Rule for checking a dynamic call on static methods

Author: lookyman

Diff for: README.md

@@ -10,6 +10,7 @@
 * Functions `in_array` and `array_search` must be called with third parameter `$strict` set to `true` to search values with matching types only.
 * Variables assigned in `while` loop condition and `for` loop initial assignment cannot be used after the loop.
 * Types in `switch` condition and `case` value must match. PHP compares them loosely by default and that can lead to unexpected results.
+* Statically declared methods are called statically.
 
 Additional rules are coming in subsequent releases!
 

Diff for: rules.neon

@@ -32,6 +32,11 @@ services:
 		tags:
 			- phpstan.rules.rule
 
+	-
+		class: PHPStan\Rules\StrictCalls\DynamicCallOnStaticMethodsRule
+		tags:
+			- phpstan.rules.rule
+
 	-
 		class: PHPStan\Rules\StrictCalls\StrictFunctionCallsRule
 		tags:

Diff for: src/Rules/StrictCalls/DynamicCallOnStaticMethodsRule.php

@@ -0,0 +1,63 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\StrictCalls;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\MethodCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\RuleLevelHelper;
+use PHPStan\Type\ErrorType;
+
+class DynamicCallOnStaticMethodsRule implements \PHPStan\Rules\Rule
+{
+
+	/**
+	 * @var \PHPStan\Rules\RuleLevelHelper
+	 */
+	private $ruleLevelHelper;
+
+	public function __construct(RuleLevelHelper $ruleLevelHelper)
+	{
+		$this->ruleLevelHelper = $ruleLevelHelper;
+	}
+
+	public function getNodeType(): string
+	{
+		return MethodCall::class;
+	}
+
+	/**
+	 * @param \PhpParser\Node\Expr\MethodCall $node
+	 * @param \PHPStan\Analyser\Scope $scope
+	 * @return string[]
+	 */
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (!is_string($node->name)) {
+			return [];
+		}
+
+		$name = $node->name;
+		$type = $this->ruleLevelHelper->findTypeToCheck(
+			$scope,
+			$node->var,
+			''
+		)->getType();
+
+		if ($type instanceof ErrorType || !$type->canCallMethods() || !$type->hasMethod($name)) {
+			return [];
+		}
+
+		$methodReflection = $type->getMethod($name, $scope);
+		if ($methodReflection->isStatic()) {
+			return [sprintf(
+				'Dynamic call to static method %s::%s().',
+				$methodReflection->getDeclaringClass()->getDisplayName(),
+				$methodReflection->getName()
+			)];
+		}
+
+		return [];
+	}
+
+}

Diff for: tests/Rules/StrictCalls/DynamicCallOnStaticMethodsRuleTest.php

@@ -0,0 +1,61 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\StrictCalls;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleLevelHelper;
+
+class DynamicCallOnStaticMethodsRuleTest extends \PHPStan\Testing\RuleTestCase
+{
+
+	/**
+	 * @var bool
+	 */
+	private $checkThisOnly;
+
+	protected function getRule(): Rule
+	{
+		$broker = $this->createBroker();
+		$ruleLevelHelper = new RuleLevelHelper($broker, true, $this->checkThisOnly, true);
+		return new DynamicCallOnStaticMethodsRule($ruleLevelHelper);
+	}
+
+	public function testRule(): void
+	{
+		$this->checkThisOnly = false;
+		$this->analyse([__DIR__ . '/data/dynamic-calls-on-static-methods.php'], [
+			[
+				'Dynamic call to static method StrictCalls\ClassWithStaticMethod::foo().',
+				14,
+			],
+			[
+				'Dynamic call to static method StrictCalls\ClassWithStaticMethod::foo().',
+				21,
+			],
+			[
+				'Dynamic call to static method StrictCalls\ClassUsingTrait::foo().',
+				34,
+			],
+			[
+				'Dynamic call to static method StrictCalls\ClassUsingTrait::foo().',
+				46,
+			],
+		]);
+	}
+
+	public function testRuleOnThisOnly(): void
+	{
+		$this->checkThisOnly = true;
+		$this->analyse([__DIR__ . '/data/dynamic-calls-on-static-methods.php'], [
+			[
+				'Dynamic call to static method StrictCalls\ClassWithStaticMethod::foo().',
+				14,
+			],
+			[
+				'Dynamic call to static method StrictCalls\ClassUsingTrait::foo().',
+				34,
+			],
+		]);
+	}
+
+}

Diff for: tests/Rules/StrictCalls/data/dynamic-calls-on-static-methods.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace StrictCalls;
+
+class ClassWithStaticMethod
+{
+	public static function foo()
+	{
+
+	}
+
+	public function bar()
+	{
+		$this->foo();
+		$this->bar();
+	}
+}
+
+function () {
+	$classWithStaticMethod = new ClassWithStaticMethod();
+	$classWithStaticMethod->foo();
+	$classWithStaticMethod->bar();
+};
+
+trait TraitWithStaticMethod
+{
+	public static function foo()
+	{
+
+	}
+
+	public function bar()
+	{
+		$this->foo();
+		$this->bar();
+	}
+}
+
+class ClassUsingTrait
+{
+	use TraitWithStaticMethod;
+}
+
+function () {
+	$classUsingTrait = new ClassUsingTrait();
+	$classUsingTrait->foo();
+	$classUsingTrait->bar();
+};