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.bugs Subject: bug#41988: 28.0.50; Edebug unconditionally instruments definitions with &define specs Date: Sun, 9 Aug 2020 16:35:23 +0000 Message-ID: <20200809163523.GB26635@ACM> References: <20200621234816.88427.qmail@mail.muc.de> <20200808145948.GA10181@ACM> 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="31386"; mail-complaints-to="usenet@ciao.gmane.io" Cc: 41988@debbugs.gnu.org To: Philipp Stephani Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sun Aug 09 18:36:12 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 1k4oIt-00085C-SQ for geb-bug-gnu-emacs@m.gmane-mx.org; Sun, 09 Aug 2020 18:36:11 +0200 Original-Received: from localhost ([::1]:54528 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k4oIs-0007Ym-TD for geb-bug-gnu-emacs@m.gmane-mx.org; Sun, 09 Aug 2020 12:36:10 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:36984) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k4oIk-0007YX-Nh for bug-gnu-emacs@gnu.org; Sun, 09 Aug 2020 12:36:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:50006) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1k4oIk-0008Kq-ET for bug-gnu-emacs@gnu.org; Sun, 09 Aug 2020 12:36:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1k4oIk-0003FO-Az for bug-gnu-emacs@gnu.org; Sun, 09 Aug 2020 12:36:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Alan Mackenzie Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sun, 09 Aug 2020 16:36:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 41988 X-GNU-PR-Package: emacs Original-Received: via spool by 41988-submit@debbugs.gnu.org id=B41988.159699093712441 (code B ref 41988); Sun, 09 Aug 2020 16:36:02 +0000 Original-Received: (at 41988) by debbugs.gnu.org; 9 Aug 2020 16:35:37 +0000 Original-Received: from localhost ([127.0.0.1]:33319 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1k4oIL-0003Eb-3q for submit@debbugs.gnu.org; Sun, 09 Aug 2020 12:35:37 -0400 Original-Received: from colin.muc.de ([193.149.48.1]:38369 helo=mail.muc.de) by debbugs.gnu.org with smtp (Exim 4.84_2) (envelope-from ) id 1k4oIF-0003EF-2O for 41988@debbugs.gnu.org; Sun, 09 Aug 2020 12:35:35 -0400 Original-Received: (qmail 1733 invoked by uid 3782); 9 Aug 2020 16:35:24 -0000 Original-Received: from acm.muc.de (p2e5d5e8f.dip0.t-ipconnect.de [46.93.94.143]) by localhost.muc.de (tmda-ofmipd) with ESMTP; Sun, 09 Aug 2020 18:35:23 +0200 Original-Received: (qmail 27260 invoked by uid 1000); 9 Aug 2020 16:35:23 -0000 Content-Disposition: inline In-Reply-To: X-Delivery-Agent: TMDA/1.1.12 (Macallan) X-Primary-Address: acm@muc.de 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:184436 Archived-At: Hello, Philipp. On Sun, Aug 09, 2020 at 13:33:53 +0200, Philipp Stephani wrote: > Am Sa., 8. Aug. 2020 um 16:59 Uhr schrieb Alan Mackenzie : > > I must admit, I'm having difficulty understanding this problem. > > On Sat, Aug 08, 2020 at 13:01:50 +0200, Philipp Stephani wrote: > > > Am Mo., 22. Juni 2020 um 01:48 Uhr schrieb Alan Mackenzie : [ .... ] > > > So this is somewhat subtle, so let me try to give some context. The > > > message is merely a symptom of defining a symbol twice (via > > > edebug-make-form-wrapper). That's a problem when using Edebug for > > > coverage instrumentation (in batch mode), as the coverage > > > information is attached to properties of the symbol that Edebug > > > generates/instruments. > > I'm trying to see what, exactly, this problem is. Edebug is defining > > a symbol twice, once for each of two arms of a &or form in the edebug > > spec. The first of these surely does nothing; it will eventually end > > up in the garbage collector. The second will form the function slot > > of the symbol, fulfilling all the Edebug things. What am I missing? > The problem is that Edebug not only generates objects that would later > be garbage-collected (and therefore not observable), but also modifies > observable global state. This starts at > https://git.savannah.gnu.org/cgit/emacs.git/tree/lisp/emacs-lisp/edebug.el?id=55bcb3f7e05c01d86778f1a2b7caccf72124614d#n1418 > and continues for the rest of the edebug-make-form-wrapper function. > In particular, > https://git.savannah.gnu.org/cgit/emacs.git/tree/lisp/emacs-lisp/edebug.el?id=55bcb3f7e05c01d86778f1a2b7caccf72124614d#n1444 > sets the `edebug' symbol property of the symbol being generated. None > of these mutations are undone when backtracking. Ah, I think I see it, now. edebug-form-data contains structures referring to functions, and could well have two entries with the same function name. (I see that at the moment in a file where I instrumented alternately an old version and a new version of a function.) The property list on the symbol then contains a messy combination of details for the two functions. > > > Instrumenting a symbol with two different definitions can lead to > > > very subtle bugs because the frequency vector and the form offset > > > vector are out of sync, .... > > The picture you seem to be painting is of two distinct definitions > > being assigned to the same symbol, and both of them being live. Do > > you have any evidence that this is happening? > Let's say it's rather an incompatible mixture of two definitions. > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=41853 is a symptom of > this. Another piece of evidence is the implementation of > `edebug-make-form-wrapper': that function clearly modifies buffer > contents and symbol properties even in branches that would later be > discarded as part of backtracking. > My (not well evidenced) assumption is that > https://git.savannah.gnu.org/cgit/emacs.git/tree/lisp/emacs-lisp/edebug.el?id=55bcb3f7e05c01d86778f1a2b7caccf72124614d#n1427 > regenerates the offset vector, but there's no regeneration of the > frequency vector, which is the immediate trigger of > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=41853, since now the > frequency and offset vectors might be incompatible with each other. > But I'd also assume the problem runs deeper: edebug-make-form-wrapper > performs multiple mutations, and it's not really clear which of those > are "safe" w.r.t. multiple definitions in not-taken branches. How about, instead of having symbol properties, we institute non-symbol property lists contained in each entry in edebug-form-data? This list could be rapidly searched, with repeated memq, for the pertinent entry. It would mean, however, that all gathered data would be discarded on each fresh instrumentation of a function. Apologies if you've already suggested this and I missed it. > > > .... see e.g. https://debbugs.gnu.org/cgi/bugreport.cgi?bug=41853. > > > Therefore it's important to prevent such duplicate instrumentation, > > > typically by changing the Edebug symbol in some way (appending a unique > > > suffix, etc.). Edebug does this already in many cases (ERT tests, CL > > > methods, ...), but not always. For some more context, see the coverage > > > instrumentation in my Bazel rules for ELisp > > > (https://github.com/phst/rules_elisp). > > > https://github.com/phst/rules_elisp/blob/master/elisp/ert/runner.el > > > contains the ERT and coverage integration. In > > > https://github.com/phst/rules_elisp/blob/0b24aa1660af2f6c668899bdd78aaba383d7ac18/elisp/ert/runner.el#L133-L134 > > > I explicitly check for duplicate instrumentation. It is hard to predict > > > in general whether a specific instance of duplicate instrumentation > > > will lead to bugs like > > > https://debbugs.gnu.org/cgi/bugreport.cgi?bug=41853 or not, thus I'm > > > treating every duplicate instrumentation as a bug. > > What exactly do you mean by "duplicate instrumentation"? If a symbol > > gets defined twice, once for each arm of an &or in the edebug spec, does > > that count as a duplicate instrumentation? > What I mean concretely is evaluating `edebug-make-form-wrapper' (and > therefore, mutating symbol properties and buffer contents) once for > each branch of an &or construct. OK, thanks. How does my above plan, for reinitilising the function's properties at each instrumentation, sound? -- Alan Mackenzie (Nuremberg, Germany).