PHPStan extension to extract property type hint from constructor argument

README.md

PHPStan Extension

Why?

See phpstan/phpstan#1562

Installation

Add the following lines your .phpstan.neon:

For version < 9:

services:
    -
        class: Tests\Phpstan\BrokerFactory
    broker:
        class: PHPStan\Broker\Broker
        factory: @Tests\Phpstan\BrokerFactory::create

else:

services:
    brokerFactory:
        class: Tests\Util\BrokerFactory

BrokerFactory.php

<?php

use PHPStan\Broker\Broker;
use PHPStan\Broker\BrokerFactory as PhpstanBrokerFactory;
use PHPStan\Reflection\ClassReflection;
use PHPStan\Reflection\Php\PhpPropertyReflection;
use PHPStan\Reflection\PropertiesClassReflectionExtension;
use PHPStan\Reflection\PropertyReflection;
use PHPStan\Type\ObjectType;

class BrokerFactory extends PhpstanBrokerFactory
{
    public function create(): Broker
    {
        $broker = parent::create();

        $r = new \ReflectionProperty($broker, 'propertiesClassReflectionExtensions');
        $r->setAccessible(true);

        $propertiesClassReflectionExtensions = $r->getValue($broker);
        array_unshift($propertiesClassReflectionExtensions, new PropertiesClassReflectionBasedOnConstructor());
        $r->setValue($broker, $propertiesClassReflectionExtensions);

        return $broker;
    }
}

class PropertiesClassReflectionBasedOnConstructor implements PropertiesClassReflectionExtension
{
    public function hasProperty(ClassReflection $classReflection, string $propertyName): bool
    {
        return $this->extractFromConstructor($classReflection->getNativeReflection(), $propertyName);
    }

    public function getProperty(ClassReflection $classReflection, string $propertyName): PropertyReflection
    {
        $nativeClassReflection = $classReflection->getNativeReflection();

        foreach ($nativeClassReflection->getConstructor()->getParameters() as $parameter) {
            if ($propertyName !== $parameter->name) {
                continue;
            }

            $type = new ObjectType((string) $parameter->getType());

            return new PhpPropertyReflection($classReflection, $type, $nativeClassReflection->getProperty($propertyName), false, false);
        }
    }

    private function extractFromConstructor(\ReflectionClass $nativeClassReflection, string $propertyName)
    {
        if (!$nativeClassReflection->hasProperty($propertyName)) {
            return false;
        }

        $constructor = $nativeClassReflection->getConstructor();
        if (!$constructor) {
            return false;
        }

        foreach ($constructor->getParameters() as $parameter) {
            if ($propertyName !== $parameter->name) {
                continue;
            }

            if (!$parameter->getType()) {
                return false;
            }

            if ($parameter->isOptional()) {
                return false;
            }

            return class_exists((string) $parameter->getType());
        }

        if ($parentClass = $nativeClassReflection->getParentClass()) {
            try {
                $reflectionClass = new \ReflectionClass($parentClass);
            } catch (\ReflectionException $e) {
                return false;
            }

            return $this->extractFromConstructor($reflectionClass, $propertyName);
        }

        return false;
    }
}