diff --git a/src/Symfony/Component/DependencyInjection/Compiler/AbstractRecursivePass.php b/src/Symfony/Component/DependencyInjection/Compiler/AbstractRecursivePass.php
index 89857f78a8..b1c3546ac3 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/AbstractRecursivePass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/AbstractRecursivePass.php
@@ -68,11 +68,10 @@ abstract class AbstractRecursivePass implements CompilerPassInterface
      * Processes a value found in a definition tree.
      *
      * @param mixed $value
-     * @param bool  $isRoot
      *
      * @return mixed The processed value
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (\is_array($value)) {
             foreach ($value as $k => $v) {
@@ -105,14 +104,11 @@ abstract class AbstractRecursivePass implements CompilerPassInterface
     }
 
     /**
-     * @param Definition $definition
-     * @param bool       $required
-     *
      * @return \ReflectionFunctionAbstract|null
      *
      * @throws RuntimeException
      */
-    protected function getConstructor(Definition $definition, $required)
+    protected function getConstructor(Definition $definition, bool $required)
     {
         if (\is_string($factory = $definition->getFactory())) {
             if (!\function_exists($factory)) {
@@ -161,14 +157,11 @@ abstract class AbstractRecursivePass implements CompilerPassInterface
     }
 
     /**
-     * @param Definition $definition
-     * @param string     $method
-     *
      * @throws RuntimeException
      *
      * @return \ReflectionFunctionAbstract
      */
-    protected function getReflectionMethod(Definition $definition, $method)
+    protected function getReflectionMethod(Definition $definition, string $method)
     {
         if ('__construct' === $method) {
             return $this->getConstructor($definition, true);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/AnalyzeServiceReferencesPass.php b/src/Symfony/Component/DependencyInjection/Compiler/AnalyzeServiceReferencesPass.php
index d71b0138e4..83f568b706 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/AnalyzeServiceReferencesPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/AnalyzeServiceReferencesPass.php
@@ -74,7 +74,7 @@ class AnalyzeServiceReferencesPass extends AbstractRecursivePass
         }
     }
 
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         $lazy = $this->lazy;
         $inExpression = $this->inExpression();
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php b/src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php
index 3ae264f5c8..6af322fbc3 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php
@@ -65,7 +65,7 @@ class AutowirePass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         try {
             return $this->doProcessValue($value, $isRoot);
@@ -80,7 +80,7 @@ class AutowirePass extends AbstractRecursivePass
         }
     }
 
-    private function doProcessValue($value, $isRoot = false)
+    private function doProcessValue($value, bool $isRoot = false)
     {
         if ($value instanceof TypedReference) {
             if ($ref = $this->getAutowiredReference($value)) {
@@ -373,7 +373,7 @@ class AutowirePass extends AbstractRecursivePass
         $this->ambiguousServiceTypes[$type][] = $id;
     }
 
-    private function createTypeNotFoundMessageCallback(TypedReference $reference, $label)
+    private function createTypeNotFoundMessageCallback(TypedReference $reference, string $label)
     {
         $container = new ContainerBuilder($this->container->getParameterBag());
         $container->setAliases($this->container->getAliases());
@@ -386,7 +386,7 @@ class AutowirePass extends AbstractRecursivePass
         };
     }
 
-    private function createTypeNotFoundMessage(ContainerBuilder $container, TypedReference $reference, $label, string $currentId)
+    private function createTypeNotFoundMessage(ContainerBuilder $container, TypedReference $reference, string $label, string $currentId)
     {
         if (!$r = $container->getReflectionClass($type = $reference->getType(), false)) {
             // either $type does not exist or a parent class does not exist
@@ -444,7 +444,7 @@ class AutowirePass extends AbstractRecursivePass
         return sprintf(' You should maybe alias this %s to %s.', class_exists($type, false) ? 'class' : 'interface', $message);
     }
 
-    private function getAliasesSuggestionForType(ContainerBuilder $container, $type, $extraContext = null)
+    private function getAliasesSuggestionForType(ContainerBuilder $container, string $type, $extraContext = null)
     {
         $aliases = [];
         foreach (class_parents($type) + class_implements($type) as $parent) {
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/AutowireRequiredMethodsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/AutowireRequiredMethodsPass.php
index 20d31135a7..c46d71f206 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/AutowireRequiredMethodsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/AutowireRequiredMethodsPass.php
@@ -23,7 +23,7 @@ class AutowireRequiredMethodsPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         $value = parent::processValue($value, $isRoot);
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/CheckArgumentsValidityPass.php b/src/Symfony/Component/DependencyInjection/Compiler/CheckArgumentsValidityPass.php
index e76e94005f..f016a507a1 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/CheckArgumentsValidityPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/CheckArgumentsValidityPass.php
@@ -32,7 +32,7 @@ class CheckArgumentsValidityPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof Definition) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/CheckExceptionOnInvalidReferenceBehaviorPass.php b/src/Symfony/Component/DependencyInjection/Compiler/CheckExceptionOnInvalidReferenceBehaviorPass.php
index eef71587cd..4ffe3540ce 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/CheckExceptionOnInvalidReferenceBehaviorPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/CheckExceptionOnInvalidReferenceBehaviorPass.php
@@ -43,7 +43,7 @@ class CheckExceptionOnInvalidReferenceBehaviorPass extends AbstractRecursivePass
         }
     }
 
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof Reference) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/CheckReferenceValidityPass.php b/src/Symfony/Component/DependencyInjection/Compiler/CheckReferenceValidityPass.php
index 8f2a3bdf70..0349ef7616 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/CheckReferenceValidityPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/CheckReferenceValidityPass.php
@@ -25,7 +25,7 @@ use Symfony\Component\DependencyInjection\Reference;
  */
 class CheckReferenceValidityPass extends AbstractRecursivePass
 {
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if ($isRoot && $value instanceof Definition && ($value->isSynthetic() || $value->isAbstract())) {
             return $value;
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/Compiler.php b/src/Symfony/Component/DependencyInjection/Compiler/Compiler.php
index 58c6e81a04..04ae8d51cb 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/Compiler.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/Compiler.php
@@ -53,12 +53,8 @@ class Compiler
 
     /**
      * Adds a pass to the PassConfig.
-     *
-     * @param CompilerPassInterface $pass     A compiler pass
-     * @param string                $type     The type of the pass
-     * @param int                   $priority Used to sort the passes
      */
-    public function addPass(CompilerPassInterface $pass, $type = PassConfig::TYPE_BEFORE_OPTIMIZATION, int $priority = 0)
+    public function addPass(CompilerPassInterface $pass, string $type = PassConfig::TYPE_BEFORE_OPTIMIZATION, int $priority = 0)
     {
         $this->passConfig->addPass($pass, $type, $priority);
     }
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/DefinitionErrorExceptionPass.php b/src/Symfony/Component/DependencyInjection/Compiler/DefinitionErrorExceptionPass.php
index 5ee0ff1f49..5e7ba3173e 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/DefinitionErrorExceptionPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/DefinitionErrorExceptionPass.php
@@ -26,7 +26,7 @@ class DefinitionErrorExceptionPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof Definition || !$value->hasErrors()) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/InlineServiceDefinitionsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/InlineServiceDefinitionsPass.php
index 9a80286f4e..cb97ed1fb5 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/InlineServiceDefinitionsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/InlineServiceDefinitionsPass.php
@@ -101,7 +101,7 @@ class InlineServiceDefinitionsPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if ($value instanceof ArgumentInterface) {
             // Reference found in ArgumentInterface::getValues() are not inlineable
@@ -155,7 +155,7 @@ class InlineServiceDefinitionsPass extends AbstractRecursivePass
      *
      * @return bool If the definition is inlineable
      */
-    private function isInlineableDefinition($id, Definition $definition)
+    private function isInlineableDefinition(string $id, Definition $definition)
     {
         if ($definition->hasErrors() || $definition->isDeprecated() || $definition->isLazy() || $definition->isSynthetic()) {
             return false;
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php b/src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php
index e39cd4981a..fa6175d0a5 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php
@@ -110,13 +110,9 @@ class PassConfig
     /**
      * Adds a pass.
      *
-     * @param CompilerPassInterface $pass     A Compiler pass
-     * @param string                $type     The pass type
-     * @param int                   $priority Used to sort the passes
-     *
      * @throws InvalidArgumentException when a pass type doesn't exist
      */
-    public function addPass(CompilerPassInterface $pass, $type = self::TYPE_BEFORE_OPTIMIZATION, int $priority = 0)
+    public function addPass(CompilerPassInterface $pass, string $type = self::TYPE_BEFORE_OPTIMIZATION, int $priority = 0)
     {
         $property = $type.'Passes';
         if (!isset($this->$property)) {
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/RegisterEnvVarProcessorsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/RegisterEnvVarProcessorsPass.php
index 852e7ca44a..d3a049399b 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/RegisterEnvVarProcessorsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/RegisterEnvVarProcessorsPass.php
@@ -60,7 +60,7 @@ class RegisterEnvVarProcessorsPass implements CompilerPassInterface
         }
     }
 
-    private static function validateProvidedTypes($types, $class)
+    private static function validateProvidedTypes(string $types, string $class)
     {
         $types = explode('|', $types);
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php b/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
index aeb9641811..ca49092d84 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
@@ -25,7 +25,7 @@ use Symfony\Contracts\Service\ServiceSubscriberInterface;
  */
 class RegisterServiceSubscribersPass extends AbstractRecursivePass
 {
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof Definition || $value->isAbstract() || $value->isSynthetic() || !$value->hasTag('container.service_subscriber')) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/RemoveUnusedDefinitionsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/RemoveUnusedDefinitionsPass.php
index d87ac4fea3..cf1a3ddc7a 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/RemoveUnusedDefinitionsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/RemoveUnusedDefinitionsPass.php
@@ -75,7 +75,7 @@ class RemoveUnusedDefinitionsPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof Reference) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ReplaceAliasByActualDefinitionPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ReplaceAliasByActualDefinitionPass.php
index 9981096361..ca781f2801 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ReplaceAliasByActualDefinitionPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ReplaceAliasByActualDefinitionPass.php
@@ -80,7 +80,7 @@ class ReplaceAliasByActualDefinitionPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if ($value instanceof Reference && isset($this->replacements[$referenceId = (string) $value])) {
             // Perform the replacement
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveBindingsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveBindingsPass.php
index 23fe4cabab..510910fe73 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveBindingsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveBindingsPass.php
@@ -90,7 +90,7 @@ class ResolveBindingsPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if ($value instanceof TypedReference && $value->getType() === (string) $value) {
             // Already checked
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveChildDefinitionsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveChildDefinitionsPass.php
index b641b357d5..941070e7f5 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveChildDefinitionsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveChildDefinitionsPass.php
@@ -28,7 +28,7 @@ class ResolveChildDefinitionsPass extends AbstractRecursivePass
 {
     private $currentPath;
 
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof Definition) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveEnvPlaceholdersPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveEnvPlaceholdersPass.php
index 9e1edd4d31..ea52b14592 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveEnvPlaceholdersPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveEnvPlaceholdersPass.php
@@ -18,7 +18,7 @@ use Symfony\Component\DependencyInjection\Definition;
  */
 class ResolveEnvPlaceholdersPass extends AbstractRecursivePass
 {
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (\is_string($value)) {
             return $this->container->resolveEnvPlaceholders($value, true);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveFactoryClassPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveFactoryClassPass.php
index 848da7f2bd..23f535b71d 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveFactoryClassPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveFactoryClassPass.php
@@ -22,7 +22,7 @@ class ResolveFactoryClassPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if ($value instanceof Definition && \is_array($factory = $value->getFactory()) && null === $factory[0]) {
             if (null === $class = $value->getClass()) {
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveHotPathPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveHotPathPass.php
index 5def580589..1b9f4bfce6 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveHotPathPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveHotPathPass.php
@@ -47,7 +47,7 @@ class ResolveHotPathPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if ($value instanceof ArgumentInterface) {
             return $value;
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveInstanceofConditionalsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveInstanceofConditionalsPass.php
index 0b56476c69..f165c9e03f 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveInstanceofConditionalsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveInstanceofConditionalsPass.php
@@ -44,7 +44,7 @@ class ResolveInstanceofConditionalsPass implements CompilerPassInterface
         }
     }
 
-    private function processDefinition(ContainerBuilder $container, $id, Definition $definition)
+    private function processDefinition(ContainerBuilder $container, string $id, Definition $definition)
     {
         $instanceofConditionals = $definition->getInstanceofConditionals();
         $autoconfiguredInstanceof = $definition->isAutoconfigured() ? $container->getAutoconfiguredInstanceof() : [];
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveInvalidReferencesPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveInvalidReferencesPass.php
index ec4b6eec62..d7ebe69eb8 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveInvalidReferencesPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveInvalidReferencesPass.php
@@ -53,7 +53,7 @@ class ResolveInvalidReferencesPass implements CompilerPassInterface
      *
      * @throws RuntimeException When an invalid reference is found
      */
-    private function processValue($value, $rootLevel = 0, $level = 0)
+    private function processValue($value, int $rootLevel = 0, int $level = 0)
     {
         if ($value instanceof ServiceClosureArgument) {
             $value->setValues($this->processValue($value->getValues(), 1, 1));
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveNamedArgumentsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveNamedArgumentsPass.php
index 807fbe7489..1ceb004c17 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveNamedArgumentsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveNamedArgumentsPass.php
@@ -26,7 +26,7 @@ class ResolveNamedArgumentsPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof Definition) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveParameterPlaceHoldersPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveParameterPlaceHoldersPass.php
index 2dec13f15d..91bba7ddb1 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveParameterPlaceHoldersPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveParameterPlaceHoldersPass.php
@@ -58,7 +58,7 @@ class ResolveParameterPlaceHoldersPass extends AbstractRecursivePass
         $this->bag = null;
     }
 
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (\is_string($value)) {
             $v = $this->bag->resolveValue($value);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveReferencesToAliasesPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveReferencesToAliasesPass.php
index bf9ea2b21a..f38dbc79a5 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveReferencesToAliasesPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveReferencesToAliasesPass.php
@@ -42,7 +42,7 @@ class ResolveReferencesToAliasesPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof Reference) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveServiceSubscribersPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveServiceSubscribersPass.php
index 399f349046..518c03d7e7 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveServiceSubscribersPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveServiceSubscribersPass.php
@@ -25,7 +25,7 @@ class ResolveServiceSubscribersPass extends AbstractRecursivePass
 {
     private $serviceLocator;
 
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if ($value instanceof Reference && $this->serviceLocator && \in_array((string) $value, [ContainerInterface::class, ServiceProviderInterface::class], true)) {
             return new Reference($this->serviceLocator);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveTaggedIteratorArgumentPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveTaggedIteratorArgumentPass.php
index a4305722f7..48a034a847 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveTaggedIteratorArgumentPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveTaggedIteratorArgumentPass.php
@@ -25,7 +25,7 @@ class ResolveTaggedIteratorArgumentPass extends AbstractRecursivePass
     /**
      * {@inheritdoc}
      */
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if (!$value instanceof TaggedIteratorArgument) {
             return parent::processValue($value, $isRoot);
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ServiceLocatorTagPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ServiceLocatorTagPass.php
index 424018b7ee..099ed9c342 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ServiceLocatorTagPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ServiceLocatorTagPass.php
@@ -29,7 +29,7 @@ final class ServiceLocatorTagPass extends AbstractRecursivePass
 {
     use PriorityTaggedServiceTrait;
 
-    protected function processValue($value, $isRoot = false)
+    protected function processValue($value, bool $isRoot = false)
     {
         if ($value instanceof ServiceLocatorArgument) {
             if ($value->getTaggedIteratorArgument()) {
@@ -87,11 +87,9 @@ final class ServiceLocatorTagPass extends AbstractRecursivePass
     }
 
     /**
-     * @param ContainerBuilder $container
-     * @param Reference[]      $refMap
-     * @param string|null      $callerId
+     * @param Reference[] $refMap
      */
-    public static function register(ContainerBuilder $container, array $refMap, $callerId = null): Reference
+    public static function register(ContainerBuilder $container, array $refMap, string $callerId = null): Reference
     {
         foreach ($refMap as $id => $ref) {
             if (!$ref instanceof Reference) {