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* bug#635: Adding font-lock keywords results in no font-lock at all
@ 2008-08-01  6:21 Klaus Zeitler
  2008-08-05 13:12 ` martin rudalics
  2010-10-09  4:11 ` Chong Yidong
  0 siblings, 2 replies; 6+ messages in thread
From: Klaus Zeitler @ 2008-08-01  6:21 UTC (permalink / raw
  To: bug-gnu-emacs


For many years I had the following statement in my .emacs file:

(defun show-tabs () "Show tabs with a slightly changed background"
  (font-lock-add-keywords nil '(("\t"  (0 'tab-face t))) t))
(add-hook 'font-lock-mode-hook 'show-tabs)

This has worked without any problems up to 22.1.
In version 22.2 and 23 I do have problems with syntax highlighting due
to these few lines above in some modes, e.g. when I try M-x list-faces-display
all colors are gone.

To reproduce:

1. start "emacs -Q"
2. in scratch buffer evaluate
(defun show-tabs () "Show tabs with a slightly changed background"
  (font-lock-add-keywords nil '(("\t"  (0 'font-lock-constant-face t))) t))
(add-hook 'font-lock-mode-hook 'show-tabs)
3. M-x list-faces-display
=> everything's displayed in default face



In GNU Emacs 22.2.2 (sparc-sun-solaris2.8, Motif Version 2.1.0)
 of 2008-04-09 on sfsws4
Windowing system distributor `Sun Microsystems, Inc.', version 11.0.6410
configured using `configure  '--with-gcc' '--prefix=/vol/freeware/SunOS-5.8/emacs/22.2' '--sharedstatedir=/vol/freeware/SunOS-5.8/emacs/22.2/share' '--with-x-toolkit=motif' '--x-includes=/usr/openwin/include:/usr/local/gnu/include:/opt/exp/gnu/include:/opt/exp/include:/opt/exp/lib/xpm/include' '--x-libraries=/usr/openwin/lib:/usr/local/gnu/lib:/opt/exp/gnu/lib:/opt/exp/lib:/opt/exp/lib/xpm/lib' '--with-pop' 'CC=gcc' 'XMKMF=/usr/openwin/bin/xmkmf''

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: C
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  tool-bar-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
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  line-number-mode: t

Recent input:
<help-echo> <help-echo> <menu-bar> <help-menu> <se
nd-emacs-bug-report>

Recent messages:
("emacs" "-Q")
For information about GNU Emacs and the GNU system, type C-h C-a.
Loading emacsbug...
Loading regexp-opt...done
Loading emacsbug...done








^ permalink raw reply	[flat|nested] 6+ messages in thread
* bug#635: Adding font-lock keywords results in no font-lock at all
@ 2009-08-13 23:41 Chong Yidong
  2009-08-19  0:14 ` Stefan Monnier
  0 siblings, 1 reply; 6+ messages in thread
From: Chong Yidong @ 2009-08-13 23:41 UTC (permalink / raw
  To: Stefan Monnier; +Cc: 635

> 2007-06-11  Stefan Monnier  <monnier@iro.umontreal.ca>

>     * font-lock.el (font-lock-add-keywords): In case font-lock was only
>       half-activated, forcefully activate it completely.
>
> which added the following lines to `font-lock-add-keywords'

>    (when (and font-lock-mode
>               (not (or font-lock-keywords font-lock-defaults)))
>      ;; The major mode has not set any keywords, so when we enabled
>      ;; font-lock-mode it only enabled the font-core.el part, not the
>      ;; font-lock-mode-internal.  Try again.
>      (font-lock-mode -1)
>      (set (make-local-variable 'font-lock-defaults) '(nil t))
>      (font-lock-mode 1))
>
> What happens appears to be that in any mode that does not specify
> `font-lock-keywords' (like `help-mode' or `view-mode' in your case),
> (font-lock-mode -1) unfontifies the entire buffer thus removing any
> faces assigned earlier by, for example, `list-faces-display'.  Since
> these faces are not reassigned by font-lock you won't get them back
> either :-(
>
> AFAICT, this change also broke `hi-lock-mode' in such buffers.

Maybw we should do away with the optimization where font-lock-mode
avoids calling font-lock-internal when font-lock-defaults is empty.  The
performance benefit is probably negligible.

Stefan, WDYT?





^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-10-09  4:11 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2008-08-01  6:21 bug#635: Adding font-lock keywords results in no font-lock at all Klaus Zeitler
2008-08-05 13:12 ` martin rudalics
2008-08-12  6:43   ` Klaus Zeitler
2010-10-09  4:11 ` Chong Yidong
  -- strict thread matches above, loose matches on Subject: below --
2009-08-13 23:41 Chong Yidong
2009-08-19  0:14 ` Stefan Monnier

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