Check - disallow variable variables

Author: ondrejmirtes

README.md

@@ -18,6 +18,7 @@
 * 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.
 * Disallow `empty()` - it's a very loose comparison (see [manual](https://php.net/empty)), it's recommended to use more strict one.
+* Disallow variable variables (`$$foo`, `$this->$method()` etc.)
 * Always true `instanceof`, type-checking `is_*` functions and strict comparisons `===`/`!==`. These checks can be turned off by setting `checkAlwaysTrueInstanceof`/`checkAlwaysTrueCheckTypeFunctionCall`/`checkAlwaysTrueStrictComparison` to false.
 * Require parameter and return typehints for functions and methods (either native or phpDocs)
 * Correct case for referenced and called function names.

rules.neon

@@ -36,6 +36,11 @@ rules:
 	- PHPStan\Rules\StrictCalls\DynamicCallOnStaticMethodsRule
 	- PHPStan\Rules\StrictCalls\StrictFunctionCallsRule
 	- PHPStan\Rules\SwitchConditions\MatchingTypeInSwitchCaseConditionRule
+	- PHPStan\Rules\VariableVariables\VariableMethodCallRule
+	- PHPStan\Rules\VariableVariables\VariableStaticMethodCallRule
+	- PHPStan\Rules\VariableVariables\VariableStaticPropertyFetchRule
+	- PHPStan\Rules\VariableVariables\VariablePropertyFetchRule
+	- PHPStan\Rules\VariableVariables\VariableVariablesRule
 
 services:
 	-

src/Rules/VariableVariables/VariableMethodCallRule.php

@@ -0,0 +1,33 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\VariableVariables;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+
+class VariableMethodCallRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return Node\Expr\MethodCall::class;
+	}
+
+	/**
+	 * @param \PhpParser\Node\Expr\MethodCall $node
+	 * @param \PHPStan\Analyser\Scope $scope
+	 * @return string[]
+	 */
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if ($node->name instanceof Node\Identifier) {
+			return [];
+		}
+
+		return [
+			'Variable method calls are not allowed.',
+		];
+	}
+
+}

src/Rules/VariableVariables/VariablePropertyFetchRule.php

@@ -0,0 +1,33 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\VariableVariables;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+
+class VariablePropertyFetchRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return Node\Expr\PropertyFetch::class;
+	}
+
+	/**
+	 * @param \PhpParser\Node\Expr\PropertyFetch $node
+	 * @param \PHPStan\Analyser\Scope $scope
+	 * @return string[]
+	 */
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if ($node->name instanceof Node\Identifier) {
+			return [];
+		}
+
+		return [
+			'Variable properties are not allowed.',
+		];
+	}
+
+}

src/Rules/VariableVariables/VariableStaticMethodCallRule.php

@@ -0,0 +1,33 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\VariableVariables;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+
+class VariableStaticMethodCallRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return Node\Expr\StaticCall::class;
+	}
+
+	/**
+	 * @param \PhpParser\Node\Expr\StaticCall $node
+	 * @param \PHPStan\Analyser\Scope $scope
+	 * @return string[]
+	 */
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if ($node->name instanceof Node\Identifier) {
+			return [];
+		}
+
+		return [
+			'Variable static method calls are not allowed.',
+		];
+	}
+
+}

src/Rules/VariableVariables/VariableStaticPropertyFetchRule.php

@@ -0,0 +1,33 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\VariableVariables;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+
+class VariableStaticPropertyFetchRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return Node\Expr\StaticPropertyFetch::class;
+	}
+
+	/**
+	 * @param \PhpParser\Node\Expr\StaticPropertyFetch $node
+	 * @param \PHPStan\Analyser\Scope $scope
+	 * @return string[]
+	 */
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if ($node->name instanceof Node\VarLikeIdentifier) {
+			return [];
+		}
+
+		return [
+			'Variable static properties are not allowed.',
+		];
+	}
+
+}

src/Rules/VariableVariables/VariableVariablesRule.php

@@ -0,0 +1,33 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\VariableVariables;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+
+class VariableVariablesRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return Node\Expr\Variable::class;
+	}
+
+	/**
+	 * @param \PhpParser\Node\Expr\Variable $node
+	 * @param \PHPStan\Analyser\Scope $scope
+	 * @return string[]
+	 */
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (is_string($node->name)) {
+			return [];
+		}
+
+		return [
+			'Variable variables are not allowed.',
+		];
+	}
+
+}

tests/Rules/VariableVariables/VariableMethodCallRuleTest.php

@@ -0,0 +1,26 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\VariableVariables;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+class VariableMethodCallRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new VariableMethodCallRule();
+	}
+
+	public function testRule(): void
+	{
+		$this->analyse([__DIR__ . '/data/methods.php'], [
+			[
+				'Variable method calls are not allowed.',
+				7,
+			],
+		]);
+	}
+
+}

tests/Rules/VariableVariables/VariablePropertyFetchRuleTest.php

@@ -0,0 +1,30 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\VariableVariables;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+class VariablePropertyFetchRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new VariablePropertyFetchRule();
+	}
+
+	public function testRule(): void
+	{
+		$this->analyse([__DIR__ . '/data/properties.php'], [
+			[
+				'Variable properties are not allowed.',
+				6,
+			],
+			[
+				'Variable properties are not allowed.',
+				9,
+			],
+		]);
+	}
+
+}

tests/Rules/VariableVariables/VariableStaticMethodCallRuleTest.php

@@ -0,0 +1,26 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\VariableVariables;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+class VariableStaticMethodCallRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new VariableStaticMethodCallRule();
+	}
+
+	public function testRule(): void
+	{
+		$this->analyse([__DIR__ . '/data/staticMethods.php'], [
+			[
+				'Variable static method calls are not allowed.',
+				7,
+			],
+		]);
+	}
+
+}