220 4876 article Path: news.gmane.org!not-for-mail From: Zhihao Yuan Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Proposal: std::sequence Date: Tue, 4 Jun 2013 21:23:55 -0400 Lines: 39 Approved: news@gmane.org Message-ID: References: <4551abbc-43aa-4520-a91a-f8eb25a90588@isocpp.org> <2c8e6079-9c87-425a-93e2-39251df57cd8@isocpp.org> <9f1cace3-0503-4a3c-a8ce-d7546564b3ef@isocpp.org> <1c991e6e-6bc3-4822-9ffd-7f2508e63974@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: ger.gmane.org 1370395436 21450 80.91.229.3 (5 Jun 2013 01:23:56 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 5 Jun 2013 01:23:56 +0000 (UTC) To: "std-proposals@isocpp.org" Original-X-From: std-proposals+bncBCUILMGRQMARBLFGXKGQKGQE2WFIC7I@isocpp.org Wed Jun 05 03:23:57 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wg0-f69.google.com ([74.125.82.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Uk2SD-0006U3-35 for gclcip-std-proposals@m.gmane.org; Wed, 05 Jun 2013 03:23:57 +0200 Original-Received: by mail-wg0-f69.google.com with SMTP id j13sf884905wgh.0 for ; Tue, 04 Jun 2013 18:23:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-beenthere: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:x-google-group-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe :content-type; bh=Pbl78lTxzBkS9nALpgPT6gtntLFL3r5CX9jBeFmf+PQ=; b=s6hsBOSuT3zS5dooNGqk0oO67OP9S0qQpcXj05cfZrOovvTepmGx+8+5qC4X3dNSwJ 3joVcIybBwSPfPgVyAt2wPZg4KCA2aW/EZPKh55U2hcGAh5+kvxpP2xrQexQ+22z4zio D9YtX7BUt6OR+bHpwr9uQl6edbu9brzFzAen8o9yHqxitQ0B3gXQT1qzYv7EhXsfpIs7 c8qMooCssYh1z48Ps2pfpYN2QrgtGgwEhv5A1lSjZTtCR8Acs3rd4u54YIwxITQOg4+H AJlMWDy1o0t5dNCvqLK0rdjO82K6VCOOqn2LLliYyJF59jIX5LLOT1dt9b8+wrF4su8P yERA== X-Received: by 10.112.74.82 with SMTP id r18mr4536591lbv.4.1370395436745; Tue, 04 Jun 2013 18:23:56 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.152.43.198 with SMTP id y6ls33919lal.38.gmail; Tue, 04 Jun 2013 18:23:55 -0700 (PDT) X-Received: by 10.112.60.8 with SMTP id d8mr14079426lbr.39.1370395435800; Tue, 04 Jun 2013 18:23:55 -0700 (PDT) Original-Received: from mail-la0-x229.google.com (mail-la0-x229.google.com [2a00:1450:4010:c03::229]) by mx.google.com with ESMTPS id lj8si18016994lab.124.2013.06.04.18.23.55 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 04 Jun 2013 18:23:55 -0700 (PDT) Received-SPF: pass (google.com: domain of lichray@gmail.com designates 2a00:1450:4010:c03::229 as permitted sender) client-ip=2a00:1450:4010:c03::229; Original-Received: by mail-la0-f41.google.com with SMTP id fn20so898284lab.14 for ; Tue, 04 Jun 2013 18:23:55 -0700 (PDT) X-Received: by 10.112.60.195 with SMTP id j3mr13786123lbr.37.1370395435618; Tue, 04 Jun 2013 18:23:55 -0700 (PDT) Original-Received: by 10.112.146.99 with HTTP; Tue, 4 Jun 2013 18:23:55 -0700 (PDT) In-Reply-To: X-Original-Sender: lichray@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of lichray@gmail.com designates 2a00:1450:4010:c03::229 as permitted sender) smtp.mail=lichray@gmail.com; dkim=pass header.i=@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:4876 Archived-At: On Tue, Jun 4, 2013 at 9:11 PM, Nevin Liber wrote: > On 4 June 2013 20:06, Zhihao Yuan wrote: >> >> int main() { >> A a; >> f((int*)&a); >> std::cout << a.x; >> } >> >> Then you will find that the 'optimization' no longer works. >> > > You are invoking undefined behavior, so whether or not the optimization > works in this case is irrelevant. Oh, typo, sorry. You mean strict aliasing. Should be A a; f((int*)&a.x); std::cout << a.x; -- Zhihao Yuan, ID lichray The best way to predict the future is to invent it. ___________________________________________________ 4BSD -- http://4bsd.biz/ -- --- 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/?hl=en. .