.google.com (mail-it0-x22a.google.com. [2607:f8b0:4001:c0b::22a]) by mx.google.com with ESMTPS id n64si6505474itn.57.2016.12.17.13.25.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 17 Dec 2016 13:25:37 -0800 (PST) Received-SPF: pass (google.com: domain of berglerma@gmail.com designates 2607:f8b0:4001:c0b::22a as permitted sender) client-ip=2607:f8b0:4001:c0b::22a; Original-Received: by mail-it0-x22a.google.com with SMTP id b132so21000425iti.1 for ; Sat, 17 Dec 2016 13:25:37 -0800 (PST) X-Received: by 10.36.76.81 with SMTP id a78mr9277080itb.30.1482009937109; Sat, 17 Dec 2016 13:25:37 -0800 (PST) Original-Received: by 10.79.13.203 with HTTP; Sat, 17 Dec 2016 13:25:36 -0800 (PST) In-Reply-To: <20161217210804.GA10967@manuel-ThinkPad-L440.localdomain> X-Original-Sender: berglerma@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of berglerma@gmail.com designates 2607:f8b0:4001:c0b::22a as permitted sender) smtp.mailfrom=berglerma@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:29893 Archived-At: --001a114488a6daee590543e153c8 Content-Type: text/plain; charset=UTF-8 On Sat, Dec 17, 2016 at 10:08 PM, Manuel Bergler wrote: > Apparently clang and gcc interpret this differently: They move it into > place due to the std::move (see http://coliru.stacked-crooked. > com/a/cbe39ffef2ebf716). > > So in case of clang/gcc in my example the call to std::accumulate wouldn't > invalidate existing references. But who knows, maybe some implementer of > the standard library will interpret the requirements the same way you did > and actually perform a copy. But only forgetting to `return > std::move(acc);` in the lambda used for `std::accumulate` and using just > `return acc;` results in a copy. > I just tested it with msvc (http://rextester.com/SZRHBC97716), as a matter of fact they do indeed perform the copy as you suggested. So you end up with platform dependent behavior for this one... -- 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/CAM76qmtM9vxhmiCSaFLSm5Toct3qQ07wpPZU%3DbJa_v6H9BQbjQ%40mail.gmail.com. --001a114488a6daee590543e153c8 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On S= at, Dec 17, 2016 at 10:08 PM, Manuel Bergler <berglerma@gmail.com&g= t; wrote:
Apparently clang and gcc interpret this differently: They move it into plac= e due to the std::move (see http://coliru.stacke= d-crooked.com/a/cbe39ffef2ebf716).

So in case of clang/gcc in my example the call to std::accumulate wouldn= 9;t invalidate existing references. But who knows, maybe some implementer o= f the standard library will interpret the requirements the same way you did= and actually perform a copy. But only forgetting to `return std::move(acc)= ;` in the lambda used for `std::accumulate` and using just `return acc;` re= sults in a copy.

I just tested it with = msvc (http://rextester.com/SZR= HBC97716), as a matter of fact they do indeed perform the copy as you s= uggested. So you end up with platform dependent behavior for this one...

--
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