From: martin rudalics <rudalics@gmx.at>
To: Klaus Zeitler <kzeitler@alcatel-lucent.com>,
635@emacsbugs.donarmstrong.com
Cc: bug-gnu-emacs@gnu.org
Subject: bug#635: Adding font-lock keywords results in no font-lock at all
Date: Tue, 05 Aug 2008 15:12:46 +0200 [thread overview]
Message-ID: <489851CE.1030105@gmx.at> (raw)
In-Reply-To: <200808010621.m716LUC22179@sfsw51.de.lucent.com>
> 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.
The behavior you observe seems due to the change
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.
Get your original behavior back by writing something like
(defun show-tabs () "Show tabs with a slightly changed background"
(unless (or font-lock-keywords font-lock-defaults)
(set (make-local-variable 'font-lock-defaults) '(nil t)))
(font-lock-add-keywords nil '(("\t" (0 'tab-face t))) t))
(add-hook 'font-lock-mode-hook 'show-tabs)
or by removing the offending lines from font-lock.el ;-(
martin
next prev parent reply other threads:[~2008-08-05 13:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
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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