Description:
------------
Problem with create of object class then contruct is private. I use singleton pattern and inheritance and I can create object (no error and warning) if i didn't use inheritance was error (this behavior is ok).

Reproduce code:
---------------
<?php
class DB extends mysqli{
    private static $instance;
    
    private function __construct($hostname=DB_HOST, $username=DB_USER, $password=DB_PASSWORD, $database=DB_DATABASE){        
        //parent::__construct($hostname, $username, $password, $database);
    }
    
    public static function getInstance() {
        if (!isset(self::$instance)) {
            self::$instance = new DB();
        } 
        return self::$instance;
    }
}

$DB = new DB();
?>

Expected result:
----------------
Fatal error: Call to private DB::__construct() 

Actual result:
--------------
Everything is ok. No error! No warning!