Error Identifier: enum.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(AllowedEnum)
 */
interface Permission
{
}

enum AllowedEnum: string implements Permission
{
	case Read = 'read';
}

enum DisallowedEnum: string implements Permission
{
	case Write = 'write';
}

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 enum in question is not listed among the allowed subtypes.

In the example above, Permission only allows AllowedEnum as a subtype. DisallowedEnum implements Permission but is not in the allowed list, so it is reported.

This mechanism enforces closed type hierarchies, ensuring that only a known set of types can implement a given interface.

How to fix it #

Add the enum to the list of allowed subtypes:

 <?php declare(strict_types = 1);
 
 /**
- * @phpstan-sealed(AllowedEnum)
+ * @phpstan-sealed(AllowedEnum, DisallowedEnum)
  */
 interface Permission
 {
 }

Or remove the interface implementation if the enum should not be part of this type hierarchy:

 <?php declare(strict_types = 1);
 
-enum DisallowedEnum: string implements Permission
+enum DisallowedEnum: string
 {
 	case Write = 'write';
 }

How to ignore this error #

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

// @phpstan-ignore enum.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: enum.disallowedSubtype

Rules that report this error #

PHPStan\Rules\Classes\AllowedSubTypesRule [1]

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