220 37558 <9a9a7837-a014-4893-b0a0-75571921b3a3@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Edward Catmur Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Allowing std::complex's magic permission for other types Date: Thu, 29 Mar 2018 08:35:16 -0700 (PDT) Lines: 87 Approved: news@gmane.org Message-ID: <9a9a7837-a014-4893-b0a0-75571921b3a3@isocpp.org> References: <018c02d9-7c65-4451-acc1-c49196fc7622@isocpp.org> <1e25a8ae-4752-4fc0-8c89-639cef53121c@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_3023_132653232.1522337716286" X-Trace: blaine.gmane.org 1522337595 23493 195.159.176.226 (29 Mar 2018 15:33:15 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 29 Mar 2018 15:33:15 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDZLZTXF7UJBBNMP6TKQKGQERKQAU3I@isocpp.org Thu Mar 29 17:33:11 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f200.google.com ([209.85.217.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1f1ZY7-00061J-2H for gclcip-std-proposals@m.gmane.org; Thu, 29 Mar 2018 17:33:11 +0200 Original-Received: by mail-ua0-f200.google.com with SMTP id y5sf4093216uaa.15 for ; Thu, 29 Mar 2018 08:35:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=dVhdeH7Y5WW1UpSy9mo6j5iDpHabw5uBXKlTNRLDdUs=; b=vBj5/6Dn+dU5JTB47DUVDeMzV5Y7JHelnpKsszMJsi+aqmiKA0RSw2PQfGh9/0svEb iITFVlFUCTm79wCJHAuqV0HkwS6+tkWYY/4tXmr+JA4cJXzv3Z+yf0kJ8WHJ8yS0axrq dx4jSA6T/KwITXy4TVtNXOegj97BEfxyJQTVEFbd2eY57ruiVfS38DBaBKJv/R9CnHWa /WgMwxfo0jRMDY1a0mC2fDc0P2gQcw+RwKoliWhsMda9+2kAQt6+AUAUdTMxbm9aqXmJ zZnR9CPUy4m4tNnF7bNddQk9kDbMxj+/1BeJoGi7MJVZ2wMDAYCbPoy86raO6dJmjhh1 Nj6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=dVhdeH7Y5WW1UpSy9mo6j5iDpHabw5uBXKlTNRLDdUs=; b=FqgENA5L6JToIkAoofxylnm/Z66xoAoTTFsZ4zvxLW4vs6A1aYH/33TkyRSwJiNIOs dNOFwN+y5ZUtQge16dEM6ceqtjOH5cfz/6BBD9sz6mHG9tvkl7olaqSqvaXnpPBfhXAV g5jD9hp7YorNrLDzLUCKxgt/JgyltVEJupG2lQcG64IcLgVR5YbyQzd790vc4wxNxs4K oxPMGJjh/nSEaI67KfBmYC+bnQSYzpEwJpNiRUP59q5fIt1kSSjQtib18i8r0ZG+CLLk 1JTshtDkkXLXUyAnU9IkiegRy5kn4uKdo5qycnguydnXrOb+efswAxm+WA76Orpy+uxs 2EtQ== X-Gm-Message-State: AElRT7E6M23l+umoRskMod8UOOKnRXpCatnG9+APPzQq9F1JGLTMx6SH yqCEuP0t2b25ABv60ETUVE/b7w== X-Google-Smtp-Source: AG47ELsMNGLuS1HGS19CqGSeQscWYI2Vk5g3C9ldtjZwa98SFBcJ9c0pC42bSWg4C6lE9el0r9uW2Q== X-Received: by 10.176.73.194 with SMTP id f2mr22476107uad.122.1522337718518; Thu, 29 Mar 2018 08:35:18 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.208.1 with SMTP id h1ls3825324vkg.19.gmail; Thu, 29 Mar 2018 08:35:17 -0700 (PDT) X-Received: by 10.31.32.148 with SMTP id g142mr1805693vkg.1.1522337716774; Thu, 29 Mar 2018 08:35:16 -0700 (PDT) In-Reply-To: X-Original-Sender: ed@catmur.co.uk Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:37558 Archived-At: ------=_Part_3023_132653232.1522337716286 Content-Type: multipart/alternative; boundary="----=_Part_3024_140286881.1522337716286" ------=_Part_3024_140286881.1522337716286 Content-Type: text/plain; charset="UTF-8" On Thursday, 29 March 2018 07:17:27 UTC+1, Viacheslav Usov wrote: > > On Wed, Mar 28, 2018 at 6:38 PM, 'Edward Catmur' via ISO C++ Standard - > Future Proposals > wrote: > > > That's [expr.eq]/2.2, which comes after 2.1 and is guarded by an > "Otherwise". > > Per 2.2., "they compare equal" and your prior statements of unspecified > comparison are non sequitur. > > So, now, we have pointers to int (bar + 2) and baz representing the same > address and comparing equal, and baz[0] is well defined. > > What do you say about bar[2]? > I think it's reasonably clear that bar[2] is UB, even though bar + 2 compares equal to baz and baz[0] is well defined. See [basic.compound]/3. > Cheers, > V. > -- 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/9a9a7837-a014-4893-b0a0-75571921b3a3%40isocpp.org. ------=_Part_3024_140286881.1522337716286 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Thursday, 29 March 2018 07:17:27 UTC+1, Viaches= lav Usov wrote:
On Wed, Mar 28, 2018 at 6:38 PM, 'Ed= ward Catmur' via ISO C++ Standard - Future Proposals = <s= td-pr...@isocpp.org> wrote:

> That&= #39;s [expr.eq]/2.2, which comes after 2.1 and is guarded by an "Other= wise".

Per 2.2., "they compare equal&quo= t; and your prior statements of unspecified comparison are non sequitur.

So, now, we have pointers to int (bar + 2) and baz r= epresenting the same address and comparing equal, and baz[0] is well define= d.

What do you say about bar[2]?
=

I think it's reasonably clear th= at bar[2] is UB, even though bar + 2 compares equal to baz and baz[0] is we= ll defined. See [basic.compound]/3.


Cheers,
V.

--
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