Try Rector Online | Rector - Automated Way to Instantly Upgrade and Refactor any PHP code

Run Rector on your code to see what it can do for you:

 <?php
 
-new DateTime('now');
+new \DateTimeImmutable('now');

PHP snippet to change

<?php

new DateTime('now');

Applied Rules:

RenameClassRector

Not a change you expect?

Create an issue on GitHub
...or to speed up fix – add a test fixture

Config rector.php

<?php

declare(strict_types=1);

use Rector\Config\RectorConfig;
use Rector\Renaming\Rector\Name\RenameClassRector;

return static function (RectorConfig $rectorConfig): void {
    $rectorConfig->ruleWithConfiguration(RenameClassRector::class, [
        DateTime::class => DateTimeImmutable::class,
    ]);
};

Rector version: 13f7ab - released at 2026-01-07 13:19