Getting the index for an element in mutually referencing containers

[Mart van de Wege <mvdwege@gmail.com>]

I am missing another thing: I managed to boil down the problem to the
PoC code below. I want to have two objects, each with a container as a
record attribute, referring to each other, and then merely get the index
value of one of the two containers. Yet if I do, I get a Storage_Error
exception.

Code:

with Ada.Containers.Indefinite_Vectors;
with Ada.Containers.Indefinite_Doubly_Linked_Lists;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Test_Container is
   type Abstract_Person is abstract tagged null record;
   package Offspring is new Ada.Containers.Indefinite_Vectors
     (Index_Type => Positive,
      Element_Type => Abstract_Person'Class);
   package Group is new Ada.Containers.Indefinite_Doubly_Linked_Lists
     (Element_Type => Abstract_Person'Class);
   type Person is new Abstract_Person with record
      Children : Offspring.Vector := Offspring.To_Vector(4);
      Parents : Group.List;
   end record;
   Father : Person;
   Child : Person;
begin
   Child.Parents.Prepend(Father);
   Father.Children.Append(Child);
   Put(Integer(Father.Children.Find_Index(Child)));
end Test_Container;

This compiles OK, but on runtime throws an exception:

raised STORAGE_ERROR : stack overflow or erroneous memory access

Now, cyclic dependencies are tricky, so I am sure I am doing something
wrong, but I can't for the life of me see what.

Mart

-- 
"We will need a longer wall when the revolution comes."
    --- AJS, quoting an uncertain source.