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
 
 final class DemoFile

        */
       public function flatten(array $groups): array
       {
-          return array_merge(...array_values($groups));
+          return $groups
+              |> array_values(...)
+              |> array_merge(...);
       }
 }

PHP snippet to change

<?php

final class DemoFile
{
      /**
       * @param  array<int, array<int, string>>  $groups
       * @return array<int, string>
       */
      public function flatten(array $groups): array
      {
          return array_merge(...array_values($groups));
      }
}

Applied Rules:

NestedFuncCallsToPipeOperatorRector

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\Php85\Rector\Expression\NestedFuncCallsToPipeOperatorRector;
use Rector\ValueObject\PhpVersion;

return RectorConfig::configure()
    ->withRules([
        NestedFuncCallsToPipeOperatorRector::class
    ])
    ->withPhpVersion(PhpVersion::PHP_85);

Rector version: 3b8b78 - released at 2026-07-24 13:03