From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: Why is it so difficult to get a Lisp backtrace? Date: Sat, 25 Jun 2022 19:45:49 +0000 Message-ID: References: <87edzchi3d.fsf@gnus.org> <83sfnsadow.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="14028"; mail-complaints-to="usenet@ciao.gmane.io" Cc: larsi@gnus.org, emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sat Jun 25 21:48:13 2022 Return-path: Envelope-to: ged-emacs-devel@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 1o5BlM-0003Qe-Te for ged-emacs-devel@m.gmane-mx.org; Sat, 25 Jun 2022 21:48:12 +0200 Original-Received: from localhost ([::1]:54864 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o5BlL-0002uN-44 for ged-emacs-devel@m.gmane-mx.org; Sat, 25 Jun 2022 15:48:11 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:39140) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o5BjM-00023v-Od for emacs-devel@gnu.org; Sat, 25 Jun 2022 15:46:08 -0400 Original-Received: from colin.muc.de ([193.149.48.1]:64290 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.90_1) (envelope-from ) id 1o5BjJ-00032N-Mo for emacs-devel@gnu.org; Sat, 25 Jun 2022 15:46:08 -0400 Original-Received: (qmail 78233 invoked by uid 3782); 25 Jun 2022 19:45:50 -0000 Original-Received: from acm.muc.de (p4fe15baa.dip0.t-ipconnect.de [79.225.91.170]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Sat, 25 Jun 2022 21:45:50 +0200 Original-Received: (qmail 7533 invoked by uid 1000); 25 Jun 2022 19:45:49 -0000 Content-Disposition: inline In-Reply-To: <83sfnsadow.fsf@gnu.org> X-Submission-Agent: TMDA/1.3.x (Ph3nix) X-Primary-Address: acm@muc.de Received-SPF: pass client-ip=193.149.48.1; envelope-from=acm@muc.de; helo=mail.muc.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:291624 Archived-At: Hello, Eli. On Sat, Jun 25, 2022 at 19:51:59 +0300, Eli Zaretskii wrote: > > Date: Sat, 25 Jun 2022 15:59:52 +0000 > > Cc: emacs-devel@gnu.org > > From: Alan Mackenzie > > Another thing I'd like to be able to do is get a backtrace when > > there's an error in font-locking during redisplay. That's a whole > > order of magnitude difference in complexity. > The only two ways of having that, AFAIK, are: > . emit the backtrace int *Messages* > . add the backtrace to delayed-warnings-list Why can't the backtrace be generated and stored, and only displayed at a subsequent redisplay (probably the next one)? > You _cannot_ have a *backtrace* buffer popping up when the error comes > from some Lisp called by redisplay, because we explicitly disable > that, and for a good reason. It would increase the complexity of redisplay, making it fragile, for no good reason, yes. -- Alan Mackenzie (Nuremberg, Germany).