From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Bug#38708: eq vs eql in byte-compiled code Date: Sat, 4 Jan 2020 11:33:02 -0800 Organization: UCLA Computer Science Department Message-ID: References: <8cd1b5b2-b94e-ce64-0d70-c1b8b012d685@cs.ucla.edu> <1e0940ff-e418-bafc-66d3-72b562b2c65b@cs.ucla.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="240152"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 Cc: =?UTF-8?Q?Mattias_Engdeg=c3=a5rd?= , Pip Cet , emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Jan 04 20:33:13 2020 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1inpAf-0010LJ-6N for ged-emacs-devel@m.gmane.org; Sat, 04 Jan 2020 20:33:13 +0100 Original-Received: from localhost ([::1]:36304 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1inpAd-0008Hn-VK for ged-emacs-devel@m.gmane.org; Sat, 04 Jan 2020 14:33:11 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:52051) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1inpAY-0008He-BE for emacs-devel@gnu.org; Sat, 04 Jan 2020 14:33:07 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1inpAX-0003Dc-9N for emacs-devel@gnu.org; Sat, 04 Jan 2020 14:33:06 -0500 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:50922) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1inpAX-0003BE-3W for emacs-devel@gnu.org; Sat, 04 Jan 2020 14:33:05 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id B9722160076; Sat, 4 Jan 2020 11:33:03 -0800 (PST) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id BrPHrewmf_ak; Sat, 4 Jan 2020 11:33:03 -0800 (PST) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id E44AD160078; Sat, 4 Jan 2020 11:33:02 -0800 (PST) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id QMCaqEdqssoZ; Sat, 4 Jan 2020 11:33:02 -0800 (PST) Original-Received: from [192.168.1.9] (cpe-23-242-74-103.socal.res.rr.com [23.242.74.103]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id A7D08160076; Sat, 4 Jan 2020 11:33:02 -0800 (PST) In-Reply-To: Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 131.179.128.68 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:243932 Archived-At: On 1/4/20 10:54 AM, Stefan Monnier wrote: >> * src/alloc.c (make_pure_bignum): Remove, as we can=E2=80=99t copy (mu= ch >> less purecopy) bignums any more. > Sounds dangerous: it means that pure objects which point to bignums > could end up with dangling pointers because the GC won't see those > pointers and will then GC the corresponding bignum. That dangerous thing can't happen, as the change causes purecopy to signa= l an error when given a bignum. That is, bignums fall into the same category a= s markers, overlays and other objects where purecopy signals an error. Sinc= e these objects are not used in the early phase of building that calls purecopy, = this should not be an issue.