Who is wrong, me or GNAT? :-)

["Mark Lundquist" <no.spam@getalife.com>]

OK, here's the code:

--------------------------------------------
-- foo.adb
--------------------------------------------

 procedure Foo is

  package P is
   type T is abstract tagged null record;
   function Create return T is abstract;
  end P;


  package P1 is
   type T2 is new P.T with private;
  private
   type T1 is new P.T with null record;
   function Create return T1;

   type T2 is new T1 with null record;
   --
   -- Gnat takes error on this ^^^ line.
   --
   -- But T2 should inherit 'Create' from
   -- (concrete) type T1.

  end P1;

  package body P1 is
   function Create return T1 is
   begin
    return (null record);
   end Create;
  end P1;

 begin
  null;
 end Foo;
----------------------------------------

GNAT 3.13(p) says:
foo.adb:16:30: type must be declared abstract or "Create" overridden

Is this a bug in GNAT?  If not, what am I missing?

I was trying to come up with an idiom for inherited constructors for
descendants of an abstract tagged type, and this seemed like it ought to do
the trick (although it suffers from the fact that the intermediate derived
type, e.g. T1 in this case, would have to override all the abstract
primitives).

Any help appreciated...
thx
-- mark