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
 
-function foo(int $bar = null){}
+function foo(?int $bar = null){}

PHP snippet to change

<?php

function foo(int $bar = null){}

Applied Rules:

ExplicitNullableParamTypeRector

Not a change you expect?

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

Config rector.php

<?php

use Rector\Config\RectorConfig;
use Rector\Php84\Rector\Param\ExplicitNullableParamTypeRector;
use Rector\ValueObject\PhpVersion;

return RectorConfig::configure()
    ->withRules([
        ExplicitNullableParamTypeRector::class,
    ])
    ->withPhpVersion(PhpVersion::PHP_84);

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