From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#21819: 24.5; Overlay modification function called with wrong arguments Date: Tue, 03 Nov 2015 17:27:43 +0200 Message-ID: <83fv0nw1ao.fsf@gnu.org> References: Reply-To: Eli Zaretskii NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Trace: ger.gmane.org 1446564499 12340 80.91.229.3 (3 Nov 2015 15:28:19 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 3 Nov 2015 15:28:19 +0000 (UTC) Cc: 21819@debbugs.gnu.org To: Yutian Li | =?UTF-8?Q?=E6=9D=8E=E9=9B=A8=E7=94=B0?= Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Tue Nov 03 16:28:10 2015 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZtdVK-0007n5-CK for geb-bug-gnu-emacs@m.gmane.org; Tue, 03 Nov 2015 16:28:10 +0100 Original-Received: from localhost ([::1]:49380 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtdVJ-0000Xt-KY for geb-bug-gnu-emacs@m.gmane.org; Tue, 03 Nov 2015 10:28:09 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:59422) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtdVG-0000Xm-27 for bug-gnu-emacs@gnu.org; Tue, 03 Nov 2015 10:28:07 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZtdVB-0006ue-Vz for bug-gnu-emacs@gnu.org; Tue, 03 Nov 2015 10:28:05 -0500 Original-Received: from debbugs.gnu.org ([208.118.235.43]:60905) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtdVB-0006ua-SV for bug-gnu-emacs@gnu.org; Tue, 03 Nov 2015 10:28:01 -0500 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.80) (envelope-from ) id 1ZtdVB-0001sU-NW for bug-gnu-emacs@gnu.org; Tue, 03 Nov 2015 10:28:01 -0500 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Tue, 03 Nov 2015 15:28:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 21819 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 21819-submit@debbugs.gnu.org id=B21819.14465644707202 (code B ref 21819); Tue, 03 Nov 2015 15:28:01 +0000 Original-Received: (at 21819) by debbugs.gnu.org; 3 Nov 2015 15:27:50 +0000 Original-Received: from localhost ([127.0.0.1]:51613 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1ZtdV0-0001s6-2v for submit@debbugs.gnu.org; Tue, 03 Nov 2015 10:27:50 -0500 Original-Received: from mtaout25.012.net.il ([80.179.55.181]:42823) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1ZtdUf-0001rb-LS for 21819@debbugs.gnu.org; Tue, 03 Nov 2015 10:27:48 -0500 Original-Received: from conversion-daemon.mtaout25.012.net.il by mtaout25.012.net.il (HyperSendmail v2007.08) id <0NX800300W3CAV00@mtaout25.012.net.il> for 21819@debbugs.gnu.org; Tue, 03 Nov 2015 17:25:16 +0200 (IST) Original-Received: from HOME-C4E4A596F7 ([84.94.185.246]) by mtaout25.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0NX80017PW63GA20@mtaout25.012.net.il>; Tue, 03 Nov 2015 17:25:16 +0200 (IST) In-reply-to: X-012-Sender: halo1@inter.net.il X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.15 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 208.118.235.43 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.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:108350 Archived-At: > Date: Tue, 3 Nov 2015 00:24:41 -0800 > From: Yutian Li | 李雨田 > > This happens on both Mac and GNU/Linux with latest release of Emacs. I > also tried the master branch of `git://git.sv.gnu.org/emacs.git` and > it still exists. > > The discussion that led to the discovery of the bug is > [here](https://github.com/capitaomorte/yasnippet/issues/607). There is > a stack trace on the OP. Some guesses in the bottom. There is also > instructions to reproduce this. Thanks. I've read that discussion. Unfortunately, the instruction for reproducing the problem are not clear to me, I'd appreciate if someone could post them here in their entirety, ideally a single Lisp file that needs to be 'load'ed into "emacs -Q" after installing the minimal number of add-on packages that are strictly necessary for reproducing the problem. > The direct cause is the modification hook registered with the overlay > is called with apparently wrong arguments. The hook function is > registered with an overlay in the C++ buffer, but called with `beg` > and `end` referring to positions probably in the `*Messages*` buffer. > As the stack trace shows, Flycheck called `message` to display a > message indicating syntax errors, and `message` somehow invokes the > modification hook function, which was defined in C++ buffer but called > now in `*Messages*` buffer. It is entirely not clear to me how come a call to 'message' caused an overlay modification hook, probably set up by yasnippet, to be invoked. This is crucial information in order to investigate the problem, but AFAICS it's missing from the discussion you cite and from your report. > I traced into the Emacs source file `src/buffer.c`. There is a > function `report_overlay_modification`. It *should* (I guess) be > called with `after` set to `false` and `true` alternatively. But on > the erroneous invocation, it is called with `after` set to `true` > twice consecutively. The first call `_beg` and `_end` are normal small > integer (inside C++ buffer). The second call they are huge and must > refer to the `*Messages*` buffer. Inside the call, it uses a global > array to store overlay modification hook functions. Now it's called > twice consecutively with `after` set to `true`, it must have reused > old hook functions, hence the call to our function with correct > overlay but wrong cursor. Because on a call with `after` set to > `false`, it will "clear" the hook functions. Thanks for looking into this, but without the information showing how we wind up in 'report_overlay_modification' when some Lisp code called 'message', it is impossible to follow your reasoning. E.g., it is quite possible that the Lisp code in question sets up the modification hook incorrectly, or maybe the modification hook should check the value of the current buffer to avoid the problem. In general, 'report_overlay_modification' is called immediately before a change to a buffer that has overlays, and immediately after a change. The value of the AFTER argument depends on which one is it. So just given the fact you see 2 invocations with AFTER set to true does not yet mean there's a problem in Emacs core, it could be a legitimate call due to the fact that *Messages* gets changed when 'message' is called. Thanks.