220 10096 article Path: news.gmane.org!not-for-mail From: Andrew Tomazos Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Shouldn't the constexpr variables be treated as static by default? Date: Sun, 30 Mar 2014 23:02:28 +0200 Lines: 148 Approved: news@gmane.org Message-ID: References: <21e34045-b833-4468-a39e-dbf177938012@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=047d7bf0c106a5ef8504f5d94076 X-Trace: ger.gmane.org 1396213355 30010 80.91.229.3 (30 Mar 2014 21:02:35 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 30 Mar 2014 21:02:35 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBD5KHQXXWYPRBZEM4KMQKGQEPCT5SGI@isocpp.org Sun Mar 30 23:02:30 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-bk0-f70.google.com ([209.85.214.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WUMs9-00005N-Q4 for gclcip-std-proposals@m.gmane.org; Sun, 30 Mar 2014 23:02:29 +0200 Original-Received: by mail-bk0-f70.google.com with SMTP id my13sf15399556bkb.9 for ; Sun, 30 Mar 2014 14:02:29 -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: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=zPC9OL4SeHx46miLYYEKLeG67AJoUnvWse38PgzsGRM=; b=Z78+b/06AOzP2UvhEkMJrzOadOBGrpzdb/9uCwaDCTk0u7md0xHjwktAaZG2WMHxSk 2bvgQtHhCFs9abRN6WGj1uWBBIHJ0Ph0ROdQ4jbYmolsKnrNCR/dUWZaKEczSSAu0aUz OmMBh2HR4D9BBAu2TYgH1+1fl8Fy2B26u/0QmQkGNNcF9yMj8CJV8EmFUhlqJvrKx7gN 9GmY+GTX4sBLrgNuI7Tfh8NMLr6XOPoTbncAFOTVAlRb0XsmEgN3blBg23pTJYgneweF oyFf4PyhToW5xRiYPJhEZzHRBfCjLrmZG+YuJ3XqCTo+i/U6AB0eB4B5H71Ts03KALKJ mXIg== X-Gm-Message-State: ALoCoQnQ7xVGdKY2SkPkOxsTNP0sL6O/lzYX3GT7YIngnvV28tsy3CRri9QZi6cGmEGQWxmOhNfZ X-Received: by 10.180.198.133 with SMTP id jc5mr4797295wic.4.1396213349363; Sun, 30 Mar 2014 14:02:29 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.212.4 with SMTP id ng4ls349077wic.45.gmail; Sun, 30 Mar 2014 14:02:28 -0700 (PDT) X-Received: by 10.180.126.38 with SMTP id mv6mr7458778wib.46.1396213348430; Sun, 30 Mar 2014 14:02:28 -0700 (PDT) Original-Received: from mail-we0-x232.google.com (mail-we0-x232.google.com [2a00:1450:400c:c03::232]) by mx.google.com with ESMTPS id jt9si2315944wjc.180.2014.03.30.14.02.28 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 30 Mar 2014 14:02:28 -0700 (PDT) Received-SPF: pass (google.com: domain of andrewtomazos@gmail.com designates 2a00:1450:400c:c03::232 as permitted sender) client-ip=2a00:1450:400c:c03::232; Original-Received: by mail-we0-f178.google.com with SMTP id u56so4047908wes.9 for ; Sun, 30 Mar 2014 14:02:28 -0700 (PDT) X-Received: by 10.194.82.35 with SMTP id f3mr9323955wjy.36.1396213348165; Sun, 30 Mar 2014 14:02:28 -0700 (PDT) Original-Received: by 10.227.147.134 with HTTP; Sun, 30 Mar 2014 14:02:28 -0700 (PDT) In-Reply-To: <21e34045-b833-4468-a39e-dbf177938012@isocpp.org> X-Original-Sender: andrewtomazos@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of andrewtomazos@gmail.com designates 2a00:1450:400c:c03::232 as permitted sender) smtp.mail=andrewtomazos@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:10096 Archived-At: --047d7bf0c106a5ef8504f5d94076 Content-Type: text/plain; charset=ISO-8859-1 This would be a breaking change: #include void f(int y) { if (y == 0) return; constexpr int x = 3; const int* p = &x; std::printf("%p\n", p); f(y-1); } int main() { f(3); } prints: 0x7fff125fdad8 0x7fff125fdaa8 0x7fff125fda78 whereas with static constexpr it prints: 0x400714 0x400714 0x400714 On Sun, Mar 30, 2014 at 10:55 PM, Mikhail Semenov < mikhailsemenov1957@gmail.com> wrote: > There is a recommendation to define all *constexpr* variables as static. > Shouldn't they be defined like that by default, meaning wherever we write > > *constexpr double x = 5.1;* > > the variable x will be assumed always to have *static storage duration*? > > > > > > > > -- > > --- > 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/. > -- --- 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/. --047d7bf0c106a5ef8504f5d94076 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
This would be a breaking change:

#= include <cstdio>

void f(int y)
{
=A0 =A0 =A0 =A0 if (y =3D=3D 0)
=A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 return;

=A0 =A0 =A0 =A0 constexpr int x =3D 3;
=A0 =A0 =A0 =A0= const int* p =3D &x;

=A0 =A0 =A0 =A0 std::pri= ntf("%p\n", p);

=A0 =A0 =A0 =A0 f(y-1);<= /div>
}

int main()
{
=A0 =A0 =A0 =A0 f(3);
}

prints:

0x7fff125= fdad8
0x7fff125fdaa8
0x7fff125fda78
whereas with static constexpr it prints:

0x400714
0x400714
0x400714

<= div>



On Sun, Mar 30, 2014 at 10:55 PM, Mikhail Semenov <mikhailsemen= ov1957@gmail.com> wrote:
There is a recommendation to define all const= expr variables as static.
Shouldn't they be defined= like that by default, meaning wherever we write

constexpr double x =3D 5.1;

the variable x will be assumed=A0 always to have =A0static storage= duration?






=

--

---
You received this message because you are subscribed to the Google Groups &= quot;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/gro= up/std-proposals/.

--

---
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+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/<= /a>.
--047d7bf0c106a5ef8504f5d94076-- .