220 9822 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 16:38:44 -0700 Lines: 137 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=001a11c1d71ce9ba4a04f4adaf8d X-Trace: ger.gmane.org 1394926718 12387 80.91.229.3 (15 Mar 2014 23:38:38 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 15 Mar 2014 23:38:38 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDVNBJG4YAIBBBOJSOMQKGQEKFC3IZQ@isocpp.org Sun Mar 16 00:38:48 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qa0-f72.google.com ([209.85.216.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WOyAA-0001tN-Of for gclcip-std-proposals@m.gmane.org; Sun, 16 Mar 2014 00:38:47 +0100 Original-Received: by mail-qa0-f72.google.com with SMTP id f11sf8548071qae.11 for ; Sat, 15 Mar 2014 16:38:45 -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=revwD4OCHnZCw+5Y0uSJK2QW+QJeHaQeKIA2wMiWpjE=; b=EvTe3RAP3M2j6nUB7edHVQi5p8YHiT/ZA9D1fwhPrzFzAC7Kmfkm8rhnhMxie/j5Tw hz3SevSsfw1WNnXhKsIxfWLwZVES/mVtms1aDrcjEgNocIluDY91zs1vHOMde2NDEZ9N swWD7KY8xSbQD6YEdvpM4sbzRvdJQlOP2zq8r/FiImNk/KlKTtzOr8jYVCroRuHZgaoS 3QLgepLP4nwAJ0duKauhiL4c3TlNx5ckdYqugTUBwt6RW4RcI8jtl66iTokTgt11OfeT X3j+xIsc2E6wcGJqhmu7anAjAZ7G+EJkHS8ohfaPXPWMAqND//9dv4cPvbwaOjBqP52V fl8g== X-Gm-Message-State: ALoCoQk3TMQ+FuqjMQt0sjL58fzSQ3Lk+yXUW70DnzoLa06pPgtIfpGjFifffuIG/SIo5wr9dUy+ X-Received: by 10.236.96.138 with SMTP id r10mr4862602yhf.12.1394926725853; Sat, 15 Mar 2014 16:38:45 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.82.39 with SMTP id g36ls1140136qgd.25.gmail; Sat, 15 Mar 2014 16:38:45 -0700 (PDT) X-Received: by 10.221.29.137 with SMTP id ry9mr13089742vcb.6.1394926725013; Sat, 15 Mar 2014 16:38:45 -0700 (PDT) Original-Received: from mail-vc0-x22b.google.com (mail-vc0-x22b.google.com [2607:f8b0:400c:c03::22b]) by mx.google.com with ESMTPS id uh1si3686493vcb.100.2014.03.15.16.38.44 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 15 Mar 2014 16:38:44 -0700 (PDT) Received-SPF: pass (google.com: domain of metafoo@gmail.com designates 2607:f8b0:400c:c03::22b as permitted sender) client-ip=2607:f8b0:400c:c03::22b; Original-Received: by mail-vc0-f171.google.com with SMTP id lg15so4259773vcb.2 for ; Sat, 15 Mar 2014 16:38:44 -0700 (PDT) X-Received: by 10.220.99.72 with SMTP id t8mr13111358vcn.10.1394926724690; Sat, 15 Mar 2014 16:38:44 -0700 (PDT) Original-Sender: metafoo@gmail.com Original-Received: by 10.58.218.131 with HTTP; Sat, 15 Mar 2014 16:38:44 -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::22b 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:9822 Archived-At: --001a11c1d71ce9ba4a04f4adaf8d Content-Type: text/plain; charset=ISO-8859-1 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. -- --- 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/. --001a11c1d71ce9ba4a04f4adaf8d Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
On S= at, Mar 15, 2014 at 1:46 PM, Andrew Tomazos <andrewtomazos@gmail.c= om> 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 templ= ate is a variable, so this is allowed.
=A0
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.

--

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