assert.internalTrait

Code example

<?php declare(strict_types = 1);

namespace Vendor {
	/** @internal */
	trait Loggable {
		public function log(string $message): void {}
	}

	class Foo {
		use Loggable;
	}
}

namespace App {
	class Checker {
		/**
		 * @phpstan-assert \Vendor\Loggable $value
		 * @param mixed $value
		 */
		public function assertLoggable($value): void
		{
		}
	}
}

Why is it reported?

A @phpstan-assert PHPDoc tag references a trait 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 types in your assertions creates a fragile dependency on implementation details that can change without notice.

Traits cannot be used as types, so referencing a trait in a @phpstan-assert tag is invalid regardless of the @internal annotation.

How to fix it

Use a public (non-internal) class or interface in the @phpstan-assert tag instead:

 class Checker
 {
 	/**
-	 * @phpstan-assert \Vendor\Loggable $value
+	 * @phpstan-assert \Vendor\PublicInterface $value
 	 * @param mixed $value
 	 */
-	public function assertLoggable($value): void
+	public function assertPublicInterface($value): void
 	{
 	}
 }

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