GNU bug report logs - #2436
open-paren-in-column-0-is-defun-start and cc-mode

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Tom Tromey <tromey <at> redhat.com>
To: bug-gnu-emacs <at> gnu.org
Subject: cc mode font-locking -vs- multi-line strings
Date: Sun, 22 Feb 2009 11:28:07 -0700

[Message part 1 (text/plain, inline)]

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the bug-gnu-emacs <at> gnu.org mailing list,
and to the gnu.emacs.bug news group.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:


Save the attached file as "infcmd.c".  (It comes from GNU gdb.)
Run emacs -q
Visit infcmd.c
Use M-> to go to the end of the buffer.
Notice that the font-locking is incorrect.

For me, the code at the end of the buffer is fontified as a string,
whereas it is actually a mix of strings and code.  The badness starts
at line 2594.

I can work around the problem by removing a character (say, at the
start of line 2593) and then undoing.

FWIW, I checked out CVS Emacs and built it, and it exhibits this same bug.

[infcmd.c (text/plain, attachment)]

[Message part 3 (text/plain, inline)]

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'.
If you would like to further debug the crash, please read the file
/usr/share/emacs/22.2/etc/DEBUG for instructions.


In GNU Emacs 22.2.1 (i386-redhat-linux-gnu, GTK+ Version 2.12.9)
 of 2008-05-23 on xenbuilder4.fedora.phx.redhat.com
Windowing system distributor `The X.Org Foundation', version 11.0.10500000
configured using `configure  '--build=i386-redhat-linux-gnu' '--host=i386-redhat-linux-gnu' '--target=i386-redhat-linux-gnu' '--program-prefix=' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib' '--libexecdir=/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/usr/com' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--with-x-toolkit=gtk' '--with-sound' '--with-toolkit-scroll-bars' 'build_alias=i386-redhat-linux-gnu' 'host_alias=i386-redhat-linux-gnu' 'target_alias=i386-redhat-linux-gnu' 'CFLAGS=-DMAIL_USE_LOCKF -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables''

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
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Major mode: Group

Minor modes in effect:
  gnus-agent-mode: t
  compilation-in-progress: (gid)
  shell-dirtrack-mode: t
  gnus-undo-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
  erc-spelling-mode: t
  erc-truncate-mode: t
  erc-status-mode: t
  erc-services-mode: t
  erc-irccontrols-mode: t
  erc-noncommands-mode: t
  erc-readonly-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
SPC p r a c t i c e . C-p C-k M-q C-c C-c C-p M S-SPC 
M S-SPC q s C-u C-n SPC M-> Q y s C-z o M-v M-v M-v 
C-v C-v C-v M-> <switch-frame> <switch-frame> <f10> 
<f10> C-z o C-l C-u C-n C-u C-n SPC E q n n SPC 5 0 
<return> M-> q SPC M-> C-u C-p C-u C-p C-u C-u E q 
C-l C-u C-n C-u C-n C-u C-n n SPC 5 0 <return> M-> 
Q y n SPC M-> Q y n SPC 5 0 <return> M-> C-u C-p Q 
y s M-v M-v M-v C-u C-u C-p n n n n M-g M-g M-g M-g 
s C-u C-u C-p C-u C-p C-u C-p M-g M-g M-g M-g s C-z 
o <f10> <f10> <f10> <switch-frame> <switch-frame> <f10> 
<switch-frame> n n n C-l n n M-g M-g M-g M-g s n C-l 
M-g M-g M-g p SPC <return> M-> SPC SPC C-z o <f10> 
C-z o SPC SPC <backspace> SPC SPC SPC SPC SPC SPC SPC 
SPC q M-g M-g s C-z o <f10> <f10> C-z o n M-g M-g s 
SPC M-> E q SPC M-> q s <switch-frame> <f10> <f10> 
<f10> I SPC d o n ' t SPC k n o w <return> <f10> C-x 
b i n f r <tab> <return> M-> <f10> n i c e <return> 
<f10> C-x C-v <return> M-> M-v M-v M-v M-v M-v M-v 
M-v M-v M-v M-v M-v M-v M-v M-v M-v M-v M-v M-v M-v 
M-v M-v M-v M-v <f10> <f10> M-v M-v M-v M-v M-v M-v 
M-v M-v M-v M-v C-x b i n f c m d <tab> <return> M-> 
M-v C-x C-f C-g <switch-frame> M-x r e p o r t - e 
m <tab> b <tab> <return>

Recent messages:
Scoring...done
Generating summary...done
Mark set
Expiring articles...done
(No changes need to be saved)
Saving /home/tromey/.newsrc.eld...
Saving file /home/tromey/.newsrc.eld...
Wrote /home/tromey/.newsrc.eld
Saving /home/tromey/.newsrc.eld...done
Mark set [3 times]
Quit
Tom

Message #12 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: bojohan+news <at> dd.chalmers.se (Johan Bockgård)
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#2436: cc mode font-locking -vs- multi-line strings
Date: Fri, 06 Mar 2009 20:31:59 +0100

Tom Tromey <tromey <at> redhat.com> writes:

> Save the attached file as "infcmd.c".  (It comes from GNU gdb.)
> Run emacs -q
> Visit infcmd.c
> Use M-> to go to the end of the buffer.
> Notice that the font-locking is incorrect.
>
> For me, the code at the end of the buffer is fontified as a string,
> whereas it is actually a mix of strings and code.  The badness starts
> at line 2594.

Left Margin Paren strikes again.

Message #15 received at 2436 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: 2436 <at> debbugs.gnu.org
Cc: Tom Tromey <tromey <at> redhat.com>
Subject: Re: bug#2436: cc mode font-locking -vs- multi-line strings
Date: Mon, 03 Oct 2011 15:46:37 -0400

As was pointed out, there is an unescaped left paren in column 0 (at
line 2560). If this is escaped, the problem goes away.

However, there does at least seem to be a documentation bug, because
cc-mode.texi's FAQ says:

    @emph{I have an open paren character at column zero inside a comment or
    multiline string literal, and it causes the fontification and/or
    indentation to go haywire.  What gives?}

    [...]
    This heuristic is built into the core syntax analysis routines in
    (X)Emacs, so it's not really a @ccmode{} issue.  However, in Emacs
    21.1 it became possible to turn it off <at> footnote{Using the variable
    @code{open-paren-in-column-0-is-defun-start}.} and @ccmode{} does so
    there since it's got its own system to keep track of blocks.

However, open-paren-in-column-0-is-defun-start is true in c-mode.
It seems the relevant setting in cc-mode.el was commented out 2006/12/17.

Message #24 received at 2436-done <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: 2436-done <at> debbugs.gnu.org
Subject: Re: bug#2436: cc mode font-locking -vs- multi-line strings
Date: Sun, 19 Jan 2014 22:20:08 -0500

Version: 24.4

Seems fixed by
http://lists.gnu.org/archive/html/emacs-diffs/2014-01/msg00246.html

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