Re: Redisplay crash

[Kenichi Handa <handa@m17n.org>]

In article <87r7uyfoz9.fsf-monnier+emacs@alfajor.local>, Stefan Monnier <monnier@iro.umontreal.ca> writes:
> There was a discussion about it with Gerd which led to

> 2002-08-27  Gerd Moellmann  <gerd.moellmann@t-online.de>

> 	* xdisp.c (redisplay_updating_p): Variable removed.
> 	(inhibit_free_realized_faces, Qinhibit_free_realized_faces):
> 	New variables.
> 	(init_iterator): Don't free realized faces if
> 	inhibit_free_realized_faces is set.
> 	(redisplay_internal): Bind Qinhibit_free_realized_faces to nil.
> 	(syms_of_xdisp): DEFVAR_BOOL inhibit-free-realized-faces,
> 	initialize Qinhibit_free_realized_faces.

> 	* dispextern.h (PRODUCE_GLYPHS): Set inhibit_free_realized_faces
> 	when iterator is adding glyphs to a glyph matrix.

> I can't find trace of this discussion, tho.
> I've always had the impression that the above patch didn't really fix the
> problem, tho it made it less frequent, so maybe it only hid the problem
> more than fix it, I don't know.  In any case I figure maybe you'd like
> to know.

Thank you for the info.  I found at least one way to crash
Emacs constantly.

At first, evaluate this in *scratch* buffer.

(put-text-property 2 3 'display '(when (clear-face-cache t)))

Then, type C-h h C-x C-k (i.e. view HELLO file and kill that
buffer).

Then, Emacs crashes in get_next_display_element at:

      /* Adjust face id for a multibyte character.  There are no
         multibyte character in unibyte text.  */
      if (it->multibyte_p
	  && success_p
	  && FRAME_WINDOW_P (it->f))
	{
	  struct face *face = FACE_FROM_ID (it->f, it->face_id);
here->	  it->face_id = FACE_FOR_CHAR (it->f, face, it->c);
	}

because FACE_FROM_ID returns NULL.

But, it seems that this is a different bug.

---
Ken'ichi HANDA
handa@m17n.org