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Error Identifier: mixin.trait

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);

trait MyTrait
{
	public function doFoo(): void
	{
	}
}

/**
 * @mixin MyTrait
 */
class Foo
{
}

Why is it reported? #

A @mixin PHPDoc tag references a trait. Traits cannot be used as types in PHP – they cannot be instantiated or used as a mixin type. The @mixin tag expects a class or object type so that PHPStan knows which methods and properties to forward.

To use a trait’s methods in a class, use the use statement directly in the class body instead of @mixin.

How to fix it #

Use the trait directly with a use statement:

-/**
- * @mixin MyTrait
- */
 class Foo
 {
+	use MyTrait;
 }

Alternatively, replace the trait reference with a class or interface:

-trait MyTrait
+class MyHelper
 {
 	public function doFoo(): void
 	{
 	}
 }

 /**
- * @mixin MyTrait
+ * @mixin MyHelper
  */
 class Foo
 {
 }

How to ignore this error #

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

// @phpstan-ignore mixin.trait
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.trait

Rules that report this error #

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

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