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:

 
 final class DemoFile
 {
-    public function run(bool $param)
+    public function run(bool $param): int|string
     {
         if ($this->isTrue($param)) {
             return 5;

         return '10';
     }
 
-    private function isTrue($value)
+    private function isTrue(bool $value): bool
     {
         return $value === true;
     }

PHP snippet to change

<?php

final class DemoFile
{
    public function run(bool $param)
    {
        if ($this->isTrue($param)) {
            return 5;
        }

        return '10';
    }

    private function isTrue($value)
    {
        return $value === true;
    }
    
    public function jsonTest()
    {
        $data = [1,2,3,4];
        
        return json_encode($data, JSON_PRETTY_PRINT);
    }
}

Applied Rules:

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Config rector.php

<?php

use Rector\Config\RectorConfig;
use Rector\TypeDeclaration\Rector\Property\TypedPropertyFromAssignsRector;
use Rector\Php73\Rector\FuncCall\JsonThrowOnErrorRector;
use Rector\ValueObject\PhpVersion;

return RectorConfig::configure()
    // A. whole set
    ->withPreparedSets(typeDeclarations: true)
    // B. or few rules
    ->withRules([
        TypedPropertyFromAssignsRector::class,
        JsonThrowOnErrorRector::class
    ])
    // demonstrate specific PHP version
    ->withPhpVersion(PhpVersion::PHP_84);

Rector version: 142f1c - released at 2026-02-06 17:31