bug#19554: 25.0.50; void-function xref-marker-stack-empty-p and subsequent abort

[martin rudalics]

> Calling the Lisp debugger in some sensitive place during creating a
> frame is known to cause this.  If you can track this down and see
> why we increment the reference count of the new frame where we
> shouldn't, or declare the frame "official" too soon, perhaps this can
> be fixed.  But it's a low-priority issue, because this assertion
> disappears in an optimized binary anyway.

I suppose it's the same as bug#10296 then.

> The main problem to tackle
> is why do you get a Lisp error in this scenario -- that's the real
> problem to fix.

Indeed.  Another clue might be that when I try to access the menu bar
with the mouse I get

Debugger entered--Lisp error: (void-function xref-marker-stack-empty-p)
  (xref-marker-stack-empty-p)
  (not (xref-marker-stack-empty-p))

martin