PHP 8.1: Keywords as enum cases

[arokettu]

PHP Fatal error:  Uncaught PhpParser\Error: Syntax error, unexpected T_ARRAY, expecting T_STRING on line 7 in lib/PhpParser/ParserAbstract.php:318

for this code:

<?php

require 'vendor/autoload.php';

enum Types
{
    case Array;
    case Object;
}

$parser = (new \PhpParser\ParserFactory())->create(\PhpParser\ParserFactory::PREFER_PHP7);

$parser->parse(file_get_contents(__FILE__));