Re: Building the igc branch on MS-Windows

[Eli Zaretskii]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: eller.helmut@gmail.com,  emacs-devel@gnu.org
> Date: Sat, 27 Apr 2024 14:09:26 +0200
> 
> Inaccessible memory in my experience so far means that the corresponding
> object has either been moved by MPS, or it has been "freed", by not
> copying it.
> 
> So, as an ansatz, let's assume the font in question has been moved. It
> would follow, I think, that it is not a face->font right? Because
> otherwise the reference to the the font would have been traced. The
> question would be where the reference to the font comes from?

It _is_ face->font.  We get to it like this:

  void
  gui_produce_glyphs (struct it *it)
  {
    int extra_line_spacing = it->extra_line_spacing;

    it->glyph_not_available_p = false;

    if (it->what == IT_CHARACTER)
      {
        unsigned char2b;
        struct face *face = FACE_FROM_ID (it->f, it->face_id);
        struct font *font = face->font; <<<<<<<<<<<<<<<<<<<<<<<<<<<<

IOW, the display iterator references a face by its ID, and we access
that face via the frame's face cache.  As I wrote in a previous
message, all the faces in the cache after index 21 are clobbered,
although the cache's 'used' count is 57, and the index of the
problematic face is 22.