bug#13174: 24.1; comment-region incorrectly handling XML comments already present

bug#13174: 24.1; comment-region incorrectly handling XML comments already present

[Louis-Dominique Dubeau]

1. Execute:

$ emacs -Q

2. M-x nxml-mode.

3. Emtpy the buffer.

4. Enter the following text:

<!-- Blah -->

5. Select that text and issue M-x comment-region.

The text becomes: 

<!-- <\!-- Blah -\-> -->

which is invalid XML. Josse van der Plaat has a solution at:

http://emacswiki.org/emacs/mz-comment-fix.el

Using his solution yields:
 
<!-- <!-\- Blah -\-> -->

which is is valid XML.

This is a bug which has been circulating the internet since at least
2004. James Clark reported in 2004 having communicated with the
maintainer of newcomment.el but apparently nothing happened. See this
message:

http://tech.groups.yahoo.com/group/emacs-nxml-mode/message/661

Please integrate Josse van der Plaat's solution to emacs. Thank you.

In GNU Emacs 24.1.1 (x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2012-09-22 on batsu, modified by Debian
Windowing system distributor `The X.Org Foundation', version
11.0.11300000
Configured using:
 `configure '--build' 'x86_64-linux-gnu' '--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/24.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.1/site-lisp:/usr/share/emacs/site-lisp'
 '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes'
 '--with-x-toolkit=lucid' '--with-toolkit-scroll-bars' '--without-gconf'
 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector
 --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall -O2'
 'CPPFLAGS=-D_FORTIFY_SOURCE=2''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: nXML

Minor modes in effect:
  tooltip-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 input:
M-x n x m l - m o <tab> <return> C-SPC <C-up> C-w <down> 
<down> < ! - - SPC B l a h SPC - - > <return> <up> 
C-SPC <down> M-x <up> <up> <up> <down> C-k c o m m 
e n <tab> - <backspace> r <tab> <return> <help-echo> 
<help-echo> M-x <up> <down> e m a c <tab> b u <tab> 
<tab> <backspace> <tab> <backspace> <tab> <M-backspace> 
<M-backspace> <M-backspace> <M-backspace> r e e <tab> 
<backspace> p <tab> o <tab> r <tab> <return>

Recent messages:
Error during redisplay: (error "Invalid search bound (wrong side of
point)")
Mark set
Illegal char in prolog
byte-code: End of buffer [2 times]
No document element [8 times]
Mark activated
goto-history-element: Beginning of history; no preceding item [2 times]
kill-line: End of buffer
No document element
Making completion list... [2 times]

Load-path shadows:
/usr/share/emacs/24.1/site-lisp/debian-startup
hides /usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs/24.1/site-lisp/dictionaries-common/flyspell
hides /usr/share/emacs/24.1/lisp/textmodes/flyspell
/usr/share/emacs/24.1/site-lisp/dictionaries-common/ispell
hides /usr/share/emacs/24.1/lisp/textmodes/ispell

Features:
(shadow sort gnus-util mail-extr emacsbug message 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 help-mode view newcomment nxml-uchnm rng-xsd
xsd-regexp rng-cmpct regexp-opt rng-nxml rng-valid rng-loc rng-uri
rng-parse nxml-parse rng-match rng-dt rng-util rng-pttrn nxml-ns
easymenu nxml-mode nxml-outln nxml-rap nxml-util nxml-glyph nxml-enc
xmltok time-date tooltip ediff-hook vc-hooks lisp-float-type mwheel
x-win x-dnd tool-bar dnd fontset image fringe lisp-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 loaddefs
button faces cus-face files text-properties overlay sha1 md5 base64
format env code-pages mule custom widget hashtable-print-readable
backquote make-network-process dbusbind dynamic-setting
system-font-setting font-render-setting x-toolkit x multi-tty emacs)

bug#13174: 24.1; comment-region incorrectly handling XML comments already present

[Lars Ingebrigtsen]

Louis-Dominique Dubeau <ldd@lddubeau.com> writes:

> 1. Execute:
>
> $ emacs -Q
>
> 2. M-x nxml-mode.
>
> 3. Emtpy the buffer.
>
> 4. Enter the following text:
>
> <!-- Blah -->
>
> 5. Select that text and issue M-x comment-region.
>
> The text becomes: 
>
> <!-- <\!-- Blah -\-> -->
>
> which is invalid XML. Josse van der Plaat has a solution at:
>
> http://emacswiki.org/emacs/mz-comment-fix.el
>
> Using his solution yields:
>
> <!-- <!-\- Blah -\-> -->
>
> which is is valid XML.

(I'm going through old bug reports that have unfortunately gotten no
responses yet.)

I tried your recipe in Emacs 27, and I got:

<!-- <!-\- Blah -\-> -->

So I'm going to go ahead and guess that this bug has been fixed at some
point in the years since the report was filed, and I'm closing this bug
report.  If you're still seeing this, please reopen.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no