bug#73533: [PATCH] Rewrite speedbar expansion for all descendants

[Morgan Willcock <morgan@ice9.digital>]

Eli Zaretskii <eliz@gnu.org> writes:

> There seems to be still a problem with some files, in that
> speedbar-expand-line-descendants takes a very long time, and if I
> interrupt it with C-g, I see nested DEFUNs, something that shouldn't
> happen, because DEFUNs are never nested.  E.g., try this:
>
>  $ cd /path/to/emacs/src
>  $ ./emacs -Q
>  M-x speedbar RET
>
> At this point you should see all the files in the Emacs src directory.
> Go to androidfns.c and type '['.  After about 10 sec type C-g.  You
> should see nested DEFUns in the Speedbar frame.
>
> Could you please look into this?

This looks like an unrelated issue where the logic to modify the item
hierarchy does not make sense under certain conditions.  It only seems
to trigger when particular limits are met, but the limits can be lowered
for an easier demonstration:

  (require 'speedbar)
  (setq speedbar-tag-regroup-maximum-length 2)
  (setq speedbar-tag-split-minimum-length 2)

  (speedbar-prefix-group-tag-hierarchy
   '(("DEFUN" . 1)
     ("DEFUN" . 5)
     ("DEFUN" . 10)))

  => (("DEFUN" ("DEFUN" . 1) ("DEFUN" . 5) ("DEFUN" . 10)))

i.e. speedbar-prefix-group-tag-hierarchy (which is meant to restructure
the Imenu data to make better use of the available space in the
Speedbar) is generating a new parent item which contains the items that
were meant to be inserted.

It is probably best to open a separate bug report for this because
working out exactly how and why speedbar-prefix-group-tag-hierarchy
applies particular sorting actions will probably take someone a while.

-- 
Morgan Willcock