220 9827 article Path: news.gmane.org!not-for-mail From: Richard Smith Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: auto variable templates? Date: Sat, 15 Mar 2014 18:07:34 -0700 Lines: 153 Approved: news@gmane.org Message-ID: References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a11c2ca0c9fcc5104f4aeed98 X-Trace: ger.gmane.org 1394932049 5001 80.91.229.3 (16 Mar 2014 01:07:29 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 16 Mar 2014 01:07:29 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDVNBJG4YAIBBV7SSOMQKGQENBJ3DQI@isocpp.org Sun Mar 16 02:07:39 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pa0-f72.google.com ([209.85.220.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WOzY9-0003ei-Cs for gclcip-std-proposals@m.gmane.org; Sun, 16 Mar 2014 02:07:37 +0100 Original-Received: by mail-pa0-f72.google.com with SMTP id bj1sf10383645pad.11 for ; Sat, 15 Mar 2014 18:07:36 -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:sender: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=ZJE5DiyC+WbB4CU/ncMVKcrQ5jSCSpNUzgAt6i4rHzI=; b=KikXKHMZ3Mi6KxnEgjEkjXWTPArh1/RVpQYWjfghReTUXddN/O7TunKQvBHQg69oZ7 BbqIl5NpTt4CIHdqIdogr6DJzP75enxxSAAikDPZcIBXXYOD74IQYjL4Bpe8lqZHfgUM Tu3J/yuhSShWwU95w/IoCf32BiM35krnyNiEXpHyE7NLKR84FiTGISKPS7RDMMpFaGrQ EyOZNN9PBMKvmzbVXM3qcLUr6/3NnAx2OKkzPUAI+aqoEMhmI/USmTN0mr5yAXmrZPZV gtIKpiU167I3J3egTgxl2uJYo6Q3gM3MK15JpsOUW+M/M4h/Eo6oT2/gVWXL2702gNuh lCvA== X-Gm-Message-State: ALoCoQkL+E7L73Xr5Q6S/0Ucd4A1mBobx9Bb10Fb1SbOSYElRM33FkGPh527CJIQlDwM/6ae/mPA X-Received: by 10.66.231.132 with SMTP id tg4mr6289645pac.31.1394932056107; Sat, 15 Mar 2014 18:07:36 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.88.101 with SMTP id s92ls1197484qgd.82.gmail; Sat, 15 Mar 2014 18:07:35 -0700 (PDT) X-Received: by 10.52.251.199 with SMTP id zm7mr11307539vdc.21.1394932055133; Sat, 15 Mar 2014 18:07:35 -0700 (PDT) Original-Received: from mail-vc0-x22d.google.com (mail-vc0-x22d.google.com [2607:f8b0:400c:c03::22d]) by mx.google.com with ESMTPS id xb4si667942vdc.192.2014.03.15.18.07.35 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 15 Mar 2014 18:07:35 -0700 (PDT) Received-SPF: pass (google.com: domain of metafoo@gmail.com designates 2607:f8b0:400c:c03::22d as permitted sender) client-ip=2607:f8b0:400c:c03::22d; Original-Received: by mail-vc0-f173.google.com with SMTP id il7so4436408vcb.32 for ; Sat, 15 Mar 2014 18:07:35 -0700 (PDT) X-Received: by 10.220.159.4 with SMTP id h4mr2088202vcx.1.1394932055000; Sat, 15 Mar 2014 18:07:35 -0700 (PDT) Original-Sender: metafoo@gmail.com Original-Received: by 10.58.218.131 with HTTP; Sat, 15 Mar 2014 18:07:34 -0700 (PDT) In-Reply-To: X-Original-Sender: richard@metafoo.co.uk X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of metafoo@gmail.com designates 2607:f8b0:400c:c03::22d as permitted sender) smtp.mail=metafoo@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:9827 Archived-At: --001a11c2ca0c9fcc5104f4aeed98 Content-Type: text/plain; charset=ISO-8859-1 On Sat, Mar 15, 2014 at 4:38 PM, Richard Smith wrote: > On Sat, Mar 15, 2014 at 1:46 PM, Andrew Tomazos wrote: > >> Is the following supposed to be ill-formed according to the current draft? >> >> template constexpr auto X = 42; >> int main(){ >> static_assert(X == 42, "");} >> >> >> [dcl.spec.auto]/4 says that auto is allowed when declaring variables in >> namespace-scope, but doesn't explicitly say in variable templates - >> consequently this is ill-formed. >> > > A specialization of a variable template is a variable, so this is allowed. > > >> Clang trunk rejects it, albeit it with an obtuse error message: "invalid >> operands to binary expression ('auto' and 'int')" >> >> Was this intended? >> > > Looks like a bug. > (Now fixed in Clang trunk.) -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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On S= at, Mar 15, 2014 at 4:38 PM, Richard Smith <richard@metafoo.co.uk&= gt; wrote:
=
On Sat, Mar 15, 2014 at 1:46 PM,= Andrew Tomazos <andrewtomazos@gmail.com> wrote:
Is the following supposed t= o be ill-formed according to the current draft?

template<class> constexpr auto X =
=3D 42;

int main()
{
        st=
atic_assert(X<int> =3D=3D 42,=
 "");
}

[dcl.spec.auto]/4 says that auto is allowed when declarin= g variables in namespace-scope, but doesn't explicitly say in variable = templates - consequently this is ill-formed.

A specialization of a variable= template is a variable, so this is allowed.
=A0<= /div>
Clang trunk rejects it, albeit it with an obtuse erro= r message: "invalid operands to binary expression ('auto&= #39; and 'int')"

Was this intended?

Looks like a bug.

(Now fixed in Clang= trunk.)

--

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