parameter.notOptional

Code example

<?php declare(strict_types = 1);

class Foo
{
	public function doFoo(int $i, int $j = 0): void
	{
	}
}

class Bar extends Foo
{
	public function doFoo(int $i, int $j): void
	{
	}
}

Why is it reported?

The overriding method makes a parameter required that is optional in the parent method. In the example above, parameter $j has a default value in Foo::doFoo() (making it optional), but the overriding method Bar::doFoo() declares $j without a default value (making it required).

This violates the Liskov Substitution Principle. Code that calls $foo->doFoo(1) with only one argument would break when $foo is an instance of Bar, because Bar::doFoo() requires two arguments.

How to fix it

Make the parameter optional in the child class to match the parent:

 class Bar extends Foo
 {
-	public function doFoo(int $i, int $j): void
+	public function doFoo(int $i, int $j = 0): void
 	{
 	}
 }