220 30863 article Path: news.gmane.org!.POSTED!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Detecting compile-time evaluation Date: Fri, 10 Feb 2017 07:28:08 -0800 (PST) Lines: 65 Approved: news@gmane.org Message-ID: References: <86a47916-27c3-4e29-862f-9b4e1f105c1c@isocpp.org> <5b081db0-cc7b-4a5f-b9fe-b9f8ae7ab9f7@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_799_139306248.1486740488864" X-Trace: blaine.gmane.org 1486740499 15258 195.159.176.226 (10 Feb 2017 15:28:19 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 10 Feb 2017 15:28:19 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBDVY67CAKGQEOSN2AVA@isocpp.org Fri Feb 10 16:28:14 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f71.google.com ([209.85.213.71]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1ccD7K-0003O9-2X for gclcip-std-proposals@m.gmane.org; Fri, 10 Feb 2017 16:28:10 +0100 Original-Received: by mail-vk0-f71.google.com with SMTP id n125sf21858760vke.0 for ; Fri, 10 Feb 2017 07:28:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=Og4f86ex0w74XCzl0b3FEaKZ9Q3I+ni+jp8Zstolw9Q=; b=zJpjA/Bp+oi4GYuAJElr1HO/VrGE79H0pKMloJAgYT9dtWrke2RW0zbSBKRyCT/sFc U393++aWH8dEUuI0yE8/8VacgelAeOGn66dcsgeaxT6I9YAWl10W/u1VdDzYLL2S/elu 0h12vgAJmJ+mWc9l1OsHohWpMI/n4H128PBS9bYzYDSl51FQJuB8W+/X6n38crH5AXWU DyVe0CuLEjP7nDQyH/sPyDWZ9kOdwlhNE4DFSbVKzWmkpY73+Wuo5vgLJsFO05yWdOMh T0Yhtniyk/QQ1IRJXsXUntOp+0UkEE3riqKBDIauszmZ8Hniv7xWlG4ynM9Jn5NseLm0 9mHA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=Og4f86ex0w74XCzl0b3FEaKZ9Q3I+ni+jp8Zstolw9Q=; b=oBnX3L8/SHlUlzkfkEExWZH67DGjH29VAE/sJKtcQHC0tVMlwcYNxX52/PMWJgZ9pP MQ1N34khgzVBPsV3SXKnhSl7HmrbToM+fqck+j1qFzP+gurtFMIRw43ScD3LJ8I5aiFz AY279btUcMIMuMXuliEJsvIeScxYtxRPwdBSjAOW1kGD1y3cGn633HHIXlyFNcOVCOLR uDCADygsfMcAWBQcmhsRKDXGOaO/77FzuaOnK89YmHK38OfD8YzDwBDIFbAa75gFmH2W 2SRdZe0RXYFTuE8hnTIl5523bSHWBBH4ep4d3Ssk+LTPhqcj17aXyqglI2XTYjgZkRie p6Dg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=Og4f86ex0w74XCzl0b3FEaKZ9Q3I+ni+jp8Zstolw9Q=; b=M3a6t/XhBU3AciBitXCVUhqFfuAMSYjTd8SmRW5epu6UYJY4ai++HNUrU8yFBUkkeM XHqMhA0dPLcsOe++ZhU8gWcqxB4uq2kncv4y366qMzoqV6MazFq2gRgUXJ3wqVcLH2zg D70tWEnpa0qMWWv7yBl8X+C8g/GhLUiI2NEae1hxsN9rawS8bayYuZVcQQ4Q9BspseUl nLXJTxssaIJqtzSIpCuUHHJU2DPtW7bj3McNpskdY8nSR58qn6j+cyrmuIWTOmMM68yO KUQrxNozArRalcS5+Tf0BVdmBFkOiRURJiNbywOoMcmKdSgltyzrGaI8Z8vGlu9sJMtB D+LA== X-Gm-Message-State: AMke39mLrPNNRkmFFZQFUby9tSWo+/7TAIv/ohrCxUKdC/du7xa9Dd0YG/8fLw4bAbCcqw== X-Received: by 10.176.85.94 with SMTP id u30mr2484651uaa.1.1486740495548; Fri, 10 Feb 2017 07:28:15 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.17.23 with SMTP id g23ls17937486ote.24.gmail; Fri, 10 Feb 2017 07:28:14 -0800 (PST) X-Received: by 10.157.4.105 with SMTP id 96mr712848otc.17.1486740494856; Fri, 10 Feb 2017 07:28:14 -0800 (PST) In-Reply-To: <5b081db0-cc7b-4a5f-b9fe-b9f8ae7ab9f7@isocpp.org> X-Original-Sender: jmckesson@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:30863 Archived-At: ------=_Part_799_139306248.1486740488864 Content-Type: multipart/alternative; boundary="----=_Part_800_1015040977.1486740488864" ------=_Part_800_1015040977.1486740488864 Content-Type: text/plain; charset=UTF-8 On Friday, February 10, 2017 at 7:35:38 AM UTC-5, Gonzalo BG wrote: > > A peril of "if constexpr()"-like solutions is that the compiler might want > to evaluate a block of a non constexpr function at compile-time, in which > case it could make sense to make "if constexpr()" also work in > non-constexpr functions, and to return true if the current > context/scope/block is being evaluated at compile-time, independently of > whether the outer function is or isn't being evaluated at compile-time. > I'm not sure what would keep `if constexpr()` from working under those circumstances. You would simply define it to work if the compiler chooses to execute the function at compile time. -- 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/a461e0af-67a6-491e-896f-c5d23826d407%40isocpp.org. ------=_Part_800_1015040977.1486740488864 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Friday, February 10, 2017 at 7:35:38 AM UTC-5, Gonzalo = BG wrote:
A peril of "if constexpr()"-like solutions is that the compiler = might want to evaluate a block of a non constexpr function at compile-time,= in which case it could make sense to make "if constexpr()" also = work in non-constexpr functions, and to return true if the current context/= scope/block is being evaluated at compile-time, independently of whether th= e outer function is or isn't being evaluated at compile-time.

I'm not sure what would keep `if constexpr()` f= rom working under those circumstances. You would simply define it to work i= f the compiler chooses to execute the function at compile time.

--
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.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/a461e0af-67a6-491e-896f-c5d23826d407= %40isocpp.org.
------=_Part_800_1015040977.1486740488864-- ------=_Part_799_139306248.1486740488864-- .