invalid.php

<?php

declare(strict_types=1);

class Bar
{
    public function getStuff() : int
    {
        return 1;
    }
}

class BarList
{
    protected $list;

    public function __construct()
    {
        $this->list = [new \Bar()];
    }

    public function getList()
    {
        return $this->list;
    }
}

class Foo
{
    public static function doStuff(BarList $list) : array
    {
        /** @var Bar $bar */
        $bar = $list->getList()[0];
        $bar->invalidMethod();

        $list->getList()[0]->invalidMethod();

        foreach($list->getList() as $fooBar) {
            $fooBar->invalidMethod();
            $fooBar->getStuff();
        }

        return array_values(
            array_map(
                function (Bar $bar) : void {
                    $bar->invalidMethod();
                },
                $list->getList()
            )
        );
    }
}