← Back to throws.*

Error Identifier: throws.notCovariant

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 Foo
{
	/**
	 * @throws \LogicException
	 */
	public function doSomething(): void
	{
	}
}

class Bar extends Foo
{
	/**
	 * @throws \RuntimeException
	 */
	public function doSomething(): void
	{
	}
}

Why is it reported? #

The @throws type declared on an overriding method is not covariant with the @throws type of the parent method. Covariance means the child’s throw type must be the same as or a subtype of the parent’s throw type.

In the example above, the parent declares @throws \LogicException, but the child declares @throws \RuntimeException. Since RuntimeException does not extend LogicException, this violates the covariance principle. Callers that catch LogicException based on the parent’s contract would not catch RuntimeException.

This rule is controlled by the exceptions.check.throwTypeCovariance configuration option.

How to fix it #

Change the child’s @throws tag to a subtype of the parent’s throw type:

 class Bar extends Foo
 {
 	/**
-	 * @throws \RuntimeException
+	 * @throws \BadFunctionCallException
 	 */
 	public function doSomething(): void
 	{
 	}
 }

BadFunctionCallException is a subtype of LogicException, so it satisfies the covariance requirement.

Alternatively, if the method truly does not throw, use @throws void:

 class Bar extends Foo
 {
 	/**
-	 * @throws \RuntimeException
+	 * @throws void
 	 */
 	public function doSomething(): void
 	{
 	}
 }

How to ignore this error #

You can use the identifier throws.notCovariant to ignore this error using a comment:

// @phpstan-ignore throws.notCovariant
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: throws.notCovariant

Rules that report this error #

• PHPStan\Rules\Exceptions\MethodThrowTypeCovarianceRule [1]

Edit this page on GitHub