--TEST--
__clone() can indirectly modify unlocked readonly properties
--FILE--
<?php

class Foo {
    public function __construct(
        public readonly array $bar
    ) {}

    public function __clone()
    {
        $this->bar['bar'] = 'bar';
    }
}

$foo = new Foo([]);
// First call fills the cache slot
var_dump(clone $foo);
var_dump(clone $foo);

?>
--EXPECTF--
object(Foo)#2 (%d) {
  ["bar"]=>
  array(1) {
    ["bar"]=>
    string(3) "bar"
  }
}
object(Foo)#2 (%d) {
  ["bar"]=>
  array(1) {
    ["bar"]=>
    string(3) "bar"
  }
}