From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Stefan Kangas Newsgroups: gmane.emacs.bugs Subject: bug#39233: .elc file - possibly outdated backward compatibility comments Date: Fri, 24 Jan 2020 17:08:20 +0100 Message-ID: <875zh0alcb.fsf@marxist.se> References: <87zhefkhi9.fsf@marxist.se> <835zh1rz1o.fsf@gnu.org> <878slwgbvd.fsf@gnus.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="90588"; 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 Monnier To: Lars Ingebrigtsen Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Fri Jan 24 17:09:12 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 1iv1WB-000NVo-7X for geb-bug-gnu-emacs@m.gmane-mx.org; 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d=marxist.se; s=default; h=Content-Type:MIME-Version:Message-ID:Date:References: In-Reply-To:Subject:Cc:To:From:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=nzBa+K1AYwRXGTeyEgWm38kAb0ZvarPrlfaGTcZGJHo=; b=gKCAL6YYHLwAZFj6LRZvX3Tk3p K0o8PrSOUt0wmdvaW3oov9mjFJftiXw3mOOTSjadd6Vj0iMTQRvHnJYTZypfnLHP3vnIB1IZ+zVBX VEaPXleO+tL2M634FQ+l2DzgJSL+hXy3QB+hROnwOqqFRrkdFqAzhxoxBhdbtQ60Q5mkMLC/gQNFo UN5FDC0qQyj1+BdkjA13SaCighuECDT11MJbOtkP9d9zg/5vez/6V7x5BJprkdacpuEK010bOogTu 3wlhKO5yPDArhomInojjEH+en9WD5LCSRN3iwe4k0JnwBKAIMb95FSGy782Of2R4AbBAW4QRHauPF dssR3HyQ==; Original-Received: from h-70-69.a785.priv.bahnhof.se ([155.4.70.69]:37932 helo=localhost) by ted.gofardesign.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92) (envelope-from ) id 1iv1VO-000xAz-4v; Fri, 24 Jan 2020 11:08:22 -0500 In-Reply-To: <878slwgbvd.fsf@gnus.org> (Lars Ingebrigtsen's message of "Fri, 24 Jan 2020 15:36:22 +0100") X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - ted.gofardesign.uk X-AntiAbuse: Original Domain - debbugs.gnu.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - marxist.se X-Get-Message-Sender-Via: ted.gofardesign.uk: authenticated_id: stefan@marxist.se X-Authenticated-Sender: ted.gofardesign.uk: stefan@marxist.se 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:175233 Archived-At: Lars Ingebrigtsen writes: > 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 code is only run during byte-compilation, not when loading the file. We add the lines, and then use them as an anchor to find the location to add a version test for Emacs <23 if there are any utf-8 non-ASCII characters. You could try on Emacs 26.1 `M-x load-file RET cperl-mode.elc RET' using a file byte-compiled with current master to verify. Best regards, Stefan Kangas