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Error Identifier: class.extendsInternalInterface

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);

// In vendor/some-package/src/InternalInterface.php:
// /** @internal */
// interface InternalInterface {}

// In your code:
class MyClass extends \SomePackage\InternalInterface
{
}

Why is it reported? #

The class extends a type that is marked as @internal and whose type description is an interface. Internal types are not part of the package’s public API and may change or be removed without notice in future versions. Depending on internal types in your code makes it fragile and prone to breaking when the dependency is updated.

Note that in valid PHP, a class cannot extend an interface (it should use implements instead). This error identifies the usage of an internal interface in the extends clause, which is both a misuse of the extends keyword and a violation of the internal API boundary.

How to fix it #

If the type is an interface, use implements instead of extends, and use a non-internal interface:

 <?php declare(strict_types = 1);
 
-class MyClass extends \SomePackage\InternalInterface
+class MyClass implements \SomePackage\PublicInterface
 {
 }

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

How to ignore this error #

You can use the identifier class.extendsInternalInterface to ignore this error using a comment:

// @phpstan-ignore class.extendsInternalInterface
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: class.extendsInternalInterface

Rules that report this error #

• PHPStan\Rules\InternalTag\RestrictedInternalClassNameUsageExtension [1]

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