Rule for checking whether a class extends Nette\Object

README.md

@@ -13,6 +13,10 @@ This extension provides following features:
 * Magic [Nette\Object and Nette\SmartObject](https://doc.nette.org/en/2.4/php-language-enhancements) properties
 * Event listeners through the `on*` properties
 
+It also contains this framework-specific rule (can be enabled separately):
+
+* Do not extend Nette\Object, use Nette\SmartObject trait instead
+
 ## Usage
 
 To use this extension, require it in [Composer](https://getcomposer.org/):
@@ -27,3 +31,9 @@ And include extension.neon in your project's PHPStan config:
 includes:
 	- vendor/phpstan/phpstan-nette/extension.neon
 ```
+
+To perform framework-specific checks, include also this file:
+
+```
+	- vendor/phpstan/phpstan-nette/rules.neon
+```

rules.neon

@@ -0,0 +1,5 @@
+services:
+	-
+		class: PHPStan\Rule\Nette\DoNotExtendNetteObjectRule
+		tags:
+			- phpstan.rules.rule

src/Rule/Nette/DoNotExtendNetteObjectRule.php

@@ -0,0 +1,60 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rule\Nette;
+
+use PhpParser\Node;
+use PhpParser\Node\Stmt\Class_;
+use PHPStan\Analyser\Scope;
+use PHPStan\Broker\Broker;
+
+class DoNotExtendNetteObjectRule implements \PHPStan\Rules\Rule
+{
+
+	/** @var \PHPStan\Broker\Broker */
+	private $broker;
+
+	public function __construct(Broker $broker)
+	{
+		$this->broker = $broker;
+	}
+
+	public function getNodeType(): string
+	{
+		return Class_::class;
+	}
+
+	/**
+	 * @param \PhpParser\Node\Stmt\Class_ $node
+	 * @param \PHPStan\Analyser\Scope $scope
+	 * @return string[] errors
+	 */
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (!isset($node->namespacedName)) {
+			// anonymous class - will be possible to inspect
+			// with node visitor and special ClassBody node
+			// because $scope will contain the anonymous class reflection
+			return [];
+		}
+
+		$className = (string) $node->namespacedName;
+		if (!$this->broker->hasClass($className)) {
+			return [];
+		}
+
+		$classReflection = $this->broker->getClass($className);
+		if ($classReflection->isSubclassOf(\Nette\Object::class)) {
+			return [
+				sprintf(
+					"Class %s extends %s - it's better to use %s trait.",
+					$className,
+					\Nette\Object::class,
+					\Nette\SmartObject::class
+				),
+			];
+		}
+
+		return [];
+	}
+
+}