220 9831 <93E854CB-24C9-49ED-BE88-1A43D0FD715A@gmail.com> article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: auto variable templates? Date: Sun, 16 Mar 2014 16:00:02 +0800 Lines: 79 Approved: news@gmane.org Message-ID: <93E854CB-24C9-49ED-BE88-1A43D0FD715A@gmail.com> References: <878usaa8hz.fsf@euclid.axiomatics.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 7.2 \(1874\)) Content-Type: multipart/alternative; boundary="Apple-Mail=_1F6E5604-0410-4CF4-BB7A-1C6308A8C33F" X-Trace: ger.gmane.org 1394956803 26212 80.91.229.3 (16 Mar 2014 08:00:03 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 16 Mar 2014 08:00:03 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBB5USWMQKGQE7GY6V7Q@isocpp.org Sun Mar 16 09:00:12 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ig0-f199.google.com ([209.85.213.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WP5zN-0008EV-QN for gclcip-std-proposals@m.gmane.org; Sun, 16 Mar 2014 09:00:10 +0100 Original-Received: by mail-ig0-f199.google.com with SMTP id uy17sf5014066igb.2 for ; Sun, 16 Mar 2014 01:00:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:message-id:mime-version:subject:date :references:to:in-reply-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=1uz7BR78zu8yKP/nltIWk0BkQsJiSoCsPaor9pWTQSE=; b=QwEl2bbXidMMGllcl2AjOpQSzOawvHuqpvEHoSOC45XiaILwHwSw9AitXuP45dPCR8 LrKJe+T/Scm6jot9NRt6Lo3TTzYLGXffcfKeovq4APczwpwbv8nywYFWMLUwyb/j59y2 yZvz2q1xas9BheMJ0QYerF300lnu7jagzZawTd1REUSW45cNb8JtdDs4j9h8Q21w/fKE gT6ISMroAjFjGe0q/appYgToEE1qqs/pPoQ870iLjRTWtw/6ByrEB9MT0+DoA6CKmqFk 7vZXklrikiOWt4yPHQqePy8iLUgKE5kIhZREmJCiyat73jTUq212b9Nk9k7pRdNHi2UO P3ZQ== X-Gm-Message-State: ALoCoQmlqDAKzS2Yxh4CaE5ajCq8FvGpekOsRWq5vyL8wYmphSvvGvE7UAeFYGPtAWds3LFXhtVs X-Received: by 10.50.114.134 with SMTP id jg6mr2935210igb.2.1394956808516; Sun, 16 Mar 2014 01:00:08 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.111.135 with SMTP id ii7ls576713igb.30.canary; Sun, 16 Mar 2014 01:00:07 -0700 (PDT) X-Received: by 10.69.31.75 with SMTP id kk11mr18609790pbd.101.1394956807309; Sun, 16 Mar 2014 01:00:07 -0700 (PDT) Original-Received: from mail-pb0-x22f.google.com (mail-pb0-x22f.google.com [2607:f8b0:400e:c01::22f]) by mx.google.com with ESMTPS id iw3si2632573pac.383.2014.03.16.01.00.07 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 16 Mar 2014 01:00:07 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c01::22f as permitted sender) client-ip=2607:f8b0:400e:c01::22f; Original-Received: by mail-pb0-f47.google.com with SMTP id up15so4413081pbc.20 for ; Sun, 16 Mar 2014 01:00:07 -0700 (PDT) X-Received: by 10.66.141.197 with SMTP id rq5mr19255620pab.64.1394956807212; Sun, 16 Mar 2014 01:00:07 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.54.54]) by mx.google.com with ESMTPSA id tu3sm53089514pab.1.2014.03.16.01.00.05 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 16 Mar 2014 01:00:06 -0700 (PDT) In-Reply-To: <878usaa8hz.fsf@euclid.axiomatics.org> X-Mailer: Apple Mail (2.1874) X-Original-Sender: potswa@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c01::22f as permitted sender) smtp.mail=potswa@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:9831 Archived-At: --Apple-Mail=_1F6E5604-0410-4CF4-BB7A-1C6308A8C33F Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=ISO-8859-1 On 2014-03-16, at 3:49 PM, Gabriel Dos Reis wrote: > The general model of C++ templates, since day 1, is that if decl is a > valid declaration, then >=20 > template decl >=20 > is also a valid declaration. Well, Johannes' code is specifically a counterexample to that rule, because= the error is in the parameter-list. It seems fairly obvious that an invalid template parameter declaration is d= iagnosed when translating it, not at instantiation. If his code exposes a d= efect, it belongs to name lookup, not the instantiation process. (Should th= at name be accessible, if the template had a friend declaration? However it= is not a friend in the example.) His argument, though, seems to be that there is a slippery slope of allowin= g things that aren't specifically specified. I don't buy it. --=20 ---=20 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 e= mail 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-proposa= ls/. --Apple-Mail=_1F6E5604-0410-4CF4-BB7A-1C6308A8C33F Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1
On 2014&= ndash;03–16, at 3:49 PM, Gabriel Dos Reis <gdr@axiomatics.org> wrote:

The general model of C++ templ= ates, since day 1, is that if decl is a
valid declaration, then

=   template <parameter-list> decl

is also a valid dec= laration.

Well, Johannes’ code is spe= cifically a counterexample to that rule, because the error is in the parame= ter-list.

It seems fairly obvious that an invalid = template parameter declaration is diagnosed when translating it, not at ins= tantiation. If his code exposes a defect, it belongs to name lookup, not th= e instantiation process. (Should that name be accessible, if th= e template had a friend declaration? However = it is not a friend in the example.)

His argument, though, seems to be that there is a sli= ppery slope of allowing things that aren’t specifically specified. I = don’t buy it.

--

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