Problem with access parameter

[402450@cepsz.unizar.es (Jano)]

Hi,

I'm trying to finalize data inside a protected type, using the
approach pasted at the end. I'm not sure if I get this bizarre error
because of a Gnat 3.15p bug or because what I'm trying is illegal:

agpl-counter-multi.ads:59:04: expected an access type with designated
type "Object" defined at line 59
agpl-counter-multi.ads:59:04: found an access type with designated
type derived from "Object" defined at line 59
agpl-counter-multi.ads:59:04:   ==> in call to "_Init_Proc" at line 73

The package code is: (trimmed)

package Agpl.Counter.Multi is

   type Object;
   type Object_Access is access all Object;

   type Destructor_Type (Parent : access Object) is limited private; 

   ----------------------------------------------------------------
   -- Object                                                     --
   ----------------------------------------------------------------
   protected type Object is
      -- Things
   private
      procedure Destroy;
      Destructor : Destructor_Type (Object'Access);
      Values     : Counter_Map.Container_Type;
   end Object;

private

   type Destructor_Type (Parent : access Object) is new   
   Finalization.Limited_Controlled with null record;

   procedure Finalize (This : in out Destructor_Type);
   -- Here call to This.Parent.Destroy;

end Agpl.Counter.Multi;