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Re: Why is it so difficult to get a Lisp backtrace?
From: |
Alan Mackenzie |
Subject: |
Re: Why is it so difficult to get a Lisp backtrace? |
Date: |
Sat, 25 Jun 2022 15:59:52 +0000 |
Hello, Lars.
On Sat, Jun 25, 2022 at 17:35:02 +0200, Lars Ingebrigtsen wrote:
> Alan Mackenzie <acm@muc.de> writes:
> >> This third group of users is poorly catered for by the current
> >> collection of mechanisms. See also bug #56201, with thanks to
> >> Andreas and Lars who helped me get to the bottom of it. To be
> >> reasonably sure of getting a backtrace, it seems one needs to do
> >> all of the following:
> >> (i) (setq debug-on-error t).
> >> (ii) (setq debug-on-signal t).
> >> (iii) Bind debug-ignored-errors to nil.
> >> (iv) Pray.
> You probably also need to ensure that inhibit-redisplay is nil at the
> point of the error, I think? (At least I vaguely recall having to
> remove some of those bindings to get a backtrace...)
For example, by testing a flag in the backtrace function, and binding
inhibit-redisplay to nil if that flag is set. This could get quite
complicate quite quickly.
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.
> > I mean something like the following, which to a first approximation,
> > works. To use it, do M-x debug-next-command and the execute the
> > command expected to give errors:
> I like it, but it may not be useful in all contexts -- errors are used
> as a programming mechanism here and there (i.e., throwing an error
> symbol to be caught by the caller), and you'll get backtraces from
> these non-error errors, too, unfortunately.
As I suggested in my reply to Stefan, maybe a C-u argument to the
function could be used to exclude (or include) debug-on-signal from the
mix. Or something like that.
> --
> (domestic pets only, the antidote for overdose, milk.)
> bloggy blog: http://lars.ingebrigtsen.no
--
Alan Mackenzie (Nuremberg, Germany).
- Why is it so difficult to get a Lisp backtrace?, Alan Mackenzie, 2022/06/25
- Re: Why is it so difficult to get a Lisp backtrace?, Alan Mackenzie, 2022/06/25
- Re: Why is it so difficult to get a Lisp backtrace?, Lars Ingebrigtsen, 2022/06/25
- Re: Why is it so difficult to get a Lisp backtrace?,
Alan Mackenzie <=
- Re: Why is it so difficult to get a Lisp backtrace?, Eli Zaretskii, 2022/06/25
- Re: Why is it so difficult to get a Lisp backtrace?, Alan Mackenzie, 2022/06/25
- Re: Why is it so difficult to get a Lisp backtrace?, Eli Zaretskii, 2022/06/26
- Fontification error backtrace [Was: Why is it so difficult to get a Lisp backtrace?], Alan Mackenzie, 2022/06/27
- Re: Fontification error backtrace [Was: Why is it so difficult to get a Lisp backtrace?], Lars Ingebrigtsen, 2022/06/28
- Re: Fontification error backtrace [Was: Why is it so difficult to get a Lisp backtrace?], Eli Zaretskii, 2022/06/28
- Re: Fontification error backtrace [Was: Why is it so difficult to get a Lisp backtrace?], Alan Mackenzie, 2022/06/28
- Re: Fontification error backtrace [Was: Why is it so difficult to get a Lisp backtrace?], Eli Zaretskii, 2022/06/28
- Re: Fontification error backtrace [Was: Why is it so difficult to get a Lisp backtrace?], Alan Mackenzie, 2022/06/28
- Re: Fontification error backtrace [Was: Why is it so difficult to get a Lisp backtrace?], Eli Zaretskii, 2022/06/29