generic with interface typed constrain, can be specialized with class instead

According to feedback on the mail list, the below should not compile (currently it does).

The Param A should be an interface (it may be an interface inheriting from IFoo). But in the example it is a class.

program Project1;
{$Mode objfpc}
{$Interfaces CORBA}
type
  IFoo = interface end;
  TBar = class(TObject, IFoo) end;

  generic MyGen<A: IFoo> = class end;

  TSome = specialize MyGen<TBar>;

begin

end.