Subject: bug#40088: 27.0.90; Symbol’s value as variable is void: debugger-outer-match-data

From: Noam Postavsky <[email-masked]>
Date: Sun, 22 Mar 2020 23:17:06 -0400

tags 40088 fixed
close 40088 27.1
quit

Eli Zaretskii <[email-masked]> writes:

> It sounds like a very basic error.  How come we never saw it before?
> Is it just luck?

Like I said, the debug.el code changed in Emacs 27 so that the bug can
be triggered more often.

    The main difference in Emacs 27 is that debug.el calls backtrace--locals
    up front, during setup.  In Emacs 26, it's only called when calling
    backtrace-toggle-locals.

> I'm okay with making the change on the emacs-27 branch, but please put
> some of the description above in the commit log message, including why
> calling default_value etc. avoids the problem (which might not be
> obvious, unless one remembers by heart what Fdefault_value does).

Done and pushed.

[1: 9ab85f087f]: 2020-03-22 23:06:31 -0400
  Fix cl-concatenate (Bug#40180)
  https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=9ab85f087f7db38168dcf07d24f51ecd2c583f8a