sealed.internalTrait

Code example

<?php declare(strict_types = 1);

namespace ThirdParty {
	/** @internal */
	trait InternalTrait {}
}

namespace App {
	/**
	 * @phpstan-sealed \ThirdParty\InternalTrait
	 */
	interface HandlerProvider
	{
	}
}

Why is it reported?

The @phpstan-sealed PHPDoc tag references a trait that is marked as @internal in another package. Internal traits are not part of the public API of their package and may change or be removed at any time. Referencing them in a @phpstan-sealed tag creates a dependency on an implementation detail that could break without notice.

How to fix it

Reference only public (non-internal) types in @phpstan-sealed tags:

 <?php declare(strict_types = 1);

 namespace App;

-use ThirdParty\InternalTrait;
+use ThirdParty\PublicClass;

 /**
- * @phpstan-sealed InternalTrait
+ * @phpstan-sealed PublicClass
  */
 interface HandlerProvider
 {
 }

If the trait is internal to the same package, the error will not be reported. The @internal restriction only applies to cross-package usage.