Re: font locking problem

[Alan Mackenzie<none@example.invalid>]

Lowell Kirsh <lkirsh@cs.ubc.ca> wrote on Wed, 05 May 2004 14:12:54 -0700:
> Alan Mackenzie wrote:
>> Would you tell us your Emacs version number (M-x emacs-version) and your
>> CC Mode version number (M-x c-version), please.

> emacs-version: 21.3.1
> c-version: 5.28

OK, thanks!  These two certainly _ought_ to work sensibly together.

>> That's an internal coding error, probably in CC Mode.  Try setting
>> `debug-on-error'  (M-: (setq debug-on-error t)), then visit the file again.
>> That should give a stack dump.

> Here's a stack dump:

> Debugger entered--Lisp error: (wrong-type-argument integer-or-marker-p nil)
>    goto-char(nil)
>    eval((goto-char (match-beginning 4)))         <====================
>    font-lock-fontify-keywords-region(1 1515 t)   <====================
>    font-lock-default-fontify-region(1 1515 t)
>    font-lock-fontify-region(1 1515 t)
>    byte-code("?Ã \x18Ä?Åed	#?Æ ?Ç\x12+Ã?" [save-match-data-internal verbose 
> font-lock-fontified match-data ((set-match-data 
> save-match-data-internal)) font-lock-fontify-region 
> font-lock-after-fontify-buffer t] 4)
>    font-lock-default-fontify-buffer()
>    font-lock-fontify-buffer()
>    font-lock-mode()
>    turn-on-font-lock()
>    turn-on-font-lock-if-enabled()
>    global-font-lock-mode-buffers()
>    run-hooks(find-file-hooks)
>    after-find-file(nil t)
>    find-file-noselect-1(#<buffer FileTokenizer.java> 
> "~/java/FileTokenizer.java" nil nil "~/java/FileTokenizer.java" (3385326 
> 775))
>    find-file-noselect("~/java/FileTokenizer.java" nil nil 1)
>    find-file("~/java/FileTokenizer.java" 1)
>    call-interactively(find-file)

Quick question:  does this problem happen with any file.java, or is it
only FileTokenizer.java which crashes?  If the latter, is there a
(java) syntactic error in this file?  [Just for clarity:  even if there
is such an error, Emacs shouldn't be bailing out on it ;-]

I've had a look at the code in font-lock.el, but can't make much of the
information in the dump.  (In particular, I can't see the connection
between the two lines of the dump I've marked with "<=======", which is
the critical bit.  Stefan, what am I missing?)

The file FileTokenizer.java is only 1515 bytes long, isn't it?  Could you
possibly post it here (or even email it to me on acm@muc.de), so that I
could step through it with a debugger?

> So, what should I do? Work around this error until the next version 
> comes out? I'd rather do that than build from the newest cvs source 
> (laziness).

Yes, I can certainly empathise with you on that one.  ;-)

One thing to do would be to try with `jit-lock-mode' in place of
`lazy-lock-mode'.  jit-lock is based on the same ideas as lazy-lock.  It
was a reimplementation done after it emerged that there were fundamental
problems with lazy-lock.

> Lowell

-- 
Alan Mackenzie (Munich, Germany)
Email: aacm@muuc.dee; to decode, wherever there is a repeated letter
(like "aa"), remove half of them (leaving, say, "a").