Error Identifier: selfOut.static

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);

/**
 * @template T
 */
class Collection
{
	/**
	 * @phpstan-self-out self<int>
	 */
	public static function createIntCollection(): void
	{
	}
}

Why is it reported? #

The @phpstan-self-out PHPDoc tag is placed on a static method. This tag is used to narrow the type of $this after a method call, allowing PHPStan to track how the object’s generic type changes through a fluent interface. Since static methods do not operate on an instance ($this is not available), the @phpstan-self-out tag has no meaning on static methods.

How to fix it #

If the method needs to use @phpstan-self-out, make it non-static:

 /**
  * @phpstan-self-out self<int>
  */
-public static function createIntCollection(): void
+public function setIntType(): void
 {
 }

If the method must remain static, remove the @phpstan-self-out tag and use a return type instead:

-/**
- * @phpstan-self-out self<int>
- */
-public static function createIntCollection(): void
+/**
+ * @return self<int>
+ */
+public static function createIntCollection(): self
 {
+	return new self();
 }

How to ignore this error #

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

// @phpstan-ignore selfOut.static
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.static

Rules that report this error #

PHPStan\Rules\PhpDoc\IncompatibleSelfOutTypeRule [1]

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