Dynamic return type extension for getComponent

Author: ondrejmirtes

composer.json

@@ -7,6 +7,7 @@
 	"require": {
 		"php": "~7.0",
 		"phpstan/phpstan": "^0.6",
+		"nette/component-model": "^2.3.0",
 		"nette/utils": "^2.3.0"
 	},
 	"require-dev": {

extension.neon

@@ -23,3 +23,8 @@ services:
 		class: PHPStan\Reflection\Nette\SmartObjectPropertiesClassReflectionExtension
 		tags:
 			- phpstan.broker.propertiesClassReflectionExtension
+
+	-
+		class: PHPStan\Type\Nette\ComponentModelDynamicReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicMethodReturnTypeExtension

src/Type/Nette/ComponentModelDynamicReturnTypeExtension.php

@@ -0,0 +1,69 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Nette;
+
+use PhpParser\Node\Expr\MethodCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\BrokerAwareClassReflectionExtension;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\Type\DynamicMethodReturnTypeExtension;
+use PHPStan\Type\MixedType;
+use PHPStan\Type\Type;
+
+class ComponentModelDynamicReturnTypeExtension implements DynamicMethodReturnTypeExtension, BrokerAwareClassReflectionExtension
+{
+
+	/** @var \PHPStan\Broker\Broker */
+	private $broker;
+
+	public function setBroker(\PHPStan\Broker\Broker $broker)
+	{
+		$this->broker = $broker;
+	}
+
+	public static function getClass(): string
+	{
+		return \Nette\ComponentModel\Container::class;
+	}
+
+	public function isMethodSupported(
+		MethodReflection $methodReflection
+	): bool
+	{
+		return $methodReflection->getName() === 'getComponent';
+	}
+
+	public function getTypeFromMethodCall(
+		MethodReflection $methodReflection,
+		MethodCall $methodCall,
+		Scope $scope
+	): Type
+	{
+		$calledOnType = $scope->getType($methodCall->var);
+		$mixedType = new MixedType();
+		if ($calledOnType->getClass() === null || !$this->broker->hasClass($calledOnType->getClass())) {
+			return $mixedType;
+		}
+
+		$args = $methodCall->args;
+		if (count($args) !== 1) {
+			return $mixedType;
+		}
+
+		$arg = $args[0]->value;
+		if (!$arg instanceof \PhpParser\Node\Scalar\String_) {
+			return $mixedType;
+		}
+
+		$componentName = $arg->value;
+
+		$class = $this->broker->getClass($calledOnType->getClass());
+		$methodName = sprintf('createComponent%s', ucfirst($componentName));
+		if (!$class->hasMethod($methodName)) {
+			return $mixedType;
+		}
+
+		return $class->getMethod($methodName)->getReturnType();
+	}
+
+}