Casting variable to my class

Hi
I have two class in php file
Below code is my php file
There are no problem in this code
My only problem is PHPStorm cannot show class fields
But when i delcare example $user = new user(); and when i use $user-> , PHPStorm show fields
I need casting variable to user class to show field when i try use this class

PHP Code:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Test extends CI_Controller
{

    function __construct()
    {
        parent::__construct();
    }

    function index() {

        $this->db->select('first_name,last_name');
        $user_c =  $this->db->get('user')->row(0,'user');
        echo $user_c->first_name;

    }

}

class user {
    var $first_name;
    var $last_name;
} 


This picture is when i use class directly
   

And this picture when i use only variable