return.internalTrait

Code example

<?php declare(strict_types = 1);

namespace Vendor {
	/** @internal */
	trait InternalTrait {
		public function doSomething(): void {}
	}

	class Foo {
		use InternalTrait;
	}
}

namespace App {
	/** @return \Vendor\InternalTrait */
	function createObject() {
		return new \stdClass();
	}
}

Why is it reported?

The return type of the function or method references a trait that is marked as @internal. Internal symbols are not meant to be used outside the package or namespace that defines them. Referencing an internal trait in a return type exposes an internal implementation detail in a public API, creating a dependency on something that may change without notice.

Traits should generally not be used as return types, since PHP does not support using traits as type hints.

How to fix it

Replace the internal trait with a public interface or class in the return type:

 namespace App {
-	/** @return \Vendor\InternalTrait */
+	/** @return \Vendor\PublicInterface */
 	function createObject() {
 		return new \stdClass();
 	}
 }

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