Error Identifier: trait.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 AllowedUser
 */
interface UserProvider
{
}

trait UserTrait
{
}

class AllowedUser implements UserProvider
{
	use UserTrait;
}

class DisallowedUser implements UserProvider
{
	use UserTrait;
}

Why is it reported? #

A trait is used in a class that is not allowed to be a subtype of a sealed parent. The parent class or interface restricts which types can extend or implement it using the @phpstan-sealed PHPDoc tag. The class using this trait is not listed among the allowed subtypes.

Note: the trait. prefix in the identifier indicates that the disallowed subtype is a trait definition. This follows the same logic as class.disallowedSubtype but applies when a trait body is checked.

How to fix it #

Add the class to the list of allowed subtypes:

 /**
- * @phpstan-sealed AllowedUser
+ * @phpstan-sealed AllowedUser|DisallowedUser
  */
 interface UserProvider
 {
 }

Or remove the sealed parent from the class declaration:

-class DisallowedUser implements UserProvider
+class DisallowedUser
 {
 	use UserTrait;
 }

How to ignore this error #

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

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

Rules that report this error #

PHPStan\Rules\Classes\AllowedSubTypesRule [1]

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