PHP 8.4 Nullable Types

Now with PHP 8.4 this behaviour is deprecated and should be explicitly marked as nullable.

Example

public static function dialogSettings(LayoutParagraphsLayout $layout = NULL) {
}

Fixing it is extremely easy and backwards compatible at least to 8.0 - in most cases, single character - ? - plus docstring updates. For example:

public static function dialogSettings(?LayoutParagraphsLayout $layout = NULL) {
}

Manual fixes are easy, but automatic fixes (or at least checks) are faster.

You can use PHP CodeSniffer's PHP Code Beautifier and Fixer, specifically using a sniff from slevomat/coding-standard SlevomatCodingStandard.TypeHints.NullableTypeForNullDefaultValue.  If so, run phpcbf [path].

Or, you can use PHP Coding Standards Fixer by Symfony. Note, this example includes files for Drupal support, adjust file types as needed for your use case. Need to create a config file such as this (name/location can be whatever you want):

<?php
$finder = \PhpCsFixer\Finder::create()
    ->in(__DIR__)
    ->name('*.engine')
    ->name('*.module')
    ->name('*.profile')
    ->name('*.theme')
    ->name('*.inc')
    ->name('*.php');

$config = new \PhpCsFixer\Config();
$config->setParallelConfig(PhpCsFixer\Runner\Parallel\ParallelConfigFactory::detect());
return $config->setRules([
        'nullable_type_declaration_for_default_null_value' => true,
    ])
    ->setFinder($finder);

and then run fix (or run check if you want to get a report first).

php-cs-fixer fix --config config-file.php [path]