Detect unused variable

Author: ondrejmirtes

conf/bleedingEdge.neon

@@ -28,3 +28,5 @@ parameters:
 		checkImportedClassNameCase: true
 		sortWithoutEffect: true
 		unresolvedTemplateArguments: true
+		unusedVariable: true
+		unusedParameters: true

conf/config.level4.neon

@@ -18,6 +18,12 @@ conditionalTags:
 		phpstan.rules.rule: %featureToggles.finiteTypesInHaystack%
 	PHPStan\Rules\Comparison\SwitchConditionRule:
 		phpstan.rules.rule: %featureToggles.switchConditionAlwaysFalse%
+	PHPStan\Rules\DeadCode\UnusedVariableRule:
+		phpstan.rules.rule: %featureToggles.unusedVariable%
+	PHPStan\Rules\Functions\UnusedFunctionParametersRule:
+		phpstan.rules.rule: %featureToggles.unusedParameters%
+	PHPStan\Rules\Methods\UnusedMethodParametersRule:
+		phpstan.rules.rule: %featureToggles.unusedParameters%
 
 parameters:
 	checkAdvancedIsset: true
@@ -49,3 +55,12 @@ services:
 		class: PHPStan\Rules\Comparison\SwitchConditionRule
 		arguments:
 			treatPhpDocTypesAsCertain: %treatPhpDocTypesAsCertain%
+
+	-
+		class: PHPStan\Rules\DeadCode\UnusedVariableRule
+
+	-
+		class: PHPStan\Rules\Functions\UnusedFunctionParametersRule
+
+	-
+		class: PHPStan\Rules\Methods\UnusedMethodParametersRule

conf/config.neon

@@ -59,6 +59,8 @@ parameters:
 		checkImportedClassNameCase: false
 		sortWithoutEffect: false
 		unresolvedTemplateArguments: false
+		unusedVariable: false
+		unusedParameters: false
 	fileExtensions:
 		- php
 	checkAdvancedIsset: false
@@ -154,6 +156,7 @@ parameters:
 		- ../stubs/ReflectionMethod.stub
 		- ../stubs/ReflectionParameter.stub
 		- ../stubs/ReflectionProperty.stub
+		- ../stubs/ReflectionType.stub
 		- ../stubs/iterable.stub
 		- ../stubs/ArrayObject.stub
 		- ../stubs/WeakReference.stub

conf/parametersSchema.neon

@@ -57,6 +57,8 @@ parametersSchema:
 		checkImportedClassNameCase: bool()
 		sortWithoutEffect: bool()
 		unresolvedTemplateArguments: bool()
+		unusedVariable: bool()
+		unusedParameters: bool()
 	])
 	fileExtensions: listOf(string())
 	checkAdvancedIsset: bool()

e2e/ignore-error-extension/phpstan-baseline.neon

@@ -1,25 +1,25 @@
 parameters:
 	ignoreErrors:
 		-
-			message: '#^This is an error from a rule that uses a collector$#'
+			message: '#^This is an error from a rule that uses a collector\: ClassCollector$#'
 			identifier: class.name
 			count: 1
 			path: src/ClassCollector.php
 
 		-
-			message: '#^This is an error from a rule that uses a collector$#'
+			message: '#^This is an error from a rule that uses a collector\: ClassRule$#'
 			identifier: class.name
 			count: 1
 			path: src/ClassRule.php
 
 		-
-			message: '#^This is an error from a rule that uses a collector$#'
+			message: '#^This is an error from a rule that uses a collector\: ControllerActionReturnTypeIgnoreExtension$#'
 			identifier: class.name
 			count: 1
 			path: src/ControllerActionReturnTypeIgnoreExtension.php
 
 		-
-			message: '#^This is an error from a rule that uses a collector$#'
+			message: '#^This is an error from a rule that uses a collector\: ControllerClassNameIgnoreExtension$#'
 			identifier: class.name
 			count: 1
 			path: src/ControllerClassNameIgnoreExtension.php

e2e/ignore-error-extension/src/ClassRule.php

@@ -29,7 +29,7 @@ public function processNode(Node $node, Scope $scope) : array
 
 		foreach ($node->get(ClassCollector::class) as $file => $data) {
 			foreach ($data as [$className, $line]) {
-				$errors[] = RuleErrorBuilder::message('This is an error from a rule that uses a collector')
+				$errors[] = RuleErrorBuilder::message(sprintf('This is an error from a rule that uses a collector: %s', $className))
 					->file($file)
 					->line($line)
 					->identifier('class.name')

e2e/trait-caching/data/TestClassUsingTrait.php

@@ -15,7 +15,7 @@ public function doBar()
 		return $this->doFoo();
 	}
 
-	public function doBaz(): void
+	public function doBaz(): \stdClass
 	{
 		$class = new class() {
 
@@ -29,6 +29,8 @@ public function doBar()
 				return $this->doFoo();
 			}
 		};
+
+		return $class->doBar();
 	}
 
 }

src/Analyser/ArgsResult.php

@@ -22,11 +22,13 @@ final class ArgsResult
 
 	/**
 	 * @param array<int, ExpressionResult> $argResults keyed by spl_object_id of each argument's value expression
+	 * @param array<int, true> $byRefArguments
 	 */
 	public function __construct(
 		private ExpressionResult $expressionResult,
 		private ?ParametersAcceptor $resolvedParametersAcceptor,
 		private array $argResults,
+		private array $byRefArguments = [],
 	)
 	{
 	}
@@ -72,6 +74,11 @@ public function requireArgResult(Expr $argValue): ExpressionResult
 		return $result;
 	}
 
+	public function isPassedByReference(Expr $arg): bool
+	{
+		return isset($this->byRefArguments[spl_object_id($arg)]);
+	}
+
 	public function getScope(): MutatingScope
 	{
 		return $this->expressionResult->getScope();

src/Analyser/ExprHandler/ArrayDimFetchHandler.php

@@ -23,6 +23,8 @@
 use PHPStan\Analyser\NodeScopeResolver;
 use PHPStan\Analyser\SpecifiedTypes;
 use PHPStan\Analyser\TypeSpecifierContext;
+use PHPStan\Analyser\VariableFlow;
+use PHPStan\Analyser\VariableFlowBuilder;
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Node\Expr\TypeExpr;
 use PHPStan\Reflection\ParametersAcceptorSelector;
@@ -84,6 +86,7 @@ public function composeResult(NodeScopeResolver $nodeScopeResolver, Stmt $stmt,
 				$scope,
 				beforeScope: $beforeScope,
 				expr: $expr,
+				variableFlow: $varResult->getVariableFlow(),
 				hasYield: $varResult->hasYield(),
 				isAlwaysTerminating: $varResult->isAlwaysTerminating(),
 				throwPoints: $varResult->getThrowPoints(),
@@ -118,6 +121,7 @@ public function composeResult(NodeScopeResolver $nodeScopeResolver, Stmt $stmt,
 			$scope,
 			beforeScope: $beforeScope,
 			expr: $expr,
+			variableFlow: VariableFlow::sequence($varResult->getVariableFlow(), $dimResult->getVariableFlow(), VariableFlowBuilder::throws($expr, $throwPoints)),
 			hasYield: $dimResult->hasYield() || $varResult->hasYield(),
 			isAlwaysTerminating: $dimResult->isAlwaysTerminating() || $varResult->isAlwaysTerminating(),
 			throwPoints: $throwPoints,

src/Analyser/ExprHandler/ArrayHandler.php

@@ -16,6 +16,8 @@
 use PHPStan\Analyser\MutatingScope;
 use PHPStan\Analyser\NodeScopeResolver;
 use PHPStan\Analyser\SpecifiedTypes;
+use PHPStan\Analyser\VariableFlow;
+use PHPStan\Analyser\VariableFlowBuilder;
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Node\LiteralArrayItem;
 use PHPStan\Node\LiteralArrayNode;
@@ -53,6 +55,7 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 		$beforeScope = $scope;
 		$itemNodes = [];
 		$itemResults = [];
+		$variableFlows = [];
 		$hasYield = false;
 		$throwPoints = [];
 		$impurePoints = [];
@@ -63,6 +66,7 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 			if ($arrayItem->key !== null) {
 				$keyResult = $nodeScopeResolver->processExprNode($stmt, $arrayItem->key, $scope, $storage, $nodeCallback, $context->enterDeep());
 				$itemResults[spl_object_id($arrayItem->key)] = $keyResult;
+				$variableFlows[] = $keyResult->getVariableFlow();
 				$hasYield = $hasYield || $keyResult->hasYield();
 				$throwPoints = array_merge($throwPoints, $keyResult->getThrowPoints());
 				$impurePoints = array_merge($impurePoints, $keyResult->getImpurePoints());
@@ -72,6 +76,10 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 
 			$valueResult = $nodeScopeResolver->processExprNode($stmt, $arrayItem->value, $scope, $storage, $nodeCallback, $context->enterDeep());
 			$itemResults[spl_object_id($arrayItem->value)] = $valueResult;
+			$variableFlows[] = $valueResult->getVariableFlow();
+			if ($arrayItem->byRef) {
+				$variableFlows[] = VariableFlowBuilder::escapeRoot($arrayItem->value);
+			}
 			$hasYield = $hasYield || $valueResult->hasYield();
 			$throwPoints = array_merge($throwPoints, $valueResult->getThrowPoints());
 			$impurePoints = array_merge($impurePoints, $valueResult->getImpurePoints());
@@ -88,6 +96,7 @@ public function processExpr(NodeScopeResolver $nodeScopeResolver, Stmt $stmt, Ex
 			$scope,
 			beforeScope: $beforeScope,
 			expr: $expr,
+			variableFlow: VariableFlow::sequence(...$variableFlows),
 			hasYield: $hasYield,
 			isAlwaysTerminating: $isAlwaysTerminating,
 			throwPoints: $throwPoints,