220 15640 article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Library support for relaxed constexpr Date: Wed, 14 Jan 2015 06:01:43 +0800 Lines: 86 Approved: news@gmane.org Message-ID: References: <5ccd3d6e-859c-4b66-b61c-317b704647f2@isocpp.org> <14072581.09eDfPqFOs@tjmaciei-mobl4> <9F9D7F25-F862-4358-B074-8F8C87255E2A@gmail.com> <1c00c8fd-140a-42f6-b73a-628cbde1737b@isocpp.org> <0098656E-0F82-4B50-A59A-F55630245AB5@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 8.1 \(1993\)) Content-Type: multipart/alternative; boundary="Apple-Mail=_C9E71FB9-BB27-4A12-9767-829B1EBBEF62" X-Trace: ger.gmane.org 1421186518 20094 80.91.229.3 (13 Jan 2015 22:01:58 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 13 Jan 2015 22:01:58 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBTVL22SQKGQEAIPXEPI@isocpp.org Tue Jan 13 23:01:52 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qg0-f71.google.com ([209.85.192.71]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YB9X6-0008K5-5P for gclcip-std-proposals@m.gmane.org; Tue, 13 Jan 2015 23:01:52 +0100 Original-Received: by mail-qg0-f71.google.com with SMTP id z107sf13007869qgd.2 for ; Tue, 13 Jan 2015 14:01:50 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:content-type: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; bh=ufwgle4cZEqMRZIT4RfyCgDWqVdTRAo6ZMoIUIM+mdU=; b=GEqxRYyVmZc6cOGHYVngGpjtGmeDXPB/PP6uAyffNwV35Q+y43EJDEtPld7Q3b5sOu tMts3qh2aLV6H0sC5W935LOseoAxI+2QiqDUBfYCLzrKcfAAh3nE0QU8wSdn20xaXGgS 5MDi/ll0auAdASOKEKicrmb1EVVaoOjN6pxjhF2Wdnl11JocAMUFva/8CRePYG1oLKZp UwQZ3E78Y3vLPyW9TQR/oFVTSmhHJ26rl+5uX+GWv2H/pdBb05mMFgJTfTFqExFMeYRD Q9iZWBXxjL/uIbaGeAywc0DeK1fRYtqUWSn1IPyuj5EOB2pSjRsk0TwSbxAB4YCY0tGY ZaSA== X-Gm-Message-State: ALoCoQlFtQMZaFrd8Qpk7XedNsBmaIE89hYlKjkS0JIkmV2y74UNoIhu/gcy/A1ofhkEh8bSuGb0 X-Received: by 10.236.25.225 with SMTP id z61mr586001yhz.49.1421186510883; Tue, 13 Jan 2015 14:01:50 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.158.132 with SMTP id h126ls273722ioe.28.gmail; Tue, 13 Jan 2015 14:01:50 -0800 (PST) X-Received: by 10.66.124.225 with SMTP id ml1mr667076pab.142.1421186510196; Tue, 13 Jan 2015 14:01:50 -0800 (PST) Original-Received: from mail-pa0-x230.google.com (mail-pa0-x230.google.com. [2607:f8b0:400e:c03::230]) by mx.google.com with ESMTPS id xg4si28383409pab.170.2015.01.13.14.01.50 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 13 Jan 2015 14:01:50 -0800 (PST) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::230 as permitted sender) client-ip=2607:f8b0:400e:c03::230; Original-Received: by mail-pa0-f48.google.com with SMTP id rd3so6107536pab.7 for ; Tue, 13 Jan 2015 14:01:50 -0800 (PST) X-Received: by 10.66.246.130 with SMTP id xw2mr840510pac.32.1421186509967; Tue, 13 Jan 2015 14:01:49 -0800 (PST) Original-Received: from [172.20.10.2] ([121.54.44.90]) by mx.google.com with ESMTPSA id ms5sm5553978pbb.59.2015.01.13.14.01.48 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 13 Jan 2015 14:01:49 -0800 (PST) In-Reply-To: X-Mailer: Apple Mail (2.1993) 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:c03::230 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:15640 Archived-At: --Apple-Mail=_C9E71FB9-BB27-4A12-9767-829B1EBBEF62 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 > On 2015=E2=80=9301=E2=80=9314, at 5:57 AM, Richard Smith wrote: >=20 > (I was talking about FENV_ACCESS, not FP_CONTRACT. Dealing with FP_CONTRA= CT is easy; just don't do contractions in constexpr evaluation.) Yes, and I=E2=80=99m talking about the intersection of FENV_ACCESS and FP_C= ONTRACT. You mentioned interaction between constexpr and FENV_ACCESS. Expressions wh= ich are constexpr/contracted will not set overflow bits. FP_CONTRACT is the= C99 analogue to constexpr, although it provides few guarantees. > On reflection, I think this goes further than , since fesetround a= ffects the results of (for instance) floating point addition, too. So there= 's no *new* problem here. =3D) When things are done at compile time, all bets are off. --=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=_C9E71FB9-BB27-4A12-9767-829B1EBBEF62 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8
On 2015=E2=80=9301= =E2=80=9314, at 5:57 AM, Richard Smith <richard@metafoo.co.uk> wrote:

(I was ta= lking about FENV_ACCESS, not FP_CONTRACT. Dealing with FP_CONTRACT is easy;= just don't do contractions in constexpr evaluation.)

Yes, and I=E2=80= =99m talking about the intersection of FENV_ACCESS and FP_CO= NTRACT.

You mentioned interactio= n between constexpr and FENV_A= CCESS. Expressions which are const= expr/contracted will not set overflow bits. FP_CONTRACT is the C99 analogue t= o constexpr, although it prov= ides few guarantees.

On reflection, I think this= goes further than <cmath>, since fesetround affects the results of (= for instance) floating point addition, too. So there's no *new* problem her= e. =3D)

When things are done at compile time, all bets are off.

--

---
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>.
--Apple-Mail=_C9E71FB9-BB27-4A12-9767-829B1EBBEF62-- .