diff --git a/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php b/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
index 4e9504f713..f0c6573d41 100644
--- a/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
+++ b/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
@@ -74,10 +74,8 @@ abstract class AnnotationClassLoader implements LoaderInterface
 
     /**
      * Sets the annotation class to read route properties from.
-     *
-     * @param string $class A fully-qualified class name
      */
-    public function setRouteAnnotationClass($class)
+    public function setRouteAnnotationClass(string $class)
     {
         $this->routeAnnotationClass = $class;
     }
@@ -85,8 +83,7 @@ abstract class AnnotationClassLoader implements LoaderInterface
     /**
      * Loads from annotations from a class.
      *
-     * @param string      $class A class name
-     * @param string|null $type  The resource type
+     * @param string $class A class name
      *
      * @return RouteCollection A RouteCollection instance
      *
@@ -129,7 +126,7 @@ abstract class AnnotationClassLoader implements LoaderInterface
         return $collection;
     }
 
-    protected function addRoute(RouteCollection $collection, $annot, $globals, \ReflectionClass $class, \ReflectionMethod $method)
+    protected function addRoute(RouteCollection $collection, $annot, array $globals, \ReflectionClass $class, \ReflectionMethod $method)
     {
         $name = $annot->getName();
         if (null === $name) {
@@ -217,7 +214,7 @@ abstract class AnnotationClassLoader implements LoaderInterface
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return \is_string($resource) && preg_match('/^(?:\\\\?[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)+$/', $resource) && (!$type || 'annotation' === $type);
     }
@@ -306,7 +303,7 @@ abstract class AnnotationClassLoader implements LoaderInterface
         return $globals;
     }
 
-    private function resetGlobals()
+    private function resetGlobals(): array
     {
         return [
             'path' => null,
@@ -322,7 +319,7 @@ abstract class AnnotationClassLoader implements LoaderInterface
         ];
     }
 
-    protected function createRoute($path, $defaults, $requirements, $options, $host, $schemes, $methods, $condition)
+    protected function createRoute(string $path, array $defaults, array $requirements, array $options, ?string $host, array $schemes, array $methods, ?string $condition)
     {
         return new Route($path, $defaults, $requirements, $options, $host, $schemes, $methods, $condition);
     }
diff --git a/src/Symfony/Component/Routing/Loader/AnnotationFileLoader.php b/src/Symfony/Component/Routing/Loader/AnnotationFileLoader.php
index c6868a6e81..c183d77fc7 100644
--- a/src/Symfony/Component/Routing/Loader/AnnotationFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/AnnotationFileLoader.php
@@ -81,11 +81,9 @@ class AnnotationFileLoader extends FileLoader
     /**
      * Returns the full class name for the first class in the file.
      *
-     * @param string $file A PHP file path
-     *
      * @return string|false Full class name if found, false otherwise
      */
-    protected function findClass($file)
+    protected function findClass(string $file)
     {
         $class = false;
         $namespace = false;
diff --git a/src/Symfony/Component/Routing/Loader/Configurator/RoutingConfigurator.php b/src/Symfony/Component/Routing/Loader/Configurator/RoutingConfigurator.php
index f9c347e81a..ef53d44204 100644
--- a/src/Symfony/Component/Routing/Loader/Configurator/RoutingConfigurator.php
+++ b/src/Symfony/Component/Routing/Loader/Configurator/RoutingConfigurator.php
@@ -33,7 +33,7 @@ class RoutingConfigurator
         $this->file = $file;
     }
 
-    final public function import($resource, $type = null, $ignoreErrors = false): ImportConfigurator
+    final public function import($resource, string $type = null, bool $ignoreErrors = false): ImportConfigurator
     {
         $this->loader->setCurrentDir(\dirname($this->path));
         $imported = $this->loader->import($resource, $type, $ignoreErrors, $this->file);
@@ -49,7 +49,7 @@ class RoutingConfigurator
         return new ImportConfigurator($this->collection, $mergedCollection);
     }
 
-    final public function collection($name = ''): CollectionConfigurator
+    final public function collection(string $name = ''): CollectionConfigurator
     {
         return new CollectionConfigurator($this->collection, $name);
     }
diff --git a/src/Symfony/Component/Routing/Loader/XmlFileLoader.php b/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
index 862cf37691..d694d407d0 100644
--- a/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/XmlFileLoader.php
@@ -69,7 +69,7 @@ class XmlFileLoader extends FileLoader
      *
      * @throws \InvalidArgumentException When the XML is invalid
      */
-    protected function parseNode(RouteCollection $collection, \DOMElement $node, $path, $file)
+    protected function parseNode(RouteCollection $collection, \DOMElement $node, string $path, string $file)
     {
         if (self::NAMESPACE_URI !== $node->namespaceURI) {
             return;
@@ -103,7 +103,7 @@ class XmlFileLoader extends FileLoader
      *
      * @throws \InvalidArgumentException When the XML is invalid
      */
-    protected function parseRoute(RouteCollection $collection, \DOMElement $node, $path)
+    protected function parseRoute(RouteCollection $collection, \DOMElement $node, string $path)
     {
         if ('' === $id = $node->getAttribute('id')) {
             throw new \InvalidArgumentException(sprintf('The <route> element in file "%s" must have an "id" attribute.', $path));
@@ -144,7 +144,7 @@ class XmlFileLoader extends FileLoader
      *
      * @throws \InvalidArgumentException When the XML is invalid
      */
-    protected function parseImport(RouteCollection $collection, \DOMElement $node, $path, $file)
+    protected function parseImport(RouteCollection $collection, \DOMElement $node, string $path, string $file)
     {
         if ('' === $resource = $node->getAttribute('resource')) {
             throw new \InvalidArgumentException(sprintf('The <import> element in file "%s" must have a "resource" attribute.', $path));
@@ -242,7 +242,7 @@ class XmlFileLoader extends FileLoader
      *                                   or when the XML structure is not as expected by the scheme -
      *                                   see validate()
      */
-    protected function loadFile($file)
+    protected function loadFile(string $file)
     {
         return XmlUtils::loadFile($file, __DIR__.static::SCHEME_PATH);
     }
diff --git a/src/Symfony/Component/Routing/Loader/YamlFileLoader.php b/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
index 04868b5f19..0549f50321 100644
--- a/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
+++ b/src/Symfony/Component/Routing/Loader/YamlFileLoader.php
@@ -93,7 +93,7 @@ class YamlFileLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return \is_string($resource) && \in_array(pathinfo($resource, PATHINFO_EXTENSION), ['yml', 'yaml'], true) && (!$type || 'yaml' === $type);
     }
@@ -105,7 +105,7 @@ class YamlFileLoader extends FileLoader
      * @param array  $config Route definition
      * @param string $path   Full path of the YAML file being processed
      */
-    protected function parseRoute(RouteCollection $collection, $name, array $config, $path)
+    protected function parseRoute(RouteCollection $collection, string $name, array $config, string $path)
     {
         $defaults = isset($config['defaults']) ? $config['defaults'] : [];
         $requirements = isset($config['requirements']) ? $config['requirements'] : [];
@@ -157,7 +157,7 @@ class YamlFileLoader extends FileLoader
      * @param string $path   Full path of the YAML file being processed
      * @param string $file   Loaded file name
      */
-    protected function parseImport(RouteCollection $collection, array $config, $path, $file)
+    protected function parseImport(RouteCollection $collection, array $config, string $path, string $file)
     {
         $type = isset($config['type']) ? $config['type'] : null;
         $prefix = isset($config['prefix']) ? $config['prefix'] : '';
@@ -260,7 +260,7 @@ class YamlFileLoader extends FileLoader
      * @throws \InvalidArgumentException If one of the provided config keys is not supported,
      *                                   something is missing or the combination is nonsense
      */
-    protected function validate($config, $name, $path)
+    protected function validate($config, string $name, string $path)
     {
         if (!\is_array($config)) {
             throw new \InvalidArgumentException(sprintf('The definition of "%s" in "%s" must be a YAML array.', $name, $path));
diff --git a/src/Symfony/Component/Routing/Matcher/Dumper/CompiledUrlMatcherTrait.php b/src/Symfony/Component/Routing/Matcher/Dumper/CompiledUrlMatcherTrait.php
index 0528a7b213..a725fd80dc 100644
--- a/src/Symfony/Component/Routing/Matcher/Dumper/CompiledUrlMatcherTrait.php
+++ b/src/Symfony/Component/Routing/Matcher/Dumper/CompiledUrlMatcherTrait.php
@@ -32,7 +32,7 @@ trait CompiledUrlMatcherTrait
     private $dynamicRoutes = [];
     private $checkCondition;
 
-    public function match($pathinfo)
+    public function match(string $pathinfo)
     {
         $allow = $allowSchemes = [];
         if ($ret = $this->doMatch($pathinfo, $allow, $allowSchemes)) {
diff --git a/src/Symfony/Component/Routing/Matcher/TraceableUrlMatcher.php b/src/Symfony/Component/Routing/Matcher/TraceableUrlMatcher.php
index 070fea1523..4565815975 100644
--- a/src/Symfony/Component/Routing/Matcher/TraceableUrlMatcher.php
+++ b/src/Symfony/Component/Routing/Matcher/TraceableUrlMatcher.php
@@ -29,7 +29,7 @@ class TraceableUrlMatcher extends UrlMatcher
 
     protected $traces;
 
-    public function getTraces($pathinfo)
+    public function getTraces(string $pathinfo)
     {
         $this->traces = [];
 
@@ -50,7 +50,7 @@ class TraceableUrlMatcher extends UrlMatcher
         return $traces;
     }
 
-    protected function matchCollection($pathinfo, RouteCollection $routes)
+    protected function matchCollection(string $pathinfo, RouteCollection $routes)
     {
         foreach ($routes as $name => $route) {
             $compiledRoute = $route->compile();
diff --git a/src/Symfony/Component/Routing/Matcher/UrlMatcher.php b/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
index 0d3af972a4..ceadb515fe 100644
--- a/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
+++ b/src/Symfony/Component/Routing/Matcher/UrlMatcher.php
@@ -128,7 +128,7 @@ class UrlMatcher implements UrlMatcherInterface, RequestMatcherInterface
      * @throws ResourceNotFoundException If the resource could not be found
      * @throws MethodNotAllowedException If the resource was found but the request method is not allowed
      */
-    protected function matchCollection($pathinfo, RouteCollection $routes)
+    protected function matchCollection(string $pathinfo, RouteCollection $routes)
     {
         // HEAD and GET are equivalent as per RFC
         if ('HEAD' === $method = $this->context->getMethod()) {
@@ -207,12 +207,9 @@ class UrlMatcher implements UrlMatcherInterface, RequestMatcherInterface
      * in matchers that do not have access to the matched Route instance
      * (like the PHP and Apache matcher dumpers).
      *
-     * @param string $name       The name of the route
-     * @param array  $attributes An array of attributes from the matcher
-     *
      * @return array An array of parameters
      */
-    protected function getAttributes(Route $route, $name, array $attributes)
+    protected function getAttributes(Route $route, string $name, array $attributes)
     {
         $defaults = $route->getDefaults();
         if (isset($defaults['_canonical_route'])) {
@@ -227,12 +224,9 @@ class UrlMatcher implements UrlMatcherInterface, RequestMatcherInterface
     /**
      * Handles specific route requirements.
      *
-     * @param string $pathinfo The path
-     * @param string $name     The route name
-     *
      * @return array The first element represents the status, the second contains additional information
      */
-    protected function handleRouteRequirements($pathinfo, $name, Route $route)
+    protected function handleRouteRequirements(string $pathinfo, string $name, Route $route)
     {
         // expression condition
         if ($route->getCondition() && !$this->getExpressionLanguage()->evaluate($route->getCondition(), ['context' => $this->context, 'request' => $this->request ?: $this->createRequest($pathinfo)])) {
@@ -245,12 +239,9 @@ class UrlMatcher implements UrlMatcherInterface, RequestMatcherInterface
     /**
      * Get merged default parameters.
      *
-     * @param array $params   The parameters
-     * @param array $defaults The defaults
-     *
      * @return array Merged default parameters
      */
-    protected function mergeDefaults($params, $defaults)
+    protected function mergeDefaults(array $params, array $defaults)
     {
         foreach ($params as $key => $value) {
             if (!\is_int($key) && null !== $value) {
@@ -276,7 +267,7 @@ class UrlMatcher implements UrlMatcherInterface, RequestMatcherInterface
     /**
      * @internal
      */
-    protected function createRequest($pathinfo)
+    protected function createRequest(string $pathinfo)
     {
         if (!class_exists('Symfony\Component\HttpFoundation\Request')) {
             return null;
diff --git a/src/Symfony/Component/Routing/RouteCollectionBuilder.php b/src/Symfony/Component/Routing/RouteCollectionBuilder.php
index 92cf7e7938..406e3c0acb 100644
--- a/src/Symfony/Component/Routing/RouteCollectionBuilder.php
+++ b/src/Symfony/Component/Routing/RouteCollectionBuilder.php
@@ -48,15 +48,13 @@ class RouteCollectionBuilder
      *
      *     $routes->import('blog.yml', '/blog');
      *
-     * @param mixed       $resource
-     * @param string|null $prefix
-     * @param string      $type
+     * @param mixed $resource
      *
      * @return self
      *
      * @throws LoaderLoadException
      */
-    public function import($resource, $prefix = '/', $type = null)
+    public function import($resource, string $prefix = '/', string $type = null)
     {
         /** @var RouteCollection[] $collections */
         $collections = $this->load($resource, $type);
@@ -87,13 +85,9 @@ class RouteCollectionBuilder
     /**
      * Adds a route and returns it for future modification.
      *
-     * @param string      $path       The route path
-     * @param string      $controller The route's controller
-     * @param string|null $name       The name to give this route
-     *
      * @return Route
      */
-    public function add($path, $controller, $name = null)
+    public function add(string $path, string $controller, string $name = null)
     {
         $route = new Route($path);
         $route->setDefault('_controller', $controller);
@@ -114,10 +108,8 @@ class RouteCollectionBuilder
 
     /**
      * Add a RouteCollectionBuilder.
-     *
-     * @param string $prefix
      */
-    public function mount($prefix, self $builder)
+    public function mount(string $prefix, self $builder)
     {
         $builder->prefix = trim(trim($prefix), '/');
         $this->routes[] = $builder;
@@ -126,11 +118,9 @@ class RouteCollectionBuilder
     /**
      * Adds a Route object to the builder.
      *
-     * @param string|null $name
-     *
      * @return $this
      */
-    public function addRoute(Route $route, $name = null)
+    public function addRoute(Route $route, string $name = null)
     {
         if (null === $name) {
             // used as a flag to know which routes will need a name later
@@ -145,11 +135,9 @@ class RouteCollectionBuilder
     /**
      * Sets the host on all embedded routes (unless already set).
      *
-     * @param string $pattern
-     *
      * @return $this
      */
-    public function setHost($pattern)
+    public function setHost(?string $pattern)
     {
         $this->host = $pattern;
 
@@ -159,11 +147,9 @@ class RouteCollectionBuilder
     /**
      * Sets a condition on all embedded routes (unless already set).
      *
-     * @param string $condition
-     *
      * @return $this
      */
-    public function setCondition($condition)
+    public function setCondition(?string $condition)
     {
         $this->condition = $condition;
 
@@ -174,12 +160,11 @@ class RouteCollectionBuilder
      * Sets a default value that will be added to all embedded routes (unless that
      * default value is already set).
      *
-     * @param string $key
-     * @param mixed  $value
+     * @param mixed $value
      *
      * @return $this
      */
-    public function setDefault($key, $value)
+    public function setDefault(string $key, $value)
     {
         $this->defaults[$key] = $value;
 
@@ -190,12 +175,11 @@ class RouteCollectionBuilder
      * Sets a requirement that will be added to all embedded routes (unless that
      * requirement is already set).
      *
-     * @param string $key
-     * @param mixed  $regex
+     * @param mixed $regex
      *
      * @return $this
      */
-    public function setRequirement($key, $regex)
+    public function setRequirement(string $key, $regex)
     {
         $this->requirements[$key] = $regex;
 
@@ -206,12 +190,11 @@ class RouteCollectionBuilder
      * Sets an option that will be added to all embedded routes (unless that
      * option is already set).
      *
-     * @param string $key
-     * @param mixed  $value
+     * @param mixed $value
      *
      * @return $this
      */
-    public function setOption($key, $value)
+    public function setOption(string $key, $value)
     {
         $this->options[$key] = $value;
 
diff --git a/src/Symfony/Component/Routing/Tests/Fixtures/CustomXmlFileLoader.php b/src/Symfony/Component/Routing/Tests/Fixtures/CustomXmlFileLoader.php
index b7a02b60b0..727ac07a99 100644
--- a/src/Symfony/Component/Routing/Tests/Fixtures/CustomXmlFileLoader.php
+++ b/src/Symfony/Component/Routing/Tests/Fixtures/CustomXmlFileLoader.php
@@ -19,7 +19,7 @@ use Symfony\Component\Routing\Loader\XmlFileLoader;
  */
 class CustomXmlFileLoader extends XmlFileLoader
 {
-    protected function loadFile($file)
+    protected function loadFile(string $file)
     {
         return XmlUtils::loadFile($file, function () { return true; });
     }
diff --git a/src/Symfony/Component/Routing/Tests/Loader/FileLocatorStub.php b/src/Symfony/Component/Routing/Tests/Loader/FileLocatorStub.php
index 870c3cf4f4..c324592ff8 100644
--- a/src/Symfony/Component/Routing/Tests/Loader/FileLocatorStub.php
+++ b/src/Symfony/Component/Routing/Tests/Loader/FileLocatorStub.php
@@ -6,7 +6,7 @@ use Symfony\Component\Config\FileLocatorInterface;
 
 class FileLocatorStub implements FileLocatorInterface
 {
-    public function locate($name, $currentPath = null, $first = true)
+    public function locate(string $name, string $currentPath = null, bool $first = true)
     {
         if (0 === strpos($name, 'http')) {
             return $name;
diff --git a/src/Symfony/Component/Routing/Tests/Loader/GlobFileLoaderTest.php b/src/Symfony/Component/Routing/Tests/Loader/GlobFileLoaderTest.php
index e4e12b8815..e68d9a08e2 100644
--- a/src/Symfony/Component/Routing/Tests/Loader/GlobFileLoaderTest.php
+++ b/src/Symfony/Component/Routing/Tests/Loader/GlobFileLoaderTest.php
@@ -38,7 +38,7 @@ class GlobFileLoaderTest extends TestCase
 
 class GlobFileLoaderWithoutImport extends GlobFileLoader
 {
-    public function import($resource, $type = null, $ignoreErrors = false, $sourceResource = null)
+    public function import($resource, string $type = null, bool $ignoreErrors = false, string $sourceResource = null)
     {
         return new RouteCollection();
     }
diff --git a/src/Symfony/Component/Routing/Tests/Loader/ObjectLoaderTest.php b/src/Symfony/Component/Routing/Tests/Loader/ObjectLoaderTest.php
index bf94ef34ae..ecb53626fb 100644
--- a/src/Symfony/Component/Routing/Tests/Loader/ObjectLoaderTest.php
+++ b/src/Symfony/Component/Routing/Tests/Loader/ObjectLoaderTest.php
@@ -98,7 +98,7 @@ class TestObjectLoader extends ObjectLoader
 {
     public $loaderMap = [];
 
-    public function supports($resource, $type = null)
+    public function supports($resource, string $type = null)
     {
         return 'service';
     }