[php-src] Issue #9915: Polymorphism not working on abstract method

Issue: https://github.com/php/php-src/issues/9915 Author: roke22 ### Description Hello, This is working fine and is how to use the polymorphism ```php <?php abstract class Class1 { public function __construct(BaseEntity $entity) { echo "Constructor".PHP_EOL; } } class MyClass1 extends Class1 { } class BaseEntity { } class Entity extends BaseEntity { } $class1 = new MyClass1((new Entity)); ``` Resulted in this output: ``` Constructor ``` But when you do the same with an abstract public function like this example: ```php <?php abstract class Class2 { abstract public function test(BaseEntity $entity); } class MyClass2 extends Class2 { public function test(Entity $entity) { echo "Test".PHP_EOL; } } class BaseEntity { } class Entity extends BaseEntity { } $class2 = new MyClass2(); $class2->test((new Entity)); ``` You get the error ``` PHP Fatal error: Declaration of MyClass2::test(Entity $entity) must be compatible with Class2::test(BaseEntity $entity) ``` Whe that should work as expected becuse the $entity parameter is a BaseEntity too. ### PHP Version PHP 7.4.3 (cli) (built: Nov 2 2022 09:53:44) ( NTS ) ### Operating System Ubuntu 20.04