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Error Identifier: instanceof.internalInterface

Every error reported by PHPStan has an error identifier. Here’s a list of all error identifiers. In PHPStan Pro you can see the error identifier next to each error and filter errors by their identifiers.

Code example #

<?php declare(strict_types = 1);

namespace App;

use Some\Internal\InternalInterface;

function checkHandler(object $obj): void
{
	if ($obj instanceof InternalInterface) { // ERROR: Instanceof references internal interface InternalInterface.
		// ...
	}
}

Why is it reported? #

The interface used in the instanceof expression has been marked as @internal. Internal interfaces are not part of the public API of the package that defines them. Relying on internal types in instanceof checks creates a dependency on implementation details that may change without notice in future versions of the package.

How to fix it #

Use a public interface or class provided by the package instead:

 <?php declare(strict_types = 1);
 
 namespace App;

-use Some\Internal\InternalInterface;
+use Some\PublicInterface;

 function checkHandler(object $obj): void
 {
-	if ($obj instanceof InternalInterface) {
+	if ($obj instanceof PublicInterface) {
 		// ...
 	}
 }

If no public alternative exists, contact the package maintainer to request a public API.

How to ignore this error #

You can use the identifier instanceof.internalInterface to ignore this error using a comment:

// @phpstan-ignore instanceof.internalInterface
codeThatProducesTheError();

You can also use only the identifier key to ignore all errors of the same type in your configuration file in the ignoreErrors parameter:

parameters:
	ignoreErrors:
		-
			identifier: instanceof.internalInterface

Rules that report this error #

  • PHPStan\Rules\InternalTag\RestrictedInternalClassNameUsageExtension [1]

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