From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Lars Ingebrigtsen Newsgroups: gmane.emacs.bugs Subject: bug#39233: .elc file - possibly outdated backward compatibility comments Date: Fri, 24 Jan 2020 15:36:22 +0100 Message-ID: <878slwgbvd.fsf@gnus.org> References: <87zhefkhi9.fsf@marxist.se> <835zh1rz1o.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="43365"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: 39233@debbugs.gnu.org, stefan@marxist.se To: Stefan Monnier Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Fri Jan 24 15:37:11 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1iv059-000BFA-Bv for geb-bug-gnu-emacs@m.gmane-mx.org; Fri, 24 Jan 2020 15:37:11 +0100 Original-Received: from localhost ([::1]:43140 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iv058-0001bJ-GQ for geb-bug-gnu-emacs@m.gmane-mx.org; Fri, 24 Jan 2020 09:37:10 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:45078) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iv051-0001bA-D1 for bug-gnu-emacs@gnu.org; Fri, 24 Jan 2020 09:37:04 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iv050-00011q-79 for bug-gnu-emacs@gnu.org; Fri, 24 Jan 2020 09:37:03 -0500 Original-Received: from debbugs.gnu.org ([209.51.188.43]:47641) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1iv050-00011i-3s for bug-gnu-emacs@gnu.org; Fri, 24 Jan 2020 09:37:02 -0500 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1iv050-0002cB-1l for bug-gnu-emacs@gnu.org; Fri, 24 Jan 2020 09:37:02 -0500 X-Loop: help-debbugs@gnu.org Resent-From: Lars Ingebrigtsen Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Fri, 24 Jan 2020 14:37:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 39233 X-GNU-PR-Package: emacs Original-Received: via spool by 39233-submit@debbugs.gnu.org id=B39233.157987659510011 (code B ref 39233); Fri, 24 Jan 2020 14:37:02 +0000 Original-Received: (at 39233) by debbugs.gnu.org; 24 Jan 2020 14:36:35 +0000 Original-Received: from localhost ([127.0.0.1]:53614 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1iv04Z-0002bP-5k for submit@debbugs.gnu.org; Fri, 24 Jan 2020 09:36:35 -0500 Original-Received: from quimby.gnus.org ([95.216.78.240]:39372) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1iv04X-0002bC-Tl for 39233@debbugs.gnu.org; Fri, 24 Jan 2020 09:36:34 -0500 Original-Received: from cm-84.212.202.86.getinternet.no ([84.212.202.86] helo=marnie) by quimby.gnus.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1iv04N-0007L1-5J; Fri, 24 Jan 2020 15:36:25 +0100 In-Reply-To: (Stefan Monnier's message of "Fri, 24 Jan 2020 09:22:49 -0500") X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.51.188.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:175221 Archived-At: Stefan Monnier writes: >> Will these changes still allow old Emacs binaries to load *.elc files >> compiled by Emacs after these changes? > > New Emacsen loading old .elc won't be affected. > > Old Emacsen loading .elc files compiled by new Emacsen is something that > has always been risky, tho it has sometimes worked. My proposal is to > make it emit a warning (so it will work as much as it does now, but > will bring to the attention of the user that it's in murky territory). Reading the fix for the compilation problem, it was: - (search-forward "\n;;; This file uses") It's quite possible that I misunderstand the patch, but doesn't this mean that (until a couple of days ago), Emacs assumed that that string exists in .elc files unconditionally. And now it does, so if you try to use an Emacs from last week to load .elc files from this week, that week-old Emacs will break? That doesn't seem optimal. -- (domestic pets only, the antidote for overdose, milk.) bloggy blog: http://lars.ingebrigtsen.no