220 9821 article Path: news.gmane.org!not-for-mail From: Andrew Tomazos Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: auto variable templates? Date: Sat, 15 Mar 2014 13:46:21 -0700 (PDT) Lines: 132 Approved: news@gmane.org Message-ID: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_275_17891816.1394916381800" X-Trace: ger.gmane.org 1394916377 8305 80.91.229.3 (15 Mar 2014 20:46:17 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 15 Mar 2014 20:46:17 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBD5KHQXXWYPRBHXYSKMQKGQE62BGQ7Q@isocpp.org Sat Mar 15 21:46:27 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ve0-f198.google.com ([209.85.128.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WOvTM-0004wZ-R3 for gclcip-std-proposals@m.gmane.org; Sat, 15 Mar 2014 21:46:25 +0100 Original-Received: by mail-ve0-f198.google.com with SMTP id oz11sf9554983veb.9 for ; Sat, 15 Mar 2014 13:46:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe:content-type; bh=XA9kUUD4EShM1yr2ROrhUu21dRI8j1f1p1areA0qVqo=; b=l6wpLhaaaMRzEpObZtqFZKfnXywjkNEHV6sBSi8d7gEunwiRXpoUxRxvppH820yt1l cqMoVacflPqd7p5abiF8CZpBCps6wCPYoVfsgnU/CCDuHsnHBwJOxcv80PSQHzMLwd6F Kkt4XyMzx/z4BqFWk0ddNU3DbS5l8DPhMwQLmcjnBrqjHwXbZg/Y/sHR82/dKWcwqg0M 2S6gTAZbUlVaF26ctZlDn5xZrzX3Nv0RkIdxTMsUVLZ/ZCPkVZzNasRzVzfEZEzLU9+7 IBqh/eSDe5WrvEJl9Ie8+NPBxTgi9jZk0VKw8npIOADC/PMW35W2g3sZ7elVYOC/hQl/ dNgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:message-id:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe :content-type; bh=XA9kUUD4EShM1yr2ROrhUu21dRI8j1f1p1areA0qVqo=; b=ONjNz3RE/WETnvq4AtbQhF32DEirdg6rJ9Hc3gFdA5IjGB6PFsRTZ+iVR+RecW3VCE ig5fWyRGM0qMfhXYI06yACJ/bik+Ui28hoTaoQknxNIpVLegsXJfZS0xH6h3kdXcTKMT YJh+Cg3QOoEEZvK2FMyLkVdKZthKrsjImoDqMCuy4HD5vPJKxKpXGYKaPFUBucnZAnPD 2Xd7ma9WIaY1dZ4Oa4+xnrbPzzhXtR0UESWiX6e2wOD1zkxCyna0zy6C03vqr12VxAgC dVcui8MvOeIQ4cCEdeAxIF95T3VFCOTLMpXgr8iENWlQsmb6Of66QUGG+8JWiZmMeVsK TKvQ== X-Gm-Message-State: ALoCoQmztD19z1abA/e7M2XToO+a5uraWrildoJCvds6GQFZO8XHvsyXZBIYvlkMZdgtkh9EqST6 X-Received: by 10.236.125.6 with SMTP id y6mr5523526yhh.3.1394916383415; Sat, 15 Mar 2014 13:46:23 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.107.7 with SMTP id g7ls1197466qgf.53.gmail; Sat, 15 Mar 2014 13:46:22 -0700 (PDT) X-Received: by 10.140.108.6 with SMTP id i6mr293568qgf.0.1394916382563; Sat, 15 Mar 2014 13:46:22 -0700 (PDT) X-Original-Sender: andrewtomazos@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:9821 Archived-At: ------=_Part_275_17891816.1394916381800 Content-Type: text/plain; charset=UTF-8 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. Clang trunk rejects it, albeit it with an obtuse error message: "invalid operands to binary expression ('auto' and 'int')" Was this intended? If so, what was the problem with having them? auto variable templates would be very useful. -- --- 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/. ------=_Part_275_17891816.1394916381800 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Is the following supposed to be ill-formed according to th= e current draft?

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

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

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

Clang trunk rejects it, albeit it with an obtuse error message: "invalid operands to binary expression ('au= to' and 'int')"

Was this intended?

If so, what was= the problem with having them?  auto variable templates would be very = useful.

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