Re: hi-lock mode and special buffers

[Chong Yidong <cyd@stupidchicken.com>]

Romain Francoise <romain@orebokech.com> writes:

> This change:
>
> 2005-11-12  Chong Yidong  <cyd@stupidchicken.com>
>
> 	* hi-lock.el (hi-lock-mode): Set the default value of
> 	font-lock-defaults.
>
> breaks fontification in special buffers if hi-lock mode is enabled.
> This affects Gnus and ERC, among others; see Bill's report about Gnus
> (<9993.1131326507@olgas.newt.com>) and the following Debian bug:
>
>     <URL: http://bugs.debian.org/339920>
>
> What was this change supposed to fix?  Is there a better way?

The bug is "No highlight in compilation-minor-mode when hi-lock-mode
is on", at

http://lists.gnu.org/archive/html/emacs-pretest-bug/2005-11/msg00173.html

The old behavior of hi-lock mode is that it sets the
font-lock-defaults to '(nil) when it is turned on.  However,
font-lock-defaults is buffer-local, so the value for other buffers is
unchanged, even though hi-lock-mode applies to them as well.  That was
the source of the incompatibility with compilation-minor-mode.