Install via Composer:

composer require --dev nette/phpstan-rules

Requirements: PHP 8.1 or higher and PHPStan 2.1+.

If you use phpstan/extension-installer, the extension is registered automatically. Otherwise add to your phpstan.neon:

includes:
    - vendor/nette/phpstan-rules/extension.neon

Precise return types — narrows return types of Strings::match(), matchAll(), split(), Helpers::falseToNull(), Expect::array(), Arrays::invoke(), and Arrays::invokeMethod() based on the arguments you pass.

Removes |false and |null from PHP functions — many native functions like getcwd, json_encode, preg_split, preg_replace, and many more include false or null in their return type even though these error values are unrealistic on modern systems.

Assert type narrowing — PHPStan understands type guarantees after Tester\Assert calls like notNull(), type(), true(), etc.

False positive suppression — silences known PHPStan false positives in Nette patterns (arrow functions passed as void callbacks, runtime type validation closures).

For Nette package developers: TypeAssert lets you verify type inference in tests using Nette Tester:

use Nette\PHPStan\Tester\TypeAssert;

TypeAssert::assertTypes(__DIR__ . '/data/types.php');
TypeAssert::assertNoErrors(__DIR__ . '/data/clean.php');

The data file uses assertType() from PHPStan:

use function PHPStan\Testing\assertType;

assertType('non-empty-string', getcwd());
assertType('string', Normalizer::normalize('foo'));

Do you like Nette? Are you looking forward to the new features?

Thank you!