bug#73889: 31.0.50; speedbar-expand-line-descendants produces nested "DEFUN" structures

bug#73889: 31.0.50; speedbar-expand-line-descendants produces nested "DEFUN" structures

[Eli Zaretskii]

To reproduce:

 $ cd /path/to/emacs/src
 $ ./emacs -Q
 M-x speedbar RET

At this point the Speedbar frame shows all the files in the Emacs src
directory.  Go to androidfns.c and type '['.  After about 10 sec type
C-g.  The nested DEFUNs should now be visible in the Speedbar frame.


In GNU Emacs 31.0.50 (build 314, i686-pc-mingw32) of 2024-10-19 built on
 ELIZ-PC
Windowing system distributor 'Microsoft Corp.', version 10.0.22631
System Description: Microsoft Windows 10 Enterprise (v10.0.2009.22631.4317)

Configured using:
 'configure -C --prefix=/d/usr --with-wide-int
 --without-native-compilation --enable-checking=yes,glyphs 'CFLAGS=-O0
 -gdwarf-4 -g3''

Configured features:
ACL GIF GMP GNUTLS HARFBUZZ JPEG LCMS2 LIBXML2 MODULES NOTIFY W32NOTIFY
PDUMPER PNG RSVG SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS
TREE_SITTER WEBP XPM ZLIB

Important settings:
  value of $LANG: ENU
  locale-coding-system: cp1252

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util text-property-search time-date subr-x mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
cl-loaddefs cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils rmc iso-transl tooltip cconv eldoc paren electric
uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
touch-screen dos-w32 ls-lisp disp-table term/w32-win w32-win w32-vars
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode lisp-mode prog-mode register
page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors
frame minibuffer nadvice seq simple cl-generic indonesian philippine
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads w32notify w32 lcms2 multi-tty move-toolbar make-network-process
emacs)

Memory information:
((conses 16 45406 13116) (symbols 48 6526 0) (strings 16 16091 3250)
 (string-bytes 1 331929) (vectors 16 9402)
 (vector-slots 8 110841 9335) (floats 8 23 6) (intervals 40 299 90)
 (buffers 896 10))

bug#73889: 31.0.50; speedbar-expand-line-descendants produces nested "DEFUN" structures

[Morgan Willcock]

Here is an example to demonstrate the specifics of the problem:

  printf "DEFUN () {};\nDEFUN () {};\nDEFUN () {};\n" >/tmp/test.c

  emacs -Q \
        --eval "(require 'speedbar)" \
        --eval "(setq speedbar-tag-regroup-maximum-length 2)" \
        --eval "(setq speedbar-tag-split-minimum-length 2)" \
        --eval "(find-file \"/tmp/test.c\")" \
        --eval "(speedbar)"

Expanding the "test.c" item in the Speedbar will now show a single
"DEFUN" item, but expanding that "DEFUN" item will just insert an
additional "DEFUN" item that also needs to be expanded.  This behaviour
will repeat infinitely.

The problem appears to originate from when the item hierarchy is
modified by speedbar-prefix-group-tag-hierarchy, where exceeding the
limits for both speedbar-tag-regroup-maximum-length and
speedbar-tag-split-minimum-length will return all items with an
additional parent item:

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

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

-- 
Morgan Willcock