220 40669 <5BCC2525.90805@gmx.net> article Path: news.gmane.org!.POSTED!not-for-mail From: Jens Maurer Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Function to compute the absolute value of any integral value including signed minimums Date: Sun, 21 Oct 2018 09:05:09 +0200 Lines: 49 Approved: news@gmane.org Message-ID: <5BCC2525.90805@gmx.net> References: <3f8200be-918a-44a0-a412-6f8f43da1c51@isocpp.org> <3a5821ae-c386-46b4-8e73-4bff8764679c@isocpp.org> <956410ae-7e45-43a7-ae1d-52a92aec6217@isocpp.org> <9d74ddbb-cc68-412a-ae6b-4664660ff12c@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1540105387 22183 195.159.176.226 (21 Oct 2018 07:03:07 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 21 Oct 2018 07:03:07 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux i686; rv:6.0.1) Gecko/20110830 Thunderbird/6.0.1 To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDPMTYGK64JRBJ6KWDPAKGQEHW5G62A@isocpp.org Sun Oct 21 09:03:03 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wr1-f71.google.com ([209.85.221.71]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gE7lP-0005fy-0i for gclcip-std-proposals@m.gmane.org; Sun, 21 Oct 2018 09:03:03 +0200 Original-Received: by mail-wr1-f71.google.com with SMTP id 88-v6sf30905981wrp.21 for ; Sun, 21 Oct 2018 00:05:13 -0700 (PDT) ARC-Seal: i=2; a=rsa-sha256; t=1540105513; cv=pass; d=google.com; s=arc-20160816; b=AxsEaHHSy7qZdJ+sXcgSrzn9nzZKXMFEgWRRXbAqE/KCMtyf4amL4zdXiSrfD0uwPL a9O3zvO0fTmIpN3PmHGzDD6DvYKfVC0gKutcW/tX+JYX14KOc+HygfyQ0alzikdkM2f9 N2d5tSx7/z8JtASX3IE1y21V2XX/yeCq6SMyrFUNWNa5GAcofL0Vs+/BQ0tsw+fHN3fQ Uqu/VjZUlnbY6rLGWNXr1HIufYbrUEUp7MVsPASqIACybSjMkrHHJ1/C/nMzCILjB+mQ yMbMI8SsuPCD9x/FcBnWo1tp2vzFBYfmb9MeI5bhpWKMCvNCxNJ0ZHMjr5PDCrNdMpYn 9Big== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post :list-id:mailing-list:precedence:reply-to:content-transfer-encoding :in-reply-to:references:subject:to:mime-version:user-agent:from:date :message-id:dkim-signature; bh=F4+I1+xo/n28w7UG57zd3twourrUnFWMB6z2I2TRDiw=; b=vwQaZ13ed+mMGmLGtlwO8F7yTgu2XMfJv0MSBg+XOaICu5/SI80Z+hVp/lBaXkc3cA P5mz+CBNlIa3bRE+D3gO8uuITmOGVqY4ryiyI8vLj4gvWOMunxQ7xhoUdP42f7ZsQgKt 27wilwkZVfYOjF/xwphCvU8QSjEIwT9sX6tdKq+YS+dZ5GoRryi3UFZRC9Haz0B4L1QL V/9IT5pOQHLhi2calx8ljt5Lzcipg3ukgPeNVcwK0XXOLfROulvFvb/sQY2LAkol3LLp i/gpfcZu+OcH/nMRFCxZ+LuB2/P7w1Kz6Y6PjjE/h8RV2yftjfPz0pRm63o7o09Nn1C3 qtWQ== ARC-Authentication-Results: i=2; mx.google.com; spf=pass (google.com: domain of jens.maurer@gmx.net designates 212.227.17.22 as permitted sender) smtp.mailfrom=Jens.Maurer@gmx.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-transfer-encoding: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=F4+I1+xo/n28w7UG57zd3twourrUnFWMB6z2I2TRDiw=; b=K0dEieHfb51GV0tsPzCB7XR+Fz6P3f9mkkjnPViX9E5bpCBe76b83Bcb3LMZYaBIsY vlE3d3su6t+F4cxY5OfPnvFhTHuZ1qc9an0QuIMq5e3zVoj3anqlC1Zj+FqtNLZrs92I 3gYx/txMHj71ikkcSBjxzdmtIAA4uKRxNkCFqMFj9PVvnEAYQD0oktmAfjr8fIOLkGVm TWwkfGj0c0fF77KY5eC2gu3bZD8BtLoqpWtbpvZaZ+svkYsA89pG3hwRsuX/alScXtJi bKG0ErayvkbrF5UGV6VZ6CqeomPllj0vK7VVktF3JBBVwEWr/WC71vfj8gFmLoJoLsA5 QW9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :subject:references:in-reply-to:content-transfer-encoding :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=F4+I1+xo/n28w7UG57zd3twourrUnFWMB6z2I2TRDiw=; b=NmUIrzdNiXoc2CJGwVamX+m40XYQEgnSHI4yBt9MjGldSMUH0M6/xZpy5siBFXB2Fv 1TD3rY5K6/9HYSUr7rYDq/Pmi9ZqvsJ4RNwU6oZlHjhKZ5lgOhkybANp6VTvTyK/1Q+S xU4rg1fsRjwzMEu8KGrHshJnpbok3dgidM6qOe7nhslGZr6rNpK7jHfwlsIHPWOiK+JG NkDmDdT6K6BVGtGiLFlmeRGR5e8CQYY0Fe1V3izVW9i4LFzv49TDxabGD74GxR6A3qBl Mtadvhl2YQ6tcxrgESCbJHNWPEk5hMRAvuJczIuHQiZxmx4IxGinNjtYLuExB1tgvBPq X-Gm-Message-State: ABuFfojhSFZZWdH9Sux/G/a9Kzsst15TOEugGT6BADKnZui1+TgZkxp6 g7oMvH+FhUJZKyFVCEqTA9ISXw== X-Google-Smtp-Source: ACcGV61JbQ/eCLR99dOM2S3D0Pw290TxMGZQG0mINqg/nyIUxx9/C3UGVub7Tr2I7zfdZW5oGcNbeA== X-Received: by 2002:a1c:9655:: with SMTP id y82-v6mr1044597wmd.3.1540105513057; Sun, 21 Oct 2018 00:05:13 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 2002:a5d:4e85:: with SMTP id e5-v6ls4085349wru.26.gmail; Sun, 21 Oct 2018 00:05:11 -0700 (PDT) X-Received: by 2002:a5d:514d:: with SMTP id u13-v6mr13564541wrt.299.1540105511365; Sun, 21 Oct 2018 00:05:11 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1540105511; cv=none; d=google.com; s=arc-20160816; b=H8v+RZh9v35gvs1cV0VFcri5TRjC1l7pw5M89xhPMvaPE814CUY8Sqy/mD/RfcLAwa chtLVeK/fLIxyhS1ggnhYYXEHDIPXO3vu2xamPTCVtRE/vETn7NhVlAiyxqPKXV7uPD9 ZLpTFichkhjszDS05AE/FQNPI36ZMPLm301jAkCZd4H8JrdEeRM7DB7L+zz5c2T6Qb/O pYBkEw2G0A94nAljwg66sovWU8x7u58GOb/AK0V0TDRmbMSPZxi2vrL0Iip3h62a5UiJ W9QE1Kz4SjINjQDRza3HCqKzgQHSBl9EDmiTnx08q3XDToDFkUsEwVmIaPg43LsEHEAB mFuA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:in-reply-to:references:subject:to :mime-version:user-agent:from:date:message-id; bh=v1j5j2FRCDJUXeVSjq/C3DQMHEy7lkCe328Q9yn0aMA=; b=IEHuWF7/5UioLVcJ4Ysekao7ZIr+lA9i5PE+R8RSArbOYsEsiT8x1xEZMHBmzNFOrO 5NZW3ecpSy14jvmVN8iFPfyqKX8cokQ8/gktlxpErXD/WBwsYfid4BrN+YJmFI4thF/n cScI7Pr/Fc+aL3Ts1twHG/WzAHg7Bq5EI/p42/5SkYiwtCeirakBEFXC6UxCkUoNEbyz Fgd2S3jFw22e7dV5BkaN25LzD2nKhUhT+yoNXNjQRTsQTLozndou09jd5Y2jm1ALHspO khbOdP/OE3wT0n5QdqHgrCVuPcFJgIoDF9lp+TjqKbaLSx7v1bE3SXni8jJMO0hKBhzV RqZw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of jens.maurer@gmx.net designates 212.227.17.22 as permitted sender) smtp.mailfrom=Jens.Maurer@gmx.net Original-Received: from mout.gmx.net (mout.gmx.net. [212.227.17.22]) by mx.google.com with ESMTPS id j204-v6si7107928wma.24.2018.10.21.00.05.11 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 21 Oct 2018 00:05:11 -0700 (PDT) Received-SPF: pass (google.com: domain of jens.maurer@gmx.net designates 212.227.17.22 as permitted sender) client-ip=212.227.17.22; Original-Received: from [192.168.2.101] ([92.208.230.11]) by mail.gmx.com (mrgmx101 [212.227.17.168]) with ESMTPSA (Nemesis) id 0MIzGn-1gCCvH1X6P-002bvt for ; Sun, 21 Oct 2018 09:05:10 +0200 Original-Received: from [192.168.2.101] ([92.208.230.11]) by mail.gmx.com (mrgmx101 [212.227.17.168]) with ESMTPSA (Nemesis) id 0MIzGn-1gCCvH1X6P-002bvt for ; Sun, 21 Oct 2018 09:05:10 +0200 In-Reply-To: X-Provags-ID: V03:K1:i9RSKy0emyCn8KXF9/TlY7eSW+3eVmKccR76NVaL6ylvcEnGEft orHPXYSUq2OO9tNJLItquCVCEHom+Fkrp+vGWBb65uI45PjUy+eDhQQd3X+e0vLKyhmSq7V X9Sai+mCIgxx9SVHnUdWFLLoba1imx1TGeq0ZDEfFauhhvMGUfQJ8qoV2LcbB8tanPJrdu6 EQLY24h3+djhWB0XW0NMQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:mzwpgKbzLfI=:gicQZz7hzZT7N6/UAnu/gw HvzedEqxrpF1ABZGJuGJf2XrD6r9qd6zG4vFTbYUNYYidOD6CNTru5li84s9n5k08uL4CK5q6 w7Dt9+8Es/QY4RhTxKSHbCFLekcNJTKRwetH4lFIzBhNLsVtruqtxcTuIgemmuHaoyReyC6+y nnULbEuOKG000yZEq+zEyaOG6dihrjG1XUCtqd0ifUh7joDlvxvRkU5d7v7wKBukIghzEEKFl O2pcfRh15KRdx6DacN22uscjdlzuKJmltf0EqZjrtIAWv5EfOtxDA+A/f3G581ju4R45+4SNv QS37i1y4l/dU3SBYClNijHvNy5xz89nWSyeZX8rEimdyeX5J0bb1HAU6cP0/x35sYAhjRMjUg AeZ264/iY08XMSN2Fgmcl2GuxVKB4XDX+TZn+iLokXPJ/qswYHR7XQvTZdnzGwkFm2a9PusQQ NC+FUuVD2d++u0QC6iaYhG/q1wjjdOk9+TMszB0lXRhWyvfWfyRdLqOcoLtvj+KWRQvag9X+X hFDfR4d4EI7M8sJkSpuejZo9t7eV7VthMINJSD9iLqqgk/mHQHDqTInSi/0NUzJ5nFd0/IzSj Wv2FoA6aFPQMUevPaC4dmVL7lerPtaB07U945FjD8MOL9ahgkBJ+Tucxc2lBPMTlztahjCLhN JCufkBRx6U13ShsbICTP+5qO5TtasO3+6Tzy7/1TmCEC5jY1b8FbW7YOpHgxzshdHQFXQXbN+ 7fWYNmQ5wTgMfJYHNg82Jfhh3m8DbREOR+IjARDSRvig4hBdH0xvfm0LZf42m/uZbtzWEC8B X-Original-Sender: Jens.Maurer@gmx.net X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of jens.maurer@gmx.net designates 212.227.17.22 as permitted sender) smtp.mailfrom=Jens.Maurer@gmx.net Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:40669 Archived-At: On 10/21/2018 12:52 AM, JF Bastien wrote: >=20 >=20 > On Sat, Oct 20, 2018 at 1:00 PM Bryce Adelstein Lelbach aka wash > wrote: >=20 > JF? (See question below) >=20 > On Sat, Oct 20, 2018, 7:27 AM > wrote: >=20 > I recently read that their is a paper suggesting integers always = being twos complement should be standardised. If this is the case, would th= e call to the existing std::abs(std::numeric_limits::min()) bec= ome well defined behaviour? >=20 >=20 > http://wg21.link/p0907 >=20 > /Status-quo/ If a signed operation would naturally produce a value th= at is not within the range of the result type, the behavior is undefined. T= he author had hoped to make this well-defined as wrapping (the operations p= roduce the same value bits as for the corresponding unsigned type), but WG2= 1 had strong resistance against this. In particular, the wording surrounding std::abs in the C++ standard is unch= anged "Effects: The abs functions have the semantics specified in the C standard = library for the functions abs, labs, llabs, fabsf, fabs, and fabsl." and C says "The abs, labs, and llabs functions compute the absolute value of an intege= r j. If the result cannot be represented, the behavior is undefined." Jens --=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/5BCC2525.90805%40gmx.net. .