sealed.internalInterface

Code example

<?php declare(strict_types = 1);

namespace Vendor {
	/** @internal */
	interface InternalInterface {}
}

namespace App {
	/** @phpstan-sealed \Vendor\InternalInterface */
	class MyBase {}
}

Why is it reported?

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

How to fix it

Use a public (non-internal) interface in the @phpstan-sealed tag:

-/** @phpstan-sealed \Vendor\InternalInterface */
+/** @phpstan-sealed \Vendor\PublicInterface */
 class MyBase {}

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