From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Andreas Schwab Newsgroups: gmane.emacs.bugs Subject: bug#54501: Segfault on recursive structure Date: Tue, 22 Mar 2022 16:02:57 +0100 Message-ID: <87y212do7y.fsf@igel.home> References: <87cziekpwk.fsf@gnus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="18404"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.92 (gnu/linux) Cc: Andy Gaynor , 54501@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 Tue Mar 22 16:04:44 2022 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 1nWg3w-0004WJ-Ks for geb-bug-gnu-emacs@m.gmane-mx.org; Tue, 22 Mar 2022 16:04:44 +0100 Original-Received: from localhost ([::1]:33788 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nWg3v-0002F5-Io for geb-bug-gnu-emacs@m.gmane-mx.org; Tue, 22 Mar 2022 11:04:43 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:56758) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nWg3G-0002Eu-Er for bug-gnu-emacs@gnu.org; Tue, 22 Mar 2022 11:04:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:47712) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1nWg3G-0003Nj-5P for bug-gnu-emacs@gnu.org; Tue, 22 Mar 2022 11:04:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1nWg3F-0006BU-Vk for bug-gnu-emacs@gnu.org; Tue, 22 Mar 2022 11:04:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Andreas Schwab Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Tue, 22 Mar 2022 15:04:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 54501 X-GNU-PR-Package: emacs Original-Received: via spool by 54501-submit@debbugs.gnu.org id=B54501.164796138323707 (code B ref 54501); Tue, 22 Mar 2022 15:04:01 +0000 Original-Received: (at 54501) by debbugs.gnu.org; 22 Mar 2022 15:03:03 +0000 Original-Received: from localhost ([127.0.0.1]:41609 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1nWg2J-0006AJ-2V for submit@debbugs.gnu.org; Tue, 22 Mar 2022 11:03:03 -0400 Original-Received: from mail-out.m-online.net ([212.18.0.9]:55657) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1nWg2G-00069s-OQ for 54501@debbugs.gnu.org; Tue, 22 Mar 2022 11:03:01 -0400 Original-Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 4KNF8y5ZT0z1r1fd; Tue, 22 Mar 2022 16:02:58 +0100 (CET) Original-Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 4KNF8y3fDPz1qqkD; Tue, 22 Mar 2022 16:02:58 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Original-Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id mzs_ubkc63w4; Tue, 22 Mar 2022 16:02:57 +0100 (CET) X-Auth-Info: 3h4TvNA32yUF57756a8IAuPeriLQHCwCu4swMwUxBthymbRY/bxVQ906JQ75mBxU Original-Received: from igel.home (ppp-46-244-174-87.dynamic.mnet-online.de [46.244.174.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Tue, 22 Mar 2022 16:02:57 +0100 (CET) Original-Received: by igel.home (Postfix, from userid 1000) id 4D4BA2C3622; Tue, 22 Mar 2022 16:02:57 +0100 (CET) X-Yow: There's enough money here to buy 5000 cans of Noodle-Roni! In-Reply-To: <87cziekpwk.fsf@gnus.org> (Lars Ingebrigtsen's message of "Tue, 22 Mar 2022 15:44:43 +0100") X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list 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:228765 Archived-At: On Mär 22 2022, Lars Ingebrigtsen wrote: > So this bug report is about two things. The first is that this reads to > (nil): > > #0=#0# > > Which seems odd. Reading #0=#1# signals an error, but it's not > immediately clear to me whether #0=#0# is totally nonsensical or not. > And if not, is (nil) the right result? Anybody? That's an side effect of the implementation: (nil) is the placeholder object which #0# then references. > The other thing is more serious, and reading the following will segfault > your Emacs, so don't do that: > > #0=[#1=(#0# . #1#)] > > Now, Emacs segfaults on trying to gc a number of recursive objects > (especially ones that recurse in the `car'), but this seems to actually > segfault in the reader. Is it obvious to anybody why? Does it crash in substitute_object_recurse? -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."