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: Early backtrace. Date: Mon, 10 Jan 2022 20:34:08 +0000 Message-ID: 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="7882"; mail-complaints-to="usenet@ciao.gmane.io" To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Jan 10 21:35:51 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 1n71OQ-0001qu-TH for ged-emacs-devel@m.gmane-mx.org; Mon, 10 Jan 2022 21:35:50 +0100 Original-Received: from localhost ([::1]:49408 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n71OP-0002dD-Cr for ged-emacs-devel@m.gmane-mx.org; Mon, 10 Jan 2022 15:35:49 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:34492) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n71Mr-0001ud-JA for emacs-devel@gnu.org; Mon, 10 Jan 2022 15:34:13 -0500 Original-Received: from colin.muc.de ([193.149.48.1]:23960 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.90_1) (envelope-from ) id 1n71Mp-0008Pq-Hp for emacs-devel@gnu.org; Mon, 10 Jan 2022 15:34:13 -0500 Original-Received: (qmail 95572 invoked by uid 3782); 10 Jan 2022 20:34:09 -0000 Original-Received: from acm.muc.de (p4fe15a8e.dip0.t-ipconnect.de [79.225.90.142]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Mon, 10 Jan 2022 21:34:09 +0100 Original-Received: (qmail 4338 invoked by uid 1000); 10 Jan 2022 20:34:08 -0000 Content-Disposition: inline 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 autolearn=ham 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:284552 Archived-At: Hello, Emacs. In the course of debugging a recent bug, I found myself needing to get a Lisp backtrace. This was early on in the bootstrap process, where the standard backtrace.el cannot work, since it requires several files.el which are only loaded later. So I came up with the following, which has no Lisp dependencies. That is, absolutely none. I have used it as the first Lisp file loaded, immediately before byte-run.el. So, how about including this file in Emacs, amending eval.c to use it if backtrace.el isn't yet avaiable? Comments and criticism are welcome. lisp/emacs-lisp/early-debug.el: ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; (defalias 'early-backtrace #'(lambda () "Print a trace of Lisp function calls currently active. The output stream used is the value of `standard-output'. This is a simplified version of the standard `backtrace' function, intended for use in debugging the early parts of the build process." (princ "\n") (mapbacktrace #'(lambda (evald func args _flags) (let ((args args)) (if evald (progn (princ " ") (prin1 func) (princ " (") (while args (prin1 (car args)) (setq args (cdr args)) (if args (princ " "))) (princ ")\n")) (while args (princ " ") (prin1 (car args)) (princ "\n") (setq args (cdr args))))))))) (defalias 'early-debug #'(lambda (&rest args) "Print a trace of Lisp function calls currently active. The output stream used is the value of `standard-output'. There should be two ARGS, the symbol `error' and a cons of the error symbol and its data. This is a simplified version of `debug', intended for use in debugging the early parts of the build process." (princ "\nError: ") (prin1 (car (car (cdr args)))) ; The error symbol. (princ " ") (prin1 (cdr (car (cdr args)))) ; The error data. (early-backtrace))) (setq debugger #'early-debug) ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; -- Alan Mackenzie (Nuremberg, Germany).