Error Identifier: selfOut.type

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);

class Collection
{
    /**
     * @phpstan-self-out int
     */
    public function reset(): void
    {
    }
}

Why is it reported? #

The type specified in the @phpstan-self-out PHPDoc tag is not a subtype of the class that declares the method. The @phpstan-self-out tag narrows the type of $this after a method call, so the declared type must be compatible with (a subtype of) the declaring class.

In the example above, int is not a subtype of Collection.

How to fix it #

Change the @phpstan-self-out type to a valid subtype of the declaring class:

 <?php declare(strict_types = 1);
 
+/**
+ * @template T
+ */
 class Collection
 {
     /**
-     * @phpstan-self-out int
+     * @phpstan-self-out self<int>
      */
     public function reset(): void
     {
     }
 }

How to ignore this error #

You can use the identifier selfOut.type to ignore this error using a comment:

// @phpstan-ignore selfOut.type
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: selfOut.type

Rules that report this error #

PHPStan\Rules\PhpDoc\IncompatibleSelfOutTypeRule [1]

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