Re: Building the igc branch on MS-Windows

[Eli Zaretskii <eliz@gnu.org>]

> From: Helmut Eller <eller.helmut@gmail.com>
> Cc: gerd.moellmann@gmail.com,  emacs-devel@gnu.org
> Date: Fri, 26 Apr 2024 10:12:58 +0200
> 
> >     if (FRAME_WINDOW_P (f) && FRAME_OUTPUT_DATA (f))
> >       {
> > 	struct font *font = FRAME_FONT (f);
> > 	if (font)
> > 	  IGC_FIX12_RAW(ss, &font);  <<<<<<<<<<<<<<<<<<<<<
> >       }
> 
> I think this change introduced a bug.  Remember that MPS is moving
> GC. So it sometimes needs to update the pointer in the struct that we
> are scanning.  We have to give it the address of the field, not the
> address of some local variable on the stack. Perhaps clearer is this:
> 
> 	struct font **font = &FRAME_FONT (f);
> 	if (*font)
> 	  IGC_FIX12_RAW(ss, font);

Done.

> > However, the crashes while scrolling through xdisp.c are still there.
> > I just had 2 of them; backtraces below.  It sounds like the first one
> > is due to Lisp strings, but the second one is related to markers.
> >
> >   igc.c:1584: Emacs fatal error: assertion failed: !"other"
> 
> Yes, I see this too.  I will try to write some code to reproduce
> this without needing manual input.

Thanks.