220 30844 article Path: news.gmane.org!.POSTED!not-for-mail From: Rein Halbersma Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Detecting compile-time evaluation Date: Thu, 9 Feb 2017 21:10:18 +0100 Lines: 95 Approved: news@gmane.org Message-ID: References: <86a47916-27c3-4e29-862f-9b4e1f105c1c@isocpp.org> <12459132.29Ej4iibtf@tjmaciei-mobl1> <24bee7ba-de92-49e5-b5c0-e033f4b86f89@isocpp.org> <1707568.ZBltNqqEby@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a1142a430faf26005481e917e X-Trace: blaine.gmane.org 1486671028 26736 195.159.176.226 (9 Feb 2017 20:10:28 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 9 Feb 2017 20:10:28 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCMYZKMJV4IRBK4Z6PCAKGQEEFIJYTY@isocpp.org Thu Feb 09 21:10:20 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f199.google.com ([209.85.161.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cbv2o-0006AP-J0 for gclcip-std-proposals@m.gmane.org; Thu, 09 Feb 2017 21:10:18 +0100 Original-Received: by mail-yw0-f199.google.com with SMTP id v73sf16520338ywg.2 for ; Thu, 09 Feb 2017 12:10:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=BieiMG6QHhPg2pioIXHK7y3VUcl7b5Jvn9+FBh3GOU4=; b=qp9zvxRHFTJy/gppEjLFWSXRTv7yF0dbJCNIbZqqxUNyAlN705ogUc015nVcd5fM06 z/KbNOyJ0qwzQiAJyaCKbs8C7joHyIaqbylxi1pOPxar1ep5NXQU+dBONwswU2phd0pe Meg0kEeqlPM0AcZ6b8QohfKc6ehp7SqdE3cVw2EEH2iYn0AAYCE/xsaIhaCvr60GdzPn U3bJZZgXMTq3KJ1cRksPW01PYYclGYB1YuyqByoCje7lZo6dAFewAdatNhYVILAHRHkx W+ne7RcXFHyS2sZegH91zPRPRkLXsXYB7/cZEx8B5sXRmOteu483DDNKO61fd8GttLMh 5N7g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=BieiMG6QHhPg2pioIXHK7y3VUcl7b5Jvn9+FBh3GOU4=; b=uLtGJoKQro4jvzOY6nGqXHiRDYg3sZfJr6eE3/DNKEVbgoLva4ciLhmInovp5RqhwG ByPYngLPldusUA2D/+r6KN/CFKQMpUS/eHzVeBiZeSbsZyA2OYomdUBtgjyRkHEzDR6n +x4aVCzTqwRivZtZVOxjN0LjScVHw2sg9x9GFeHImpwDlEBJKCRIkYQbQ5RoyI0sJvn0 ANe85FkQiN70uAmI0jXDKRdAYtotWKBr4uPz7SsCxZq0491p950qkV9MkbuRUavTZ8ca JosfNKAWCFCaj/vIBSrLBEUAEfpHYsdlc8DiKLC4MYUYZNu/hOPIcLEx+OBUByuViAZf 037A== X-Gm-Message-State: AMke39mLEgMkcR7dItzyWfYioOUXK4i6Jwoi6l2NUohMTSRngItXS8l1j2Ph8BmrnszWmQ== X-Received: by 10.13.212.2 with SMTP id w2mr1820086ywd.105.1486671019994; Thu, 09 Feb 2017 12:10:19 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.11.115 with SMTP id p48ls20899051otd.19.gmail; Thu, 09 Feb 2017 12:10:19 -0800 (PST) X-Received: by 10.55.138.196 with SMTP id m187mr5018045qkd.210.1486671019260; Thu, 09 Feb 2017 12:10:19 -0800 (PST) Original-Received: from mail-qk0-x243.google.com (mail-qk0-x243.google.com. [2607:f8b0:400d:c09::243]) by mx.google.com with ESMTPS id i130si8826453qki.71.2017.02.09.12.10.19 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 09 Feb 2017 12:10:19 -0800 (PST) Received-SPF: pass (google.com: domain of rhalbersma@gmail.com designates 2607:f8b0:400d:c09::243 as permitted sender) client-ip=2607:f8b0:400d:c09::243; Original-Received: by mail-qk0-x243.google.com with SMTP id u25so2223171qki.2 for ; Thu, 09 Feb 2017 12:10:19 -0800 (PST) X-Received: by 10.55.24.76 with SMTP id j73mr4646614qkh.267.1486671018903; Thu, 09 Feb 2017 12:10:18 -0800 (PST) Original-Received: by 10.55.131.4 with HTTP; Thu, 9 Feb 2017 12:10:18 -0800 (PST) In-Reply-To: <1707568.ZBltNqqEby@tjmaciei-mobl1> X-Original-Sender: rhalbersma@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of rhalbersma@gmail.com designates 2607:f8b0:400d:c09::243 as permitted sender) smtp.mailfrom=rhalbersma@gmail.com; dmarc=pass (p=NONE sp=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:30844 Archived-At: --001a1142a430faf26005481e917e Content-Type: text/plain; charset=UTF-8 On Thu, Feb 9, 2017 at 9:04 PM, Thiago Macieira wrote: > On quinta-feira, 9 de fevereiro de 2017 11:29:26 PST rhalbersma@gmail.com > wrote: > > That is inaccurate: builtin bit-twiddling in constexpr contexts has been > > supported since Clang 3.4. > > > > int main() > > { > > static_assert(__builtin_ctz(0x8) == 3, ""); > > } > > > > http://melpon.org/wandbox/permlink/atER2z2uVzSPxzjA > > Well, experience proves you wrong. This used to fail with Clang that came > with > Xcode 6.4, which says: > > Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn) > > So unless Apple broke something, then 3.5 didn't work. > > (Testing with gcc.godbolt.org shows that it's actually Apple's fault > On Linux, this has been working for at least 3 years now, too bad if XCode didn't work out for you. -- 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. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAGBGO5WBAOZd-L9_sC7GQe8%2B7H26AxAxYB_87EDTTfGhM%3Djnvw%40mail.gmail.com. --001a1142a430faf26005481e917e Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Thu, Feb 9, 2017 at 9:04 PM, Thiago Macieira <<= a href=3D"mailto:thiago@macieira.org" target=3D"_blank">thiago@macieira.org= > wrote:
On quinta-feira, 9= de fevereiro de 2017 11:29:26 PST = rhalbersma@gmail.com
wrote:
> That is inaccurate: builtin bit-twiddling in constexp= r contexts has been
> supported since Clang 3.4.
>
> int main()
> {
>=C2=A0 =C2=A0 =C2=A0static_assert(__builtin_ctz(0x8) =3D=3D 3, &qu= ot;");
> }
>
> http://melpon.org/wandbox/permlink/atER= 2z2uVzSPxzjA

Well, experience proves you wrong. This used to fail with Clang that= came with
Xcode 6.4, which says:

Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn)

So unless Apple broke something, then 3.5 didn't work.

(Testing with gcc.godbolt.org shows that it's actually Apple's fa= ult

On Linux, this has been working for= at least 3 years now, too bad if XCode didn't work out for you.=C2=A0<= /div>

--
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To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAGBGO5WBAOZd= -L9_sC7GQe8%2B7H26AxAxYB_87EDTTfGhM%3Djnvw%40mail.gmail.com.
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