Syntax error anonymous readonly class #2452

<?php

abstract readonly class Foo {
  public function bar() {
    echo 'bar';
  }
}

$foo = new readonly class extends Foo{};
echo $foo->bar();

Parse Error : syntax error, unexpected 'readonly' (T_READ_ONLY) on line 9

   7 | }
   8 |
>  9 | $foo = new readonly class extends Foo{};
     |           ^
  10 | echo $foo->bar();