[php-src] Issue #8179: Typed properties: the unset() command mahe property undeclared instead of uninitialized

Issue: https://github.com/php/php-src/issues/8179 Author: jakubboucek ### Description The following code: ```php <?php class Dummy { private string $prop; public function __set($name, $value) { echo "Property '$name' in undeclared!\n"; $this->$name = $value; } } $dummy = new Dummy; // This write to uninitialized property - nothing printed $dummy->prop = 'First attempt'; echo "{$dummy->prop}\n"; unset($dummy->prop); // This write to **undeclared** property - message is printed $dummy->prop = 'Second attempt'; echo "{$dummy->prop}\n"; ``` Resulted in this output: ``` First attempt Property 'prop' in undeclared! Second attempt ``` Live example: https://3v4l.org/ZnWbm But I expected this output instead: ``` First attempt Second attempt ``` The [PHP RFC](https://wiki.php.net/rfc/typed_properties_v2#:~:text=If%20a%20typed%20property%20is%20unset()%2C%20then%20it%20returns%20to%20the%20uninitialized%20state.) is explicitly say: >If a typed property is unset(), then it returns to the >uninitialized state. But it's not true, because the unset() command doesn't returns to the uninitialized state but it's just undeclare them and the uninitialized state is simulated at runtime when somebody is trying to read it. The different is evident when I trying write to property – property in uninitialized state does not call magic __set() method, undeclared property does. ### PHP Version PHP 7.4.0 - 7.4.28, 8.0.1 - 8.0.16, 8.1.0 - 8.1.3 ### Operating System _No response_