bug#21380: 25.0.50; GTK-induced segfault when scheduling timer from window-configuration-change-hook

[martin rudalics]

> I think the problem is the call to do_pending_window_change in
> xg_frame_resized in gtkutil.c: the commit message (commit 3477e27021db)
> says:
>
> Author:     Martin Rudalics <rudalics@gmx.at>
> AuthorDate: Sun Jul 27 15:21:30 2014 +0200
> Commit:     Martin Rudalics <rudalics@gmx.at>
> CommitDate: Sun Jul 27 15:21:30 2014 +0200
>
>      Complete pixelwise frame/window resizing, add horizontal scrollbar
> support.
>      [...]
>      * gtkutil.c (xg_frame_resized): Don't call
>      do_pending_window_change.
>
> but the diff is:
>
> @@ -883,6 +884,8 @@ xg_frame_resized (struct frame *f, int pixelwidth, int
> pixelheight)
>         change_frame_size (f, width, height, 0, 1, 0, 1);
>         SET_FRAME_GARBAGED (f);
>         cancel_mouse_face (f);
> +
> +      do_pending_window_change (0);
>       }
>   }

Remarkable.  I don't remember why I added them.  And obviously I have no
idea why I wrote the ChangeLog entry in reverse.  Just as if I read diff
output in the wrong direction.

In my understanding the do_pending_window_change call is not needed and
usually should be a noop.  But I have no idea why this particular call
of do_pending_window_change would run ‘window-configuration-change-hook’
and subsequently cause the havoc you describe.  The last
change_frame_size should have just happened three lines before.

> And my current understanding is this bug would not occur if that call were
> removed. The same issue applies to the change to x_set_window_size, but I'm
> not certain about removing either call.

Maybe.  But the cause of the SEGFAULT must be elsewhere.  I have no
idea how

4. make_list interrupted by QUIT

could happen "while the temporary copy is being created" when
timer_check has set Vinhibit_quit to t.

martin