bug#66683: 30.0.50; xref-find-references returns duplicates

[Petteri Hintsanen]

[This is a bug report from an old issue discussed in
help-gnu-emacs@gnu.org (dated 19 Dec 2022, Message-ID
<7ac4ca06-cbbb-1c8d-0f59-2ccd5d3232f2@iki.fi>).  Dmitry Gutov asked me
to file a bug, which I unfortunately forgot to do that time.  Hence
filing now.]

I discovered a somewhat peculiar case where xref-find-references returns
duplicate references for elisp symbols.

Recipe:

1. Create a file ~/foo/bar/bar.el with contents:

  (defun bar-f ())

  (defun bar-g ()
    (bar-f))

  (provide 'bar)

2. Create a git repo in ~/foo/bar and commit bar.el.  This is just to
set up a project that Emacs can recognize.

3. Start emacs -Q and eval

  (add-to-list 'load-path "~/foo")
  (add-to-list 'load-path "~/foo/bar")
  (require 'bar)

4. C-x C-f ~/foo/bar/bar.el

5. M-x xref-find-references RET bar-f RET

On my machine I get

  bar.el
  1: (defun bar-f ())
  4:   (bar-f))
  1: (defun bar-f ())
  4:   (bar-f))

i.e. references are duplicated.  The issue seems to be in load-path: if
I remove (add-to-list 'load-path "~/foo") from step (3) above, then I
don't see any duplicates.



In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 2.24.33, cairo version 1.16.0) of 2023-10-22 built on romeo
Repository revision: ae337884107c4d5f66aaceef0e8b548565317412
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101007
System Description: Debian GNU/Linux 12 (bookworm)

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG JSON
LCMS2 LIBOTF LIBSELINUX LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG
SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP
X11 XDBE XIM XINPUT2 XPM GTK2 ZLIB

Important settings:
  value of $LC_MESSAGES: en_US.UTF-8
  value of $LANG: fi_FI.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  display-fill-column-indicator-mode: t
  bug-reference-prog-mode: t
  jinx-mode: t
  winner-mode: t
  savehist-mode: t
  minibuffer-electric-default-mode: t
  display-time-mode: t
  emms-playing-time-display-mode: t
  emms-playing-time-mode: t
  desktop-save-mode: t
  cwm-mode: t
  windmove-mode: t
  override-global-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  minibuffer-regexp-mode: t
  column-number-mode: t
  line-number-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  hs-minor-mode: t

Load-path shadows:
/home/phintsan/.emacs.d/elpa/transient-0.4.3/transient hides 
/home/phintsan/src/emacs/lisp/transient

Features:
(shadow mail-extr emacsbug message yank-media puny rfc822 mml mml-sec
epa derived epg rfc6068 epg-config gnus-util text-property-search
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils hideshow display-fill-column-indicator bug-reference jinx
compat ph-simple-theme rx winner ring savehist minibuf-eldef time
emms-mpris pcase dbus emms-librefm-stream xml emms-librefm-scrobbler
emms-playlist-limit emms-i18n emms-history emms-score emms-stream-info
emms-metaplaylist-mode emms-bookmarks emms-cue emms-mode-line-icon
emms-browser sort emms-volume emms-volume-sndioctl emms-volume-mixerctl
emms-volume-pulse emms-volume-amixer emms-playlist-sort emms-last-played
emms-player-xine emms-player-mpd tq emms-lyrics emms-url time-date
emms-streams emms-show-all emms-tag-editor format-spec emms-tag-tracktag
emms-mark emms-mode-line emms-cache emms-info-native
emms-info-native-spc emms-info-native-mp3 emms-info-native-ogg
emms-info-native-opus emms-info-native-flac emms-info-native-vorbis
bindat emms-info-exiftool emms-info-tinytag emms-info-metaflac
emms-info-opusinfo emms-info-ogginfo emms-info-mp3info
emms-playlist-mode emms-player-vlc emms-player-mpv emms-playing-time
emms-info emms-later-do emms-player-mplayer emms-player-simple
emms-source-playlist emms-source-file thingatpt locate dired
dired-loaddefs emms-setup emms emms-compat desktop frameset cwm-mode
windmove edmacro kmacro cl-extra help-mode use-package-bind-key bind-key
easy-mmode finder-inf use-package-core cus-edit pp cus-load icons
wid-edit ack-autoloads jinx-autoloads perl-doc-autoloads
transient-autoloads with-editor-autoloads info compat-autoloads package
browse-url url url-proxy url-privacy url-expand url-methods url-history
url-cookie generate-lisp-file url-domsuf url-util mailcap url-handlers
url-parse auth-source cl-seq eieio eieio-core cl-macs password-cache
json subr-x map byte-opt gv bytecomp byte-compile url-vars cl-loaddefs
cl-lib rmc iso-transl tooltip cconv eldoc paren electric uniquify
ediff-hook vc-hooks lisp-float-type elisp-mode mwheel term/x-win x-win
term/common-win x-dnd touch-screen 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 dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting cairo gtk x-toolkit xinput2 x multi-tty move-toolbar
make-network-process emacs)

Memory information:
((conses 16 274554 22405) (symbols 48 13707 0) (strings 32 99822 3656)
 (string-bytes 1 2414869) (vectors 16 29913)
 (vector-slots 8 1123232 231495) (floats 8 86 55) (intervals 56 853 0)
 (buffers 992 10))