all messages for Emacs-related lists mirrored at yhetil.org
 help / color / mirror / code / Atom feed
From: Alan Mackenzie <acm@muc.de>
To: emacs-devel@gnu.org
Subject: Early backtrace.
Date: Mon, 10 Jan 2022 20:34:08 +0000	[thread overview]
Message-ID: <YdyYQIzQz5DDMFG7@ACM> (raw)

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).



             reply	other threads:[~2022-01-10 20:34 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-10 20:34 Alan Mackenzie [this message]
2022-01-10 21:54 ` Early backtrace Stefan Monnier
2022-01-11 11:36   ` Alan Mackenzie
2022-01-11 14:47     ` Stefan Monnier
2022-01-30 11:07       ` [PATCH]: " Alan Mackenzie
2022-01-30 16:31         ` Stefan Monnier
2022-01-31 14:04           ` Stefan Monnier
2022-02-01 19:14           ` Alan Mackenzie
2022-02-02  3:36             ` Stefan Monnier
2022-02-02 20:38               ` Alan Mackenzie
2022-02-02 20:59                 ` Stefan Monnier
2022-02-03  8:38                   ` Eli Zaretskii
2022-02-03 21:35                     ` Alan Mackenzie
2022-02-04  7:24                       ` Eli Zaretskii
2022-02-04 21:01                         ` Alan Mackenzie
2022-02-05  7:12                           ` Eli Zaretskii
2022-02-05 10:48                             ` Alan Mackenzie
2022-02-04 13:31                     ` Stefan Monnier
2022-02-04 14:02                       ` Eli Zaretskii
2022-01-31  9:30         ` Philipp Stephani
2022-01-31 12:42           ` Eli Zaretskii
2022-01-31 16:54             ` Alan Mackenzie
2022-01-31 17:24               ` Alan Mackenzie

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YdyYQIzQz5DDMFG7@ACM \
    --to=acm@muc.de \
    --cc=emacs-devel@gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this external index

	https://git.savannah.gnu.org/cgit/emacs.git
	https://git.savannah.gnu.org/cgit/emacs/org-mode.git

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.