From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#39977: 28.0.50; Unhelpful stack trace Date: Tue, 17 Mar 2020 17:51:37 +0200 Message-ID: <83y2rzf08m.fsf@gnu.org> References: <83zhcs80e5.fsf@gnu.org> <83imj88tpt.fsf@gnu.org> <550fbc22-09db-d30b-c194-8f26b5dca05f@gmx.at> <83wo7o6nxs.fsf@gnu.org> <60dd4ced-a2e5-ed17-0570-b7bdd2a557af@gmx.at> <83blozckn2.fsf@gnu.org> <01305dbc-c69b-baf9-f0bf-1e5b8c04d970@gmx.at> <83y2s2bswl.fsf@gnu.org> <3ac189d0-5d05-fdf9-0922-0c464b1b17c3@gmx.at> <83k13lbgux.fsf@gnu.org> <83d09cb9gz.fsf@gnu.org> <69a74f9e-079b-a771-0213-f60ed0bf5720@gmx.at> Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="18060"; mail-complaints-to="usenet@ciao.gmane.io" Cc: enometh@meer.net, 39977@debbugs.gnu.org To: martin rudalics Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Tue Mar 17 17:19:51 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 1jEEwZ-0004cB-SS for geb-bug-gnu-emacs@m.gmane-mx.org; Tue, 17 Mar 2020 17:19:51 +0100 Original-Received: from localhost ([::1]:35810 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jEEwY-0001X4-PN for geb-bug-gnu-emacs@m.gmane-mx.org; Tue, 17 Mar 2020 12:19:50 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:38246) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jEEWd-0007Fp-By for bug-gnu-emacs@gnu.org; Tue, 17 Mar 2020 11:53:04 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jEEWc-0003wS-2q for bug-gnu-emacs@gnu.org; Tue, 17 Mar 2020 11:53:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:33472) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1jEEWb-0003ux-RE for bug-gnu-emacs@gnu.org; Tue, 17 Mar 2020 11:53:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jEEWb-0004Ig-Oc for bug-gnu-emacs@gnu.org; Tue, 17 Mar 2020 11:53:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Tue, 17 Mar 2020 15:53:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 39977 X-GNU-PR-Package: emacs Original-Received: via spool by 39977-submit@debbugs.gnu.org id=B39977.158446032216464 (code B ref 39977); Tue, 17 Mar 2020 15:53:01 +0000 Original-Received: (at 39977) by debbugs.gnu.org; 17 Mar 2020 15:52:02 +0000 Original-Received: from localhost ([127.0.0.1]:39445 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jEEVe-0004HU-Iu for submit@debbugs.gnu.org; Tue, 17 Mar 2020 11:52:02 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:50386) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jEEVd-0004H0-HK for 39977@debbugs.gnu.org; Tue, 17 Mar 2020 11:52:01 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:36769) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1jEEVX-0007y8-P9; Tue, 17 Mar 2020 11:51:55 -0400 Original-Received: from [176.228.60.248] (port=1323 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1jEEVT-00072c-Sg; Tue, 17 Mar 2020 11:51:55 -0400 In-Reply-To: <69a74f9e-079b-a771-0213-f60ed0bf5720@gmx.at> (message from martin rudalics on Tue, 17 Mar 2020 10:38:11 +0100) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] 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:177457 Archived-At: > Cc: enometh@meer.net, 39977@debbugs.gnu.org > From: martin rudalics > Date: Tue, 17 Mar 2020 10:38:11 +0100 > > > Why does it matter which SELECTED_FRAME crashes? > > Because the next crash may happen at some time in the future. Why not > cure the first crash we have right away? If we can cure it, sure. But I don't yet see what kind of cure are you suggesting. And in any case, the cure is not in SELECTED_FRAME. > >> >> As far as frame.c is concerned, it should do something like in the > >> >> attached patch. > >> > > >> > We cannot punt like that in the display engine. > >> > >> Why not? > > > > Because we must have a frame that we were supposed to redisplay. > > Either we are miscommunicating or I' m just dumb. I would in no way > restrict the display engine in choosing whatever live frame it wants to > redisplay. The original crash, and the crash you reported a couple of messages upthread, are both in redisplay, though. So I'm looking for a solution to those. Assigning some arbitrary value to a local variable and/or switching to a different frame can be such solutions, albeit not optimal ones; the changes you propose for frame.c cannot. So I'm still unsure what exactly would you propose for the display engine to do when it needs to examine the selected frame and discovers that this frame is invalid. > > The display engine doesn't select frames to show them to the user, it > > selects them to redraw their windows. So the considerations what to > > do in this case are different from those we need to consider when the > > user selects a frame. > > As I said above: This is not about the frame its windows it has to > redraw. It's about the display engine trying to select a frame after > it has redrawn (parts of) another frame's windows. The display engine selects a frame because it needs to display something related to that frame. If it cannot select it, it should do something about that, not just punt. > :eval deleted the frame being displayed > > So the display engine is, in principle, aware of one incarnation of the > problem - the one where an :eval tries to delete under its feet the > frame it currently tries to redraw and the comment correctly says that > > This is a nonsensical thing to do, > and signaling an error from redisplay might be > dangerous, but we cannot continue with an invalid frame. You are proposing that we find all the places where SELECTED_FRAME is used and fix them one by one? I thought it could be better to fix them all at once as part of SELECTED_FRAME.