Online PHP editor | output for WkL0Y

<?php class T { } class X { public function __construct(T $t) { $this->t = $t; } } class Builder { /** * @var T|null */ public $t; public function createX(): X { $this->validate(); // PHPStan complains that at this line, $this->t could be null, except we've already checked it isn't... // Parameter #1 $t of class X constructor expects T, T|null given. return new X($this->t); } private function validate() { if (is_null($this->t)) { throw new \Exception; } } } $builder = new Builder; $builder->t = new T; $builder->createX();