library;
import self as self;
import "dart:core" as core;

class _Y<T extends core::Object = dynamic> extends core::Object {
  const constructor •() → self::_Y<self::_Y::T>
    : super core::Object::•()
    ;
}
class A<T extends core::Object = dynamic> extends core::Object {
  generic-covariant-impl field self::_Y<self::A::T> x;
  constructor •(self::_Y<self::A::T> x) → self::A<self::A::T>
    : self::A::x = x, super core::Object::•()
    ;
}
class B<T extends core::Object = dynamic> extends self::A<self::B::T> {
  constructor •() → self::B<self::B::T>
    : super self::A::•(const self::_Y::•<dynamic>())
    ;
}
static method main() → dynamic {
  dynamic x = new self::B::•<dynamic>().x;
  if(!(x is self::_Y<core::Null>)) {
    throw "Unexpected run-time type: `new B().x` is ${x.runtimeType}, but `_Y<Null>` expected";
  }
}