sharing static property with PHP

<?php

trait t {
    public static $c = 1;
    
    static function foo() {
        echo ++t::$c;
        // This leaves the property in the local structure
        //echo ++self::$c;
    }
}

class x { use t; }
class y { use t; }

echo x::foo();
echo t::foo();
echo y::foo();