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

Rector run Failed:

{ "totals": { "changed_files": 0, "errors": 1 }, "errors": [ { "message": "System error: \"Cannot create PHPStan\\Type\\UnionType with: (Doctrine\\Common\\Collections\\ArrayCollection&Doctrine\\Common\\Collections\\Collection)|(Doctrine\\Common\\Collections\\Collection&TReturn), Doctrine\\Common\\Collections\\ArrayCollection\"\nRun Rector with \"--debug\" option and post the report here: https://github.com/rectorphp/rector/issues/new", "file": "/var/www/storage/demo/49jb382ys2fdvip2bmsh/rector_analyzed_file.php", "line": 67 } ] }

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

PHP snippet to change

<?php

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;

$items = ['a', 'b', 'b', 'c'];

$reduces = \array_reduce($items, static function (Collection $carry, string $item) {
    if (!$carry->contains($item)) {
        $carry->add($item);
    }

    return $carry;
}, new ArrayCollection());

Config rector.php

<?php

use Rector\Config\RectorConfig;
use Rector\TypeDeclaration\Rector\FunctionLike\AddClosureParamTypeForArrayReduceRector;

return RectorConfig::configure()
    ->withRules([
        AddClosureParamTypeForArrayReduceRector::class
    ]);

Rector version: b5e58f - released at 2025-09-16 16:38