class.implementsInternalInterface

Code example

<?php declare(strict_types = 1);

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

namespace App {
	class MyClass implements \Vendor\InternalInterface {}
}

Why is it reported?

The interface in the implements clause is marked as @internal by its defining library. Internal symbols are implementation details that can change or be removed without notice in any release. Implementing an internal interface from a third-party package creates a fragile dependency that may break unexpectedly.

How to fix it

Use a public (non-internal) interface provided by the library instead:

-class MyClass implements \Vendor\InternalInterface {}
+class MyClass implements \Vendor\PublicInterface {}

If no public alternative exists, consider whether the library provides a different extension mechanism, such as extending a base class or using composition.