Error Identifier: mixin.unresolvableType

← Back to mixin.*

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);

/**
 * @mixin int&string
 */
class QueryBuilder
{
}

Why is it reported? #

The @mixin PHPDoc tag contains a type that PHPStan cannot resolve. This typically happens when the type expression evaluates to an impossible type, uses invalid type syntax, or references types in a way that produces an error during type resolution.

In the example above, int&string is an impossible intersection type – no value can be both int and string at the same time – so PHPStan cannot resolve it to a meaningful type.

How to fix it #

Reference a concrete class directly:

 /**
- * @mixin int&string
+ * @mixin Connection
  */
 class QueryBuilder
 {
 }

If the intent is to use a generic type, declare it with @template first:

+/**
+ * @template T of object
+ * @mixin T
+ */
-/**
- * @mixin int&string
- */
 class QueryBuilder
 {
 }

How to ignore this error #

You can use the identifier mixin.unresolvableType to ignore this error using a comment:

// @phpstan-ignore mixin.unresolvableType
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: mixin.unresolvableType

Rules that report this error #

• PHPStan\Rules\Classes\MixinRule [1]
• PHPStan\Rules\Classes\MixinTraitRule [1]
• PHPStan\Rules\Classes\MixinTraitUseRule [1]