Subject: 25.0.50; Surprising prefix displayed in echo area when exiting Ediff
From: Eli Zaretskii <[email-masked]>
To: [email-masked], Stefan Monnier <[email-masked]>
Date: Sat, 31 Oct 2015 10:02:46 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Recipe to reproduce:

  emacs -Q
  C-x b foo RET
  C-x b bar RET
  M-x ediff-buffers RET RET RET
  q

After typing 'q' into the Ediff control frame, the prompt displayed in
the minibuffer is this:

  Quit this Ediff session? (y or n)  switch-frame-_

where '_' indicates the cursor position.  That "switch-frame-" prefix
is unexpected, and shouldn't be shown.

I suspect this commit:

  commit 5dc644a6b01e2cf950ff617ab15be4bf1917c38c
  Author: Stefan Monnier <[email-masked]>
  Date:   Tue Sep 1 21:14:18 2015 -0400

      Generalize the prefix-command machinery of C-u

My evidence is that the problem appeared between Sep 1 and Sep 2 (I
have binaries built on both these dates), and the above seems the only
relevant change during that time.

In GNU Emacs 25.0.50.641 (i686-pc-mingw32)
 of 2015-10-31
Repository revision: b059c6b584e964296d425667642650f42972c238
Windowing system distributor 'Microsoft Corp.', version 5.1.2600
Configured using:
 'configure --prefix=/d/usr --enable-checking=yes,glyphs --with-wide-int
 'CFLAGS=-O0 -gdwarf-4 -g3''

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

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

Major mode: Lisp Interaction

Minor modes in effect:
  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:
Checking for load-path shadows...done
Mark set [2 times]
Saved text from "From: [email-masked]"
Auto-saving...
Computing differences between ediff7961OH and ediff796BFO ...
Processing difference regions ... done
Quit this Ediff session? (y or n) y
Computing differences between ediff796OPU and ediff796bZa ...
Processing difference regions ... done
Quit this Ediff session? (y or n) y

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 help-fns help-mode easymenu cl-loaddefs pcase cl-lib mail-prsvr
mail-utils 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 85038 5083)
 (symbols 56 19989 0)
 (miscs 48 36 107)
 (strings 16 15924 5685)
 (string-bytes 1 391583)
 (vectors 16 11294)
 (vector-slots 8 409901 2734)
 (floats 8 129 67)
 (intervals 40 260 63)
 (buffers 856 11))