Description:
------------
I can't implements a Singleton Pattern with inheritance.

Reproduce code:
---------------
abstract class Super {
	public function __construct () {}
}

class Sub extends Super {
	private static $object;
	private function __construct () {}
	
	public static function getInstance() {
		if (!(self::$object instanceof Sub)) {
			self::$object = new Sub();
		}
		return self::$object;
	}
}
$a = Sub::getInstance();


Expected result:
----------------
That worked.


Actual result:
--------------
Fatal error: Access level to Sub::__construct() must be public (as in class Super) in E:\sources\curso\teste\ClasseA.php on line 16