mixin.internalClass

Code example

<?php declare(strict_types = 1);

namespace Vendor {
	/** @internal */
	class InternalMixin {
		public function doFoo(): void {}
	}
}

namespace App {
	/** @mixin \Vendor\InternalMixin */
	class MyClass {}
}

Why is it reported?

The @mixin PHPDoc tag references a class that is marked as @internal. Internal types are not meant to be used outside of the package or namespace where they are defined. Depending on internal classes in @mixin declarations creates a fragile dependency on implementation details that can change without notice.

How to fix it

Use a public (non-internal) class in the @mixin tag instead:

 namespace App {
-	/** @mixin \Vendor\InternalMixin */
+	/** @mixin \Vendor\PublicMixin */
 	class MyClass {}
 }

If you need the functionality provided by the internal class, check whether the library provides a public API, or implement the methods directly in your class.