library /*isNonNullableByDefault*/;
import self as self;
import "dart:core" as core;

class D1 extends core::Object {
  synthetic constructor •() → self::D1
    : super core::Object::•()
    ;
}
class D2 extends core::Object {
  synthetic constructor •() → self::D2
    : super core::Object::•()
    ;
}
class D extends core::Object implements self::D1, self::D2 {
  synthetic constructor •() → self::D
    : super core::Object::•()
    ;
}
class A extends core::Object {
  synthetic constructor •() → self::A
    : super core::Object::•()
    ;
  method m(covariant-by-declaration self::D d) → void {}
}
abstract class B1 extends core::Object {
  synthetic constructor •() → self::B1
    : super core::Object::•()
    ;
  abstract method m(self::D1 d1) → void;
}
abstract class B2 extends core::Object {
  synthetic constructor •() → self::B2
    : super core::Object::•()
    ;
  abstract method m(self::D2 d2) → void;
}
static method main() → dynamic {}