issue with anonymous classes

[EdvinasPocius]

can't use anonymous classes:

<?php

declare(strict_types=1);

namespace Acme;

use stdClass;

class Example
{
    public function magicMethod(): void
    {
        $class = new class() extends stdClass {
        };

        $class->something = 0;
    }
}

gets an error: "PhpBasic convention 1.3: Only one class/interface can be declared per file"
It's mostly used in tests