* bug#56201: Backtrace fails to appear in an error situation.
@ 2022-06-24 17:42 Alan Mackenzie
2022-06-24 18:22 ` Andreas Schwab
2022-06-24 18:23 ` Lars Ingebrigtsen
0 siblings, 2 replies; 3+ messages in thread
From: Alan Mackenzie @ 2022-06-24 17:42 UTC (permalink / raw)
To: 56201
Hello, Emacs.
(i) With the master branch, start Emacs (-Q not needed).
(ii) Visit a non-empty file in a buffer.
(iii) M-s o <regexp that will generate matches>.
(iv) C-x o to move to the *Occur* buffer.
(v) Move point to somewhere in the displayed matches.
(vi) C-x C-q to swith off read-onliness.
(vii) C-j, an attempt to insert a newline.
This produces the error message "Text is read-only". This is probably a
bug, but is minor compared to what follows:
(viii) M-: (setq debug-on-error t) RET.
(ix) C-j.
This ought to produce a backtrace, but doesn't. It merely repeats the
error message "Text is read-only". This is a major bug; how can one
solve minor bugs if attempts to get diagnostic information are blocked?
It would appear a frivolous condition-case is discarding the backtrace
here. This appears to happen with lots of error messages. This is not
a Good Thing.
--
Alan Mackenzie (Nuremberg, Germany).
^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#56201: Backtrace fails to appear in an error situation.
2022-06-24 17:42 bug#56201: Backtrace fails to appear in an error situation Alan Mackenzie
@ 2022-06-24 18:22 ` Andreas Schwab
2022-06-24 18:23 ` Lars Ingebrigtsen
1 sibling, 0 replies; 3+ messages in thread
From: Andreas Schwab @ 2022-06-24 18:22 UTC (permalink / raw)
To: Alan Mackenzie; +Cc: 56201
See debug-ignored-errors.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#56201: Backtrace fails to appear in an error situation.
2022-06-24 17:42 bug#56201: Backtrace fails to appear in an error situation Alan Mackenzie
2022-06-24 18:22 ` Andreas Schwab
@ 2022-06-24 18:23 ` Lars Ingebrigtsen
1 sibling, 0 replies; 3+ messages in thread
From: Lars Ingebrigtsen @ 2022-06-24 18:23 UTC (permalink / raw)
To: Alan Mackenzie; +Cc: 56201
Alan Mackenzie <acm@muc.de> writes:
> This ought to produce a backtrace, but doesn't. It merely repeats the
> error message "Text is read-only". This is a major bug; how can one
> solve minor bugs if attempts to get diagnostic information are blocked?
There's a lot of error conditions that are "normal" and handled by the
code, and `debug-on-error' doesn't help you with that. You have to set
`debug-on-signal' to get a backtrace from those.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-06-24 17:42 bug#56201: Backtrace fails to appear in an error situation Alan Mackenzie
2022-06-24 18:22 ` Andreas Schwab
2022-06-24 18:23 ` Lars Ingebrigtsen
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