return.internalInterface

Code example

<?php declare(strict_types = 1);

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

	class ConcreteClass implements InternalInterface {}
}

namespace App {
	function getHandler(): \Vendor\InternalInterface {
		return new \Vendor\ConcreteClass();
	}
}

Why is it reported?

The return type of a function or method references an interface that is marked as @internal. Internal types are not part of the package's public API and may change or be removed without notice. Exposing an internal interface in a return type creates a dependency on an implementation detail.

How to fix it

Use a public (non-internal) type in the return type instead:

 namespace App {
-	function getHandler(): \Vendor\InternalInterface {
+	function getHandler(): \Vendor\PublicInterface {
 		return new \Vendor\ConcreteClass();
 	}
 }

If no public alternative exists, consider reaching out to the package maintainers to request a public API for your use case.