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:

// no change

PHP snippet to change

<?php

abstract class BaseClass
{
}

final class DemoFile extends Base
{
    public function run(bool $param)
    {
        echo "hello, world!";
    }
}

Config rector.php

<?php

declare(strict_types=1);

use Rector\Config\RectorConfig;
use Rector\TypeDeclaration\Rector\ClassMethod\AddReturnTypeDeclarationRector;
use Rector\TypeDeclaration\ValueObject\AddReturnTypeDeclaration;
use PHPStan\Type\VoidType;

return RectorConfig::configure()
    ->withConfiguredRule(AddReturnTypeDeclarationRector::class, [
        new AddReturnTypeDeclaration('BaseClass', 'run', new VoidType()),
    ]);

Rector version: 9a5dde - released at 2026-08-22 13:10