bug#22026: 25.0.50; M-. in a C Mode buffer signals an error

[Eli Zaretskii]

 emacs -Q
 C-x C-f src/lread.c
 C-u 58425 M-x goto-char
 M-.

This signals an error:

  No applicable method for %S: xref-backend-definitions, etags, "readevalloop"

(The goto-char command goes to the call to readevalloop inside
Feval_buffer.)

The problem goes away if I invoke "M-x visit-tags-table" manually, and
then invoke M-.
 



In GNU Emacs 25.0.50.70 (i686-pc-mingw32)
 of 2015-11-27
Repository revision: a41cb8c4d3af3f7e542a7bdf79858385a3274d4d
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: C/l

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
  abbrev-mode: t

Recent messages:
Type C-x 1 to delete the help window, C-M-v to scroll help.
Mark set
cl-no-applicable-method: No applicable method for %S: xref-backend-definitions, 
etags, "readevalloop"
Making completion list... [2 times]
Starting a new list of tags tables
Quit
user-error: No mark set in this buffer
Quit

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr 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 mail-prsvr mail-utils pulse etags thingatpt xref cl-seq project
ring eieio eieio-core cl-macs vc vc-dispatcher vc-git diff-mode
easy-mmode map seq byte-opt gv bytecomp byte-compile cconv cc-mode
cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars
cc-defs find-func cl-extra help-fns 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 127542 8832)
 (symbols 56 23856 0)
 (miscs 48 46 140)
 (strings 16 27999 6462)
 (string-bytes 1 852935)
 (vectors 16 17304)
 (vector-slots 8 480827 3997)
 (floats 8 226 295)
 (intervals 40 1329 13)
 (buffers 856 18))