bug#22292: 25.0.50; xref-find-references doesn't find anything for Lisp symbols

[Eli Zaretskii]

From: eliz@HOME-C4E4A596F7.i-did-not-set--mail-host-address--so-tickle-me
--text follows this line--
To reproduce:

  emacs -Q
  C-x C-f lisp/subr.el RET
  M-? executing-kbd-macro RET

The result is disappointing:

  No references found for: executing-kbd-macro

The equivalent command in a C buffer (for a C symbol) does work as
expected.

I'm guessing that something is missing in the Lisp xref back-end that
doesn't let us support this operation.  However, I don't think we can
ship Emacs 25.1 with such an omission.  Lisp is one of the 2 languages
in which Emacs is written, so we ought to support it well.

Can someone please implement the necessary functionality on the
emacs-25 branch?  Bonus points for doing that for a few more popular
languages for which we have support in lisp/progmodes/.

(This came up in the context of rewriting the "Tags Tables" section of
the user manual, where etags.el functionality now takes a back seat to
xref.el.  Part of that is documenting the xref-find-references
command.  But we cannot in good faith advertise a brand-new command
when its support for Lisp is so incomplete.  It doesn't look good.)

This bug will be a release blocker for v25.1.


In GNU Emacs 25.0.50.253 (i686-pc-mingw32)
 of 2016-01-02 built on HOME-C4E4A596F7
Repository revision: 964bea7da5283a6c1ca2d7c6ee8a9d07d4951e69
Windowing system distributor 'Microsoft Corp.', version 5.1.2600
Configured using:
 'configure --prefix=/d/usr --enable-checking=yes,glyphs --with-wide-int
 --with-modules 'CFLAGS=-O0 -gdwarf-4 -g3''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY ACL GNUTLS LIBXML2 ZLIB
TOOLKIT_SCROLL_BARS MODULES

Important settings:
  value of $LANG: ENU
  locale-coding-system: cp1255

Major mode: Emacs-Lisp

Minor modes in effect:
  diff-auto-refine-mode: t
  tooltip-mode: t
  global-eldoc-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
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Mark saved where search started
user-error: No references found for: executing-kbd-macro
Scanning for dabbrevs...done
user-error: No dynamic expansion for ‘xref-find-ref’ found

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr dabbrev emacsbug message dired
format-spec rfc822 mml mml-sec mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util help-fns mail-prsvr mail-utils semantic/symref/grep
grep compile comint ansi-color semantic/symref semantic/util-modes
semantic/util semantic semantic/tag semantic/lex semantic/fw mode-local
find-func cedet vc-bzr vc-src vc-sccs vc-svn vc-cvs vc-rcs thingatpt
xref cl-seq project ring eieio eieio-core cl-macs character-fold
misearch multi-isearch vc vc-dispatcher vc-git diff-mode easy-mmode map
seq byte-opt gv bytecomp byte-compile cconv cl-extra help-mode easymenu
cl-loaddefs pcase cl-lib time-date mule-util tooltip eldoc electric
uniquify ediff-hook vc-hooks lisp-float-type mwheel dos-w32 ls-lisp
disp-table w32-win w32-vars term/common-win tool-bar dnd fontset image
regexp-opt fringe tabulated-list newcomment elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow timer select scroll-bar
mouse jit-lock font-lock syntax facemenu font-core frame cl-generic 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 charscript case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer cl-preloaded nadvice
loaddefs button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote w32notify w32 multi-tty
make-network-process emacs)

Memory information:
((conses 16 126058 6754)
 (symbols 56 23822 0)
 (miscs 48 45 110)
 (strings 16 36488 20905)
 (string-bytes 1 865921)
 (vectors 16 17696)
 (vector-slots 8 539561 4443)
 (floats 8 244 113)
 (intervals 40 648 200)
 (buffers 856 13))