parameter.implicitlyNullable

Code example

<?php declare(strict_types = 1);

function doFoo(string $value = null): void
{
}

Why is it reported?

The parameter has a type declaration that does not include null, but its default value is null. This pattern was used in older PHP code to make a parameter implicitly nullable. Starting with PHP 8.4, this implicit nullable pattern is deprecated.

How to fix it

Make the nullable type explicit:

 <?php declare(strict_types = 1);

-function doFoo(string $value = null): void
+function doFoo(?string $value = null): void
 {
 }