Error Identifier: class.disallowedSubtype

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);

/**
 * @phpstan-sealed(AllowedChild)
 */
abstract class Base
{
}

class AllowedChild extends Base
{
}

class DisallowedChild extends Base
{
}

Why is it reported? #

The parent class or interface restricts which types are allowed to extend or implement it using the @phpstan-sealed PHPDoc tag (or the AllowedSubTypes interface). The class in question is not listed among the allowed subtypes.

In the example above, Base only allows AllowedChild as a subtype. DisallowedChild is not in the allowed list, so it is reported.

This mechanism is useful for simulating sealed classes or closed type hierarchies, ensuring that only a known set of types can extend or implement a given base type.

How to fix it #

Add the class to the list of allowed subtypes in the parent:

 <?php declare(strict_types = 1);
 
 /**
- * @phpstan-sealed(AllowedChild)
+ * @phpstan-sealed(AllowedChild, DisallowedChild)
  */
 abstract class Base
 {
 }

Or extend a different class that allows subtyping:

 <?php declare(strict_types = 1);
 
-class DisallowedChild extends Base
+class DisallowedChild extends AllowedChild
 {
 }

How to ignore this error #

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

// @phpstan-ignore class.disallowedSubtype
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.disallowedSubtype

Rules that report this error #

PHPStan\Rules\Classes\AllowedSubTypesRule [1]

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