bug#23127: 25.0.92; Assertion failure when editing history in query-replace in cc-mode

[Richard Copley]

In cc-mode, while doing query-replace, edit a previous replacement in
the minibuffer, and insert characters after the " → " separator. The
subsequent emacs-lisp chokes on the text properties of the resulting
string, with an assertion failure.

Recipe starting from 'emacs -Q':

M-x c-mode RET
M-<
C-% a RET b RET !
M-<
C-% M-p C-e <backspace> c RET

==> error "cl--assertion-failed: Assertion failed: (not
(text-property-any (1+ split-pos) length (quote separator) t string))"

The callstack looks like this (except that here I've replaced a NUL with "^@"):

Debugger entered: ((cl-assertion-failed (not (text-property-any (1+
split-pos) length (quote separator) t string)) nil))
  cl--assertion-failed((not (text-property-any (1+ split-pos) length
(quote separator) t string)))
  query-replace--split-string(#("a^@c" 1 2 (display #(" → " 0 3 (face
minibuffer-prompt)) separator t) 2 3 (separator t)))
  query-replace-read-from("Query replace" nil)
  query-replace-read-args("Query replace" nil)
  (let ((common (query-replace-read-args (concat "Query replace" (if
current-prefix-arg (if (eq current-prefix-arg ...) " backward" "
word") "") (if (use-region-p) " in region" "")) nil))) (list (nth 0
common) (nth 1 common) (nth 2 common) (if (use-region-p)
(region-beginning)) (if (use-region-p) (region-end)) (nth 3 common)
(if (use-region-p) (region-noncontiguous-p))))
  call-interactively(query-replace nil nil)
  command-execute(query-replace)

As you can see, the "c" inherited the separator property, and
query-replace--split-string choked on that.
It doesn't happen in all modes. It does happen in c-mode and c++-mode.

In GNU Emacs 25.0.92.1 (x86_64-w64-mingw32)
 of 2016-03-21 built on MACHINE
Repository revision: 76ef52267cf887e3e1aa6d25b3b16dd0601dd459
Windowing system distributor 'Microsoft Corp.', version 10.0.10586
Configured using:
 'configure --prefix /c/emacs/emacs-20160321-102640
 --without-imagemagick --disable-dependency-tracking
 --enable-locallisppath=%emacs_dir%/../site-lisp 'CFLAGS=-Og -g -ggdb''

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

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

Major mode: C++/l

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
  abbrev-mode: t

Recent messages:
Mark set
cl--assertion-failed: Assertion failed: (not (text-property-any (1+
split-pos) length (quote separator) t string))

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired format-spec rfc822 mml
mml-sec password-cache epg epg-config gnus-util 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
thingatpt cl-extra help-mode cc-mode cc-fonts easymenu cc-guess cc-menus
cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs cl-loaddefs pcase
cl-lib kmacro 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 dbusbind w32 multi-tty
make-network-process emacs)

Memory information:
((conses 16 110212 13535)
 (symbols 56 21829 0)
 (miscs 48 49 129)
 (strings 32 21738 3341)
 (string-bytes 1 713085)
 (vectors 16 15026)
 (vector-slots 8 455559 3738)
 (floats 8 164 97)
 (intervals 56 275 18)
 (buffers 976 12))