Online PHP editor | output for B22nE

<?php declare(strict_types=1); class A {} class B extends A {} class C extends B {} class D {} interface InterfaceTest { public function foo(); } abstract class AbstractTest { public abstract function foo(); } class TestAbstractContravariance extends AbstractTest { public function foo(): D {} } class TestAbstractCovariance extends AbstractTest { public function foo(): D {} } class TestInterfaceContravariance implements InterfaceTest { public function foo(): D {} } class TestInterfaceCovariance implements InterfaceTest { public function foo(): D {} }