ConstructorReadonlyAssignToDefaultRector

Move a constant constructor assignment of a readonly property to a property default value

 final class SomeClass
 {
-    public readonly int $number;
+    public readonly int $number = 100;

     public function __construct()
     {
-        $this->number = 100;
     }
 }

Configure your rector.php:

<?php

use Rector\Config\RectorConfig;
use Rector\Php86\Rector\Class_\ConstructorReadonlyAssignToDefaultRector;

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

Other rules in the PHP 8.6 set