Re: font-lock is broken

[Stefan Monnier]

> Make a buffer with this content:

> In-reply-to: "foo bar" of Fri, 15 Jul 2005 20:31:33 EDT
> --------

> (2 lines only)
> Then
> M-x mh-letter-mode
> M-x font-lock-fontify-buffer

> You get:
> font-lock-default-fontify-region: Wrong type argument: number-or-marker-p, nil

This is introduced by my recent change to font-lock.el which checks that we
do not get stuck in an empty match.  Problem is that it bumps into a minor
bug in mh-font-lock-field-data:

   (defun mh-font-lock-field-data (limit)
     ...
         (if (and field (mh-letter-skipped-header-field-p field))
             (set-match-data nil)
           (set-match-data (list data-begin data-end data-begin data-end)))
         (goto-char (if (equal point data-end) (1+ data-end) data-end))
         t)))

As you can see, this function sometimes returns non-nil (i.e. it says it's
found a match) but with no begin/end of match 0.

I'm tempted to just revert my patch, since it causes constant run-time
checks and trips up some pre-existing code, only in the hope of occasionally
working around some bugs that would need to be fixed anyway.


        Stefan