[php-src] Issue #15424: Properties (hooks) and inheritance

Issue: https://github.com/php/php-src/issues/15424 Author: SerafimArts ### Description Referenced RFC https://github.com/php/php-src/pull/13455 The following code: ```php <?php interface ExampleInterface {} // parent interface MutableExampleInterface extends ExampleInterface {} // child final class Example implements MutableExampleInterface {} // impl // parent provider interface ExampleProviderInterface { // Any type that implements ExampleInterface can be read public ExampleInterface $property { get; } } // child provider that "overrides" parent definition interface MutableExampleProviderInterface extends ExampleProviderInterface { // Any type that implements (MutableExampleInterface & ExampleInterface) can be read + write // We supplement the object with the installation method public MutableExampleInterface $property { get; set; } } // An implementation that uses implementation final class ExampleProvider implements MutableExampleProviderInterface { public Example $property { // << implementation // We can return the implementation, because it implements (MutableExampleInterface & ExampleInterface) get => $this->property; // Any instance of ExampleInterface is allowed for set, since it satisfies the covariance condition set (ExampleInterface $v) => $this->property = new ExampleImplementation($v); } } ``` Resulted in this output: ``` Fatal error: Type of ExampleProvider::$property must be MutableExampleInterface (as in class MutableExampleProviderInterface) ``` But I expected this output instead: ``` *nothing* ``` Same code (logic) using getters and setters instead of properties: https://onlinephp.io/c/4e180 ```php interface ExampleInterface {} interface MutableExampleInterface extends ExampleInterface {} final class Example implements MutableExampleInterface {} interface ExampleProviderInterface { public function getProperty(): ExampleInterface; } interface MutableExampleProviderInterface extends ExampleProviderInterface { public function getProperty(): MutableExampleInterface; public function setProperty(MutableExampleInterface $value): void; } final class ExampleProvider implements MutableExampleProviderInterface { public function getProperty(): Example {} public function setProperty(ExampleInterface $value): void {} } ``` ### PHP Version PHP 8.4-beta1 ### Operating System _No response_