bug#18871: 24.4; nxml-mode: DTD edition breaks the file structure

[Vincent Lefevre]

Consider the following XML file:

------------------------------------------------------------------
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE root [
<!ELEMENT root (item)*>
<!ELEMENT item (#PCDATA)>
]>

<root>
<!-- 1234567890 1234567890 1234567890 1234567890 1234567890 -->
</root>
------------------------------------------------------------------

1. Open it with "emacs -Q".
2. Go to line 2 and type C-SPC.
3. Go to line 6 and type C-w to delete the DTD.

The highlighting gets completely wrong. And if I delete the closing
tag </root> (with C-k) and type C-c C-f, I get the error:

  No matching start-tag

In more complex files, slightly editing the DTD gives the same behavior.



In GNU Emacs 24.4.1 (x86_64-pc-linux-gnu, GTK+ Version 3.14.3)
 of 2014-10-25 on trouble, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11601000
System Description:     Debian GNU/Linux unstable (sid)

Configured using:
 `configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 
--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp
 --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/lib --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes
 
--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp
 --with-x=yes --with-x-toolkit=gtk3 --with-toolkit-scroll-bars
 'CFLAGS=-g -O2 -fstack-protector-strong -Wformat
 -Werror=format-security -Wall' CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-z,relro'

Important settings:
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: en_US.UTF-8
  value of $LC_TIME: en_DK
  value of $LANG: POSIX
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  display-time-mode: t
  show-paren-mode: t
  tooltip-mode: t
  mouse-wheel-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
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<escape> x r e p o r t - e m <tab> <return>

Recent messages:
ledger removed but not purged, skipping setup
Loading /etc/emacs/site-start.d/50ledger.el (source)...done
Loading /etc/emacs/site-start.d/50maxima-emacs.el (source)...done
Loading /etc/emacs/site-start.d/50psvn.el (source)...done
Loading /etc/emacs/site-start.d/50python-docutils.el (source)...done
Loading /etc/emacs/site-start.d/50rnc-mode.el (source)...done
Loading /etc/emacs/site-start.d/50w3m-el.el (source)...done
Loading /home/vlefevre/share/emacs/site-lisp/mutteditor.el (source)...done
Loading time...done
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
/usr/share/emacs24/site-lisp/css-mode/css-mode hides 
/usr/share/emacs/site-lisp/css-mode/css-mode
/usr/share/emacs/24.4/site-lisp/debian-startup hides 
/usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs/site-lisp/autoconf/autotest-mode hides 
/usr/share/emacs/site-lisp/autotest-mode
/usr/share/emacs24/site-lisp/cmake-data/cmake-mode hides 
/usr/share/emacs/site-lisp/cmake-mode
/usr/share/emacs24/site-lisp/flim/hex-util hides 
/usr/share/emacs/24.4/lisp/hex-util
/usr/share/emacs24/site-lisp/flim/md4 hides /usr/share/emacs/24.4/lisp/md4
/usr/share/emacs24/site-lisp/html-helper-mode/tempo hides 
/usr/share/emacs/24.4/lisp/tempo
/usr/share/emacs/site-lisp/rst hides /usr/share/emacs/24.4/lisp/textmodes/rst
/usr/share/emacs24/site-lisp/dictionaries-common/ispell hides 
/usr/share/emacs/24.4/lisp/textmodes/ispell
/usr/share/emacs24/site-lisp/dictionaries-common/flyspell hides 
/usr/share/emacs/24.4/lisp/textmodes/flyspell
/usr/share/emacs24/site-lisp/css-mode/css-mode hides 
/usr/share/emacs/24.4/lisp/textmodes/css-mode
/usr/share/emacs24/site-lisp/flim/hmac-md5 hides 
/usr/share/emacs/24.4/lisp/net/hmac-md5
/usr/share/emacs24/site-lisp/flim/sasl-ntlm hides 
/usr/share/emacs/24.4/lisp/net/sasl-ntlm
/usr/share/emacs24/site-lisp/flim/ntlm hides /usr/share/emacs/24.4/lisp/net/ntlm
/usr/share/emacs24/site-lisp/flim/sasl hides /usr/share/emacs/24.4/lisp/net/sasl
/usr/share/emacs24/site-lisp/flim/sasl-cram hides 
/usr/share/emacs/24.4/lisp/net/sasl-cram
/usr/share/emacs24/site-lisp/flim/sasl-digest hides 
/usr/share/emacs/24.4/lisp/net/sasl-digest
/usr/share/emacs24/site-lisp/flim/hmac-def hides 
/usr/share/emacs/24.4/lisp/net/hmac-def
/usr/share/emacs24/site-lisp/latex-cjk-thai/thai-word hides 
/usr/share/emacs/24.4/lisp/language/thai-word
/usr/share/emacs24/site-lisp/html-helper-mode/tempo hides 
/usr/share/emacs/site-lisp/html-helper-mode/tempo
/usr/share/emacs24/site-lisp/html-helper-mode/visual-basic-mode hides 
/usr/share/emacs/site-lisp/html-helper-mode/visual-basic-mode
/usr/share/emacs24/site-lisp/html-helper-mode/hhm-config hides 
/usr/share/emacs/site-lisp/html-helper-mode/hhm-config
/usr/share/emacs24/site-lisp/html-helper-mode/html-helper-mode hides 
/usr/share/emacs/site-lisp/html-helper-mode/html-helper-mode

Features:
(shadow sort gnus-util mail-extr warnings emacsbug message format-spec
rfc822 mml easymenu 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 time cus-start
cus-load paren cc-styles cc-align cc-engine cc-vars cc-defs w3m-load
time-date tooltip electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list newcomment lisp-mode prog-mode register page menu-bar
rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax
facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak
czech european ethiopic indian cyrillic chinese case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer 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 make-network-process dbusbind gfilenotify dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty emacs)

Memory information:
((conses 16 90937 6945)
 (symbols 48 20074 0)
 (miscs 40 96 93)
 (strings 32 15093 5150)
 (string-bytes 1 437464)
 (vectors 16 9916)
 (vector-slots 8 393379 6312)
 (floats 8 69 257)
 (intervals 56 232 0)
 (buffers 960 12)
 (heap 1024 42678 1099))