PsySH bootstrap for finding the nearest autoloader. Doesn't pollute the global scope.

bootstrap.php

<?php
call_user_func(function () {
    $autoloader = 'vendor/autoload.php';

    do {
        if (is_readable($autoloader)) {
            require_once $autoloader;
            echo "Autoloader loaded: $autoloader.\n";
            break;
        }

        $autoloader = '../' . $autoloader;
    } while (realpath($autoloader) !== '/');
});