bug#12641: Backslash in the end of comment lines in C/C++

[Chen Fengyuan]

This bug report will be sent to the Bug-GNU-Emacs mailing list
and the GNU bug tracker at debbugs.gnu.org.  Please check that
the From: line contains a valid email address.  After a delay of up
to one day, you should receive an acknowledgement at that address.

Please write in English if possible, as the Emacs maintainers
usually do not have translators for other languages.

Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug.  If you can, give a recipe
starting from `emacs -Q':

int a=1;
//some comment \
a++;
printf("%d\n",a);
//some comment ??/
a++;
printf("%d\n",a);

a++ is a part of comment, but emacs don't highlight a++ as a comment.
http://stackoverflow.com/questions/2384276/backslash-in-the-end-of-comment-lines-in-c-c


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
For information about debugging Emacs, please read the file
/Applications/Emacs.app/Contents/Resources/etc/DEBUG.


In GNU Emacs 24.2.1 (x86_64-apple-darwin, NS apple-appkit-1038.36)
of 2012-08-27 on bob.porkrind.org
Windowing system distributor `Apple', version 10.3.1187
Configured using:
`configure '--host=x86_64-apple-darwin' '--build=i686-apple-darwin'
'--with-ns' 'build_alias=i686-apple-darwin'
'host_alias=x86_64-apple-darwin' 'CC=gcc -mmacosx-version-min=10.5''

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: nil
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default enable-multibyte-characters: t

Major mode: C++/la

Minor modes in effect:
  erc-list-mode: t
  erc-menu-mode: t
  erc-autojoin-mode: t
  erc-ring-mode: t
  erc-pcomplete-mode: t
  erc-track-mode: t
  erc-track-minor-mode: t
  erc-match-mode: t
  erc-button-mode: t
  erc-fill-mode: t
  erc-stamp-mode: t
  erc-netsplit-mode: t
  shell-dirtrack-mode: t
  keyfreq-autosave-mode: t
  keyfreq-mode: t
  savehist-mode: t
  erc-log-mode: t
  erc-services-mode: t
  erc-networks-mode: t
  erc-irccontrols-mode: t
  erc-noncommands-mode: t
  erc-move-to-prompt-mode: t
  erc-readonly-mode: t
  desktop-save-mode: t
  global-auto-complete-mode: t
  auto-complete-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
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t

Recent input:
r t <tab> <tab> <tab> <return> C-g M-x M-p C-e <tab> 
<tab> - q u <tab> <return> b a c k s l a s h , m <backspace> 
c o m m e n t <return> <help-echo> <help-echo> <down> 
<down> <right> <right> <right> <right> <right> <return> 
<down> <left> <left> <down> <left> <left> SPC <up> 
<up> <up> <down> <return> <return> <return> <right> 
<right> <right> <right> <right> <down> <return> <help-echo> 
<down> <down> <down> <down> <return> <up> <up> <up> 
<up> <up> <down> <down> <down> <down> <down> <down> 
<up> C-c C-o <wheel-down> <double-wheel-down> <triple-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <down-mouse-1> 
<help-echo> <mouse-movement> <drag-mouse-1> <help-echo> 
<wheel-up> <double-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<help-echo> <down> <down> <up> <up> <up> <up> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> 
<up> <up> n C-f C-f C-f <help-echo> <help-echo> <help-echo> 
<down-mouse-1> <mouse-1> <down> <down> <down> <right> 
<right> C-S-e <left> M-w <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
M-< <down> <down> <down> <down> <down> <down> <down> 
<up> <left> <left> <left> <left> <help-echo> <down-mouse-1> 
<mouse-1> <help-echo> <help-echo> C-x b <return> M-x 
M-p M-p <return>

Recent messages:
widget-button-press: Buffer is read-only: #<buffer *Existing Emacs Bugs*>
call-interactively: Buffer is read-only: #<buffer *Existing Emacs Bugs*>
widget-apply-action: Attempt to perform action on inactive widget
byte-code: End of buffer [6 times]
byte-code: Beginning of buffer [17 times]
call-interactively: Buffer is read-only: #<buffer *Existing Emacs Bugs*>
widget-apply-action: Attempt to perform action on inactive widget
Mark set
byte-code: End of buffer [5 times]
Mark set
widget-apply-action: Attempt to perform action on inactive widget

Load-path shadows:
~/gits/elisp/numbers hides ~/.lisp/numbers
~/.lisp/apel-10.8/timezone hides 
/Applications/Emacs.app/Contents/Resources/lisp/timezone
~/.lisp/apel-10.8/env hides /Applications/Emacs.app/Contents/Resources/lisp/env

Features:
(url-cache url-http url-gw url-auth url url-proxy url-privacy url-expand
url-methods url-history url-cookie url-util url-parse url-vars mailcap
shadow sort mail-extr emacsbug message rfc822 mml mml-sec mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mail-utils time-stamp help-mode view
vc-git network-stream starttls erc-menu erc-join erc-ring erc-pcomplete
erc-track erc-match erc-button wid-edit erc-fill erc-stamp erc-netsplit
org-wl org-w3m org-vm org-rmail org-mhe org-mew org-irc org-jsinfo
org-infojs org-html org-info org-gnus org-docview org-bibtex bibtex
org-bbdb cc-mode cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align
cc-engine cc-vars cc-defs auto-complete-autoloads bbdb-autoloads
magit-autoloads paredit-autoloads popup-autoloads
pretty-lambdada-autoloads numbers slime-tramp tramp tramp-compat
auth-source eieio assoc gnus-util mm-util mail-prsvr password-cache
shell tramp-loaddefs org-export-beamer org-latex org-export-latex
org-beamer org-exp ob-exp org-exp-blocks find-func org-agenda footnote
keyfreq dired-sort pretty-lambdada savehist ace-jump-mode paredit ielm
slime-fancy slime-fontifying-fu slime-package-fu slime-references
slime-scratch slime-presentations slime-fuzzy slime-fancy-inspector
slime-c-p-c slime-editing-commands slime-autodoc slime-parse slime-repl
slime hyperspec browse-url erc-view-log erc-log tls erc-services
erc-networks erc-goodies erc erc-backend erc-compat thingatpt pp
org-film org byte-opt warnings bytecomp byte-compile cconv macroexp
ob-emacs-lisp ob-tangle ob-ref ob-lob ob-table org-footnote org-src
ob-comint ob-keys ob ob-eval org-pcomplete pcomplete comint ansi-color
ring org-list org-faces org-compat org-entities org-macs noutline
outline easy-mmode format-spec cal-menu easymenu calendar cal-loaddefs
desktop mule-util advice help-fns advice-preload alist pym static
apel-ver product elscreen server epa-file epa derived epg epg-config
dired-single auto-complete-config auto-complete popup ido cl paren
edmacro kmacro terminal-notifier dired regexp-opt package tabulated-list
time-date tooltip ediff-hook vc-hooks lisp-float-type mwheel ns-win
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 ns multi-tty emacs)