From b42de67ed88b80f08e42a96eeffbc3c3793499dc Mon Sep 17 00:00:00 2001
From: Sergei Filatov <sergei.filatov@idt.net>
Date: Mon, 23 Oct 2023 15:04:44 +0300
Subject: [PATCH] added #[\ReturnTypeWillChange]

---
 Slim/App.php                                  | 25 ++++++++++
 Slim/CallableResolver.php                     |  4 ++
 Slim/CallableResolverAwareTrait.php           |  1 +
 Slim/Collection.php                           | 14 ++++++
 Slim/Container.php                            |  4 ++
 Slim/DefaultServicesProvider.php              |  1 +
 Slim/DeferredCallable.php                     |  2 +
 Slim/Exception/InvalidMethodException.php     |  1 +
 Slim/Exception/MethodNotAllowedException.php  |  1 +
 Slim/Exception/SlimException.php              |  2 +
 Slim/Handlers/AbstractError.php               |  3 ++
 Slim/Handlers/AbstractHandler.php             |  1 +
 Slim/Handlers/Error.php                       |  7 +++
 Slim/Handlers/NotAllowed.php                  |  5 ++
 Slim/Handlers/NotFound.php                    |  5 ++
 Slim/Handlers/PhpError.php                    |  6 +++
 Slim/Handlers/Strategies/RequestResponse.php  |  1 +
 .../Strategies/RequestResponseArgs.php        |  1 +
 Slim/Http/Cookies.php                         |  5 ++
 Slim/Http/Environment.php                     |  1 +
 Slim/Http/Headers.php                         | 11 ++++-
 Slim/Http/Message.php                         | 11 +++++
 Slim/Http/NonBufferedBody.php                 | 10 ++++
 Slim/Http/Request.php                         | 46 +++++++++++++++++++
 Slim/Http/Response.php                        | 19 ++++++++
 Slim/Http/Stream.php                          | 18 ++++++++
 Slim/Http/UploadedFile.php                    |  9 ++++
 Slim/Http/Uri.php                             | 26 +++++++++++
 Slim/Interfaces/CallableResolverInterface.php |  1 +
 Slim/Interfaces/CollectionInterface.php       |  5 ++
 Slim/Interfaces/Http/CookiesInterface.php     |  4 ++
 Slim/Interfaces/Http/EnvironmentInterface.php |  1 +
 Slim/Interfaces/Http/HeadersInterface.php     |  1 +
 .../InvocationStrategyInterface.php           |  1 +
 Slim/Interfaces/RouteGroupInterface.php       |  2 +
 Slim/Interfaces/RouteInterface.php            | 12 +++++
 Slim/Interfaces/RouterInterface.php           |  8 ++++
 Slim/MiddlewareAwareTrait.php                 |  3 ++
 Slim/Routable.php                             |  5 ++
 Slim/Route.php                                | 16 +++++++
 Slim/RouteGroup.php                           |  1 +
 Slim/Router.php                               | 20 ++++++++
 42 files changed, 319 insertions(+), 1 deletion(-)

diff --git a/Slim/App.php b/Slim/App.php
index 21cfa5d6..47157f07 100644
--- a/Slim/App.php
+++ b/Slim/App.php
@@ -71,6 +71,7 @@ public function __construct($container = [])
      *
      * @return ContainerInterface
      */
+    #[\ReturnTypeWillChange]
     public function getContainer()
     {
         return $this->container;
@@ -85,6 +86,7 @@ public function getContainer()
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function add($callable)
     {
         return $this->addMiddleware(new DeferredCallable($callable, $this->container));
@@ -101,6 +103,7 @@ public function add($callable)
      *
      * @throws BadMethodCallException
      */
+    #[\ReturnTypeWillChange]
     public function __call($method, $args)
     {
         if ($this->container->has($method)) {
@@ -121,6 +124,7 @@ public function __call($method, $args)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function get($pattern, $callable)
     {
         return $this->map(['GET'], $pattern, $callable);
@@ -134,6 +138,7 @@ public function get($pattern, $callable)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function post($pattern, $callable)
     {
         return $this->map(['POST'], $pattern, $callable);
@@ -147,6 +152,7 @@ public function post($pattern, $callable)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function put($pattern, $callable)
     {
         return $this->map(['PUT'], $pattern, $callable);
@@ -160,6 +166,7 @@ public function put($pattern, $callable)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function patch($pattern, $callable)
     {
         return $this->map(['PATCH'], $pattern, $callable);
@@ -173,6 +180,7 @@ public function patch($pattern, $callable)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function delete($pattern, $callable)
     {
         return $this->map(['DELETE'], $pattern, $callable);
@@ -186,6 +194,7 @@ public function delete($pattern, $callable)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function options($pattern, $callable)
     {
         return $this->map(['OPTIONS'], $pattern, $callable);
@@ -199,6 +208,7 @@ public function options($pattern, $callable)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function any($pattern, $callable)
     {
         return $this->map(['GET', 'POST', 'PUT', 'PATCH', 'DELETE', 'OPTIONS'], $pattern, $callable);
@@ -213,6 +223,7 @@ public function any($pattern, $callable)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function map(array $methods, $pattern, $callable)
     {
         if ($callable instanceof Closure) {
@@ -240,6 +251,7 @@ public function map(array $methods, $pattern, $callable)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function redirect($from, $to, $status = 302)
     {
         $handler = function ($request, ResponseInterface $response) use ($to, $status) {
@@ -261,6 +273,7 @@ public function redirect($from, $to, $status = 302)
      *
      * @return RouteGroupInterface
      */
+    #[\ReturnTypeWillChange]
     public function group($pattern, $callable)
     {
         /** @var RouterInterface $router */
@@ -288,6 +301,7 @@ public function group($pattern, $callable)
      * @throws Exception
      * @throws Throwable
      */
+    #[\ReturnTypeWillChange]
     public function run($silent = false)
     {
         $response = $this->container->get('response');
@@ -338,6 +352,7 @@ public function run($silent = false)
      *
      * @throws ContainerException
      */
+    #[\ReturnTypeWillChange]
     protected function processInvalidMethod(ServerRequestInterface $request, ResponseInterface $response)
     {
         $router = $this->container->get('router');
@@ -373,6 +388,7 @@ protected function processInvalidMethod(ServerRequestInterface $request, Respons
      * @throws Exception
      * @throws Throwable
      */
+    #[\ReturnTypeWillChange]
     public function process(ServerRequestInterface $request, ResponseInterface $response)
     {
         // Ensure basePath is set
@@ -404,6 +420,7 @@ public function process(ServerRequestInterface $request, ResponseInterface $resp
      *
      * @param ResponseInterface $response
      */
+    #[\ReturnTypeWillChange]
     public function respond(ResponseInterface $response)
     {
         // Send response
@@ -484,6 +501,7 @@ public function respond(ResponseInterface $response)
      * @throws MethodNotAllowedException
      * @throws NotFoundException
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(ServerRequestInterface $request, ResponseInterface $response)
     {
         // Get the route info
@@ -540,6 +558,7 @@ public function __invoke(ServerRequestInterface $request, ResponseInterface $res
      * @throws MethodNotAllowedException
      * @throws NotFoundException
      */
+    #[\ReturnTypeWillChange]
     public function subRequest(
         $method,
         $path,
@@ -573,6 +592,7 @@ public function subRequest(
      *
      * @return ServerRequestInterface
      */
+    #[\ReturnTypeWillChange]
     protected function dispatchRouterAndPrepareRoute(ServerRequestInterface $request, RouterInterface $router)
     {
         $routeInfo = $router->dispatch($request);
@@ -604,6 +624,7 @@ protected function dispatchRouterAndPrepareRoute(ServerRequestInterface $request
      *
      * @throws RuntimeException
      */
+    #[\ReturnTypeWillChange]
     protected function finalize(ResponseInterface $response)
     {
         // stop PHP sending a Content-Type automatically
@@ -645,6 +666,7 @@ protected function finalize(ResponseInterface $response)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     protected function isEmptyResponse(ResponseInterface $response)
     {
         if (method_exists($response, 'isEmpty')) {
@@ -661,6 +683,7 @@ protected function isEmptyResponse(ResponseInterface $response)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     protected function isHeadRequest(RequestInterface $request)
     {
         $method = $request->getMethod();
@@ -679,6 +702,7 @@ protected function isHeadRequest(RequestInterface $request)
      *
      * @throws Exception If a handler is needed and not found
      */
+    #[\ReturnTypeWillChange]
     protected function handleException(Exception $e, ServerRequestInterface $request, ResponseInterface $response)
     {
         if ($e instanceof MethodNotAllowedException) {
@@ -718,6 +742,7 @@ protected function handleException(Exception $e, ServerRequestInterface $request
      *
      * @throws Throwable
      */
+    #[\ReturnTypeWillChange]
     protected function handlePhpError(Throwable $e, ServerRequestInterface $request, ResponseInterface $response)
     {
         $handler = 'phpErrorHandler';
diff --git a/Slim/CallableResolver.php b/Slim/CallableResolver.php
index 577e9df2..206c6ba7 100644
--- a/Slim/CallableResolver.php
+++ b/Slim/CallableResolver.php
@@ -45,6 +45,7 @@ public function __construct(ContainerInterface $container)
      * @throws RuntimeException If the callable does not exist
      * @throws RuntimeException If the callable is not resolvable
      */
+    #[\ReturnTypeWillChange]
     public function resolve($toResolve)
     {
         if (is_callable($toResolve)) {
@@ -69,6 +70,7 @@ public function resolve($toResolve)
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     protected function parseCallable($toResolve)
     {
         if (preg_match(self::CALLABLE_PATTERN, $toResolve, $matches)) {
@@ -89,6 +91,7 @@ protected function parseCallable($toResolve)
      *
      * @throws RuntimeException if the callable does not exist
      */
+    #[\ReturnTypeWillChange]
     protected function resolveCallable($class, $method)
     {
         if ($this->container->has($class)) {
@@ -107,6 +110,7 @@ protected function resolveCallable($class, $method)
      *
      * @throws RuntimeException if the callable is not resolvable
      */
+    #[\ReturnTypeWillChange]
     protected function assertCallable($callable)
     {
         if (!is_callable($callable)) {
diff --git a/Slim/CallableResolverAwareTrait.php b/Slim/CallableResolverAwareTrait.php
index cdf7367b..0a1e5630 100644
--- a/Slim/CallableResolverAwareTrait.php
+++ b/Slim/CallableResolverAwareTrait.php
@@ -29,6 +29,7 @@ trait CallableResolverAwareTrait
      *
      * @throws RuntimeException If the string cannot be resolved as a callable
      */
+    #[\ReturnTypeWillChange]
     protected function resolveCallable($callable)
     {
         if (!$this->container instanceof ContainerInterface) {
diff --git a/Slim/Collection.php b/Slim/Collection.php
index 2eaec44a..18adfd4e 100644
--- a/Slim/Collection.php
+++ b/Slim/Collection.php
@@ -37,6 +37,7 @@ public function __construct(array $items = [])
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function set($key, $value)
     {
         $this->data[$key] = $value;
@@ -45,6 +46,7 @@ public function set($key, $value)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function get($key, $default = null)
     {
         return $this->has($key) ? $this->data[$key] : $default;
@@ -53,6 +55,7 @@ public function get($key, $default = null)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function replace(array $items)
     {
         foreach ($items as $key => $value) {
@@ -63,6 +66,7 @@ public function replace(array $items)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function all()
     {
         return $this->data;
@@ -73,6 +77,7 @@ public function all()
      *
      * @return array The collection's source data keys
      */
+    #[\ReturnTypeWillChange]
     public function keys()
     {
         return array_keys($this->data);
@@ -81,6 +86,7 @@ public function keys()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function has($key)
     {
         return array_key_exists($key, $this->data);
@@ -89,6 +95,7 @@ public function has($key)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function remove($key)
     {
         unset($this->data[$key]);
@@ -97,6 +104,7 @@ public function remove($key)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function clear()
     {
         $this->data = [];
@@ -109,6 +117,7 @@ public function clear()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($key)
     {
         return $this->has($key);
@@ -121,6 +130,7 @@ public function offsetExists($key)
      *
      * @return mixed The key's value, or the default value
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($key)
     {
         return $this->get($key);
@@ -132,6 +142,7 @@ public function offsetGet($key)
      * @param string $key   The data key
      * @param mixed  $value The data value
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($key, $value)
     {
         $this->set($key, $value);
@@ -142,6 +153,7 @@ public function offsetSet($key, $value)
      *
      * @param string $key The data key
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($key)
     {
         $this->remove($key);
@@ -152,6 +164,7 @@ public function offsetUnset($key)
      *
      * @return int
      */
+    #[\ReturnTypeWillChange]
     public function count()
     {
         return count($this->data);
@@ -162,6 +175,7 @@ public function count()
      *
      * @return ArrayIterator
      */
+    #[\ReturnTypeWillChange]
     public function getIterator()
     {
         return new ArrayIterator($this->data);
diff --git a/Slim/Container.php b/Slim/Container.php
index 01a592fc..29c1c876 100644
--- a/Slim/Container.php
+++ b/Slim/Container.php
@@ -70,6 +70,7 @@ public function __construct(array $values = [])
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     private function registerDefaultServices($userSettings)
     {
         $defaultSettings = $this->defaultSettings;
@@ -100,6 +101,7 @@ private function registerDefaultServices($userSettings)
      * @throws ContainerValueNotFoundException  No entry was found for this identifier.
      * @throws ContainerExceptionInterface      Error while retrieving the entry.
      */
+    #[\ReturnTypeWillChange]
     public function get($id)
     {
         if (!$this->offsetExists($id)) {
@@ -128,6 +130,7 @@ public function get($id)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     private function exceptionThrownByContainer(InvalidArgumentException $exception)
     {
         $trace = $exception->getTrace()[0];
@@ -143,6 +146,7 @@ private function exceptionThrownByContainer(InvalidArgumentException $exception)
      *
      * @return boolean
      */
+    #[\ReturnTypeWillChange]
     public function has($id)
     {
         return $this->offsetExists($id);
diff --git a/Slim/DefaultServicesProvider.php b/Slim/DefaultServicesProvider.php
index 48a8d6e0..087abf82 100644
--- a/Slim/DefaultServicesProvider.php
+++ b/Slim/DefaultServicesProvider.php
@@ -29,6 +29,7 @@ class DefaultServicesProvider
      *
      * @param Container $container A DI container implementing ArrayAccess and psr/container.
      */
+    #[\ReturnTypeWillChange]
     public function register($container)
     {
         if (!isset($container['environment'])) {
diff --git a/Slim/DeferredCallable.php b/Slim/DeferredCallable.php
index 5f335841..0b3542f3 100644
--- a/Slim/DeferredCallable.php
+++ b/Slim/DeferredCallable.php
@@ -37,6 +37,7 @@ public function __construct($callable, ContainerInterface $container = null)
     /**
      * @return callable|string
      */
+    #[\ReturnTypeWillChange]
     public function getCallable()
     {
         return $this->callable;
@@ -45,6 +46,7 @@ public function getCallable()
     /**
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function __invoke()
     {
         $callable = $this->resolveCallable($this->callable);
diff --git a/Slim/Exception/InvalidMethodException.php b/Slim/Exception/InvalidMethodException.php
index 7bbc3fd8..7e5b006f 100644
--- a/Slim/Exception/InvalidMethodException.php
+++ b/Slim/Exception/InvalidMethodException.php
@@ -30,6 +30,7 @@ public function __construct(ServerRequestInterface $request, $method)
     /**
      * @return ServerRequestInterface
      */
+    #[\ReturnTypeWillChange]
     public function getRequest()
     {
         return $this->request;
diff --git a/Slim/Exception/MethodNotAllowedException.php b/Slim/Exception/MethodNotAllowedException.php
index 20d38248..aee7e155 100644
--- a/Slim/Exception/MethodNotAllowedException.php
+++ b/Slim/Exception/MethodNotAllowedException.php
@@ -31,6 +31,7 @@ public function __construct(ServerRequestInterface $request, ResponseInterface $
     /**
      * @return string[]
      */
+    #[\ReturnTypeWillChange]
     public function getAllowedMethods()
     {
         return $this->allowedMethods;
diff --git a/Slim/Exception/SlimException.php b/Slim/Exception/SlimException.php
index 5b15a4a0..0a883c02 100644
--- a/Slim/Exception/SlimException.php
+++ b/Slim/Exception/SlimException.php
@@ -37,6 +37,7 @@ public function __construct(ServerRequestInterface $request, ResponseInterface $
     /**
      * @return ServerRequestInterface
      */
+    #[\ReturnTypeWillChange]
     public function getRequest()
     {
         return $this->request;
@@ -45,6 +46,7 @@ public function getRequest()
     /**
      * @return ResponseInterface
      */
+    #[\ReturnTypeWillChange]
     public function getResponse()
     {
         return $this->response;
diff --git a/Slim/Handlers/AbstractError.php b/Slim/Handlers/AbstractError.php
index 256062f7..cf510eb8 100644
--- a/Slim/Handlers/AbstractError.php
+++ b/Slim/Handlers/AbstractError.php
@@ -32,6 +32,7 @@ public function __construct($displayErrorDetails = false)
      *
      * @return void
      */
+    #[\ReturnTypeWillChange]
     protected function writeToErrorLog($throwable)
     {
         if ($this->displayErrorDetails) {
@@ -57,6 +58,7 @@ protected function writeToErrorLog($throwable)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderThrowableAsText($throwable)
     {
         $text = sprintf('Type: %s' . PHP_EOL, get_class($throwable));
@@ -89,6 +91,7 @@ protected function renderThrowableAsText($throwable)
      *
      * @param string $message
      */
+    #[\ReturnTypeWillChange]
     protected function logError($message)
     {
         error_log($message);
diff --git a/Slim/Handlers/AbstractHandler.php b/Slim/Handlers/AbstractHandler.php
index 5ace9a0f..2fd2cd6c 100644
--- a/Slim/Handlers/AbstractHandler.php
+++ b/Slim/Handlers/AbstractHandler.php
@@ -34,6 +34,7 @@ abstract class AbstractHandler
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function determineContentType(ServerRequestInterface $request)
     {
         $acceptHeader = $request->getHeaderLine('Accept');
diff --git a/Slim/Handlers/Error.php b/Slim/Handlers/Error.php
index 50ece965..1f123394 100644
--- a/Slim/Handlers/Error.php
+++ b/Slim/Handlers/Error.php
@@ -25,6 +25,7 @@ class Error extends AbstractError
      *
      * @throws UnexpectedValueException
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(ServerRequestInterface $request, ResponseInterface $response, Exception $exception)
     {
         $contentType = $this->determineContentType($request);
@@ -64,6 +65,7 @@ public function __invoke(ServerRequestInterface $request, ResponseInterface $res
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderHtmlErrorMessage(Exception $exception)
     {
         $title = 'Slim Application Error';
@@ -103,6 +105,7 @@ protected function renderHtmlErrorMessage(Exception $exception)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderHtmlException(Exception $exception)
     {
         return $this->renderHtmlExceptionOrError($exception);
@@ -117,6 +120,7 @@ protected function renderHtmlException(Exception $exception)
      *
      * @throws RuntimeException
      */
+    #[\ReturnTypeWillChange]
     protected function renderHtmlExceptionOrError($exception)
     {
         if (!$exception instanceof Exception && !$exception instanceof \Error) {
@@ -156,6 +160,7 @@ protected function renderHtmlExceptionOrError($exception)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderJsonErrorMessage(Exception $exception)
     {
         $error = [
@@ -187,6 +192,7 @@ protected function renderJsonErrorMessage(Exception $exception)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderXmlErrorMessage(Exception $exception)
     {
         $xml = "<error>\n  <message>Slim Application Error</message>\n";
@@ -214,6 +220,7 @@ protected function renderXmlErrorMessage(Exception $exception)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     private function createCdataSection($content)
     {
         return sprintf('<![CDATA[%s]]>', str_replace(']]>', ']]]]><![CDATA[>', $content));
diff --git a/Slim/Handlers/NotAllowed.php b/Slim/Handlers/NotAllowed.php
index 5eba80be..3b80376d 100644
--- a/Slim/Handlers/NotAllowed.php
+++ b/Slim/Handlers/NotAllowed.php
@@ -23,6 +23,7 @@ class NotAllowed extends AbstractHandler
      *
      * @throws UnexpectedValueException
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(ServerRequestInterface $request, ResponseInterface $response, array $methods)
     {
         if ($request->getMethod() === 'OPTIONS') {
@@ -68,6 +69,7 @@ public function __invoke(ServerRequestInterface $request, ResponseInterface $res
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderPlainOptionsMessage($methods)
     {
         $allow = implode(', ', $methods);
@@ -82,6 +84,7 @@ protected function renderPlainOptionsMessage($methods)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderJsonNotAllowedMessage($methods)
     {
         $allow = implode(', ', $methods);
@@ -96,6 +99,7 @@ protected function renderJsonNotAllowedMessage($methods)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderXmlNotAllowedMessage($methods)
     {
         $allow = implode(', ', $methods);
@@ -110,6 +114,7 @@ protected function renderXmlNotAllowedMessage($methods)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderHtmlNotAllowedMessage($methods)
     {
         $allow = implode(', ', $methods);
diff --git a/Slim/Handlers/NotFound.php b/Slim/Handlers/NotFound.php
index f0d013c6..49090d48 100644
--- a/Slim/Handlers/NotFound.php
+++ b/Slim/Handlers/NotFound.php
@@ -22,6 +22,7 @@ class NotFound extends AbstractHandler
      *
      * @throws UnexpectedValueException
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(ServerRequestInterface $request, ResponseInterface $response)
     {
         if ($request->getMethod() === 'OPTIONS') {
@@ -61,6 +62,7 @@ public function __invoke(ServerRequestInterface $request, ResponseInterface $res
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderPlainNotFoundOutput()
     {
         return 'Not found';
@@ -71,6 +73,7 @@ protected function renderPlainNotFoundOutput()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderJsonNotFoundOutput()
     {
         return '{"message":"Not found"}';
@@ -81,6 +84,7 @@ protected function renderJsonNotFoundOutput()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderXmlNotFoundOutput()
     {
         return '<root><message>Not found</message></root>';
@@ -93,6 +97,7 @@ protected function renderXmlNotFoundOutput()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderHtmlNotFoundOutput(ServerRequestInterface $request)
     {
         $homeUrl = (string)($request->getUri()->withPath('')->withQuery('')->withFragment(''));
diff --git a/Slim/Handlers/PhpError.php b/Slim/Handlers/PhpError.php
index 28c74162..839a8f65 100644
--- a/Slim/Handlers/PhpError.php
+++ b/Slim/Handlers/PhpError.php
@@ -24,6 +24,7 @@ class PhpError extends AbstractError
      *
      * @throws UnexpectedValueException
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(ServerRequestInterface $request, ResponseInterface $response, Throwable $error)
     {
         $contentType = $this->determineContentType($request);
@@ -62,6 +63,7 @@ public function __invoke(ServerRequestInterface $request, ResponseInterface $res
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderHtmlErrorMessage(Throwable $error)
     {
         $title = 'Slim Application Error';
@@ -99,6 +101,7 @@ protected function renderHtmlErrorMessage(Throwable $error)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderHtmlError(Throwable $error)
     {
         $html = sprintf('<div><strong>Type:</strong> %s</div>', get_class($error));
@@ -134,6 +137,7 @@ protected function renderHtmlError(Throwable $error)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderJsonErrorMessage(Throwable $error)
     {
         $json = [
@@ -165,6 +169,7 @@ protected function renderJsonErrorMessage(Throwable $error)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function renderXmlErrorMessage(Throwable $error)
     {
         $xml = "<error>\n  <message>Slim Application Error</message>\n";
@@ -192,6 +197,7 @@ protected function renderXmlErrorMessage(Throwable $error)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     private function createCdataSection($content)
     {
         return sprintf('<![CDATA[%s]]>', str_replace(']]>', ']]]]><![CDATA[>', $content));
diff --git a/Slim/Handlers/Strategies/RequestResponse.php b/Slim/Handlers/Strategies/RequestResponse.php
index d91b05ae..4d0d804e 100644
--- a/Slim/Handlers/Strategies/RequestResponse.php
+++ b/Slim/Handlers/Strategies/RequestResponse.php
@@ -27,6 +27,7 @@ class RequestResponse implements InvocationStrategyInterface
      *
      * @return ResponseInterface
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(
         callable $callable,
         ServerRequestInterface $request,
diff --git a/Slim/Handlers/Strategies/RequestResponseArgs.php b/Slim/Handlers/Strategies/RequestResponseArgs.php
index d0729145..92db3dc9 100644
--- a/Slim/Handlers/Strategies/RequestResponseArgs.php
+++ b/Slim/Handlers/Strategies/RequestResponseArgs.php
@@ -28,6 +28,7 @@ class RequestResponseArgs implements InvocationStrategyInterface
      *
      * @return ResponseInterface
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(
         callable $callable,
         ServerRequestInterface $request,
diff --git a/Slim/Http/Cookies.php b/Slim/Http/Cookies.php
index db73a7d8..05a06a42 100644
--- a/Slim/Http/Cookies.php
+++ b/Slim/Http/Cookies.php
@@ -55,6 +55,7 @@ public function __construct(array $cookies = [])
      *
      * @param array $settings
      */
+    #[\ReturnTypeWillChange]
     public function setDefaults(array $settings)
     {
         $this->defaults = array_replace($this->defaults, $settings);
@@ -71,6 +72,7 @@ public function get($name, $default = null)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function set($name, $value)
     {
         if (!is_array($value)) {
@@ -82,6 +84,7 @@ public function set($name, $value)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function toHeaders()
     {
         $headers = [];
@@ -100,6 +103,7 @@ public function toHeaders()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     protected function toHeader($name, array $properties)
     {
         $result = urlencode($name) . '=' . urlencode($properties['value']);
@@ -147,6 +151,7 @@ protected function toHeader($name, array $properties)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public static function parseHeader($header)
     {
         if (is_array($header) === true) {
diff --git a/Slim/Http/Environment.php b/Slim/Http/Environment.php
index 11089d98..39fa65e4 100644
--- a/Slim/Http/Environment.php
+++ b/Slim/Http/Environment.php
@@ -20,6 +20,7 @@ class Environment extends Collection implements EnvironmentInterface
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public static function mock(array $settings = [])
     {
         //Validates if default protocol is HTTPS to set default port 443
diff --git a/Slim/Http/Headers.php b/Slim/Http/Headers.php
index f2eec7ce..cece701a 100644
--- a/Slim/Http/Headers.php
+++ b/Slim/Http/Headers.php
@@ -44,6 +44,7 @@ class Headers extends Collection implements HeadersInterface
      *
      * @return self
      */
+    #[\ReturnTypeWillChange]
     public static function createFromEnvironment(Environment $environment)
     {
         $data = [];
@@ -67,7 +68,7 @@ public static function createFromEnvironment(Environment $environment)
      *
      * @return Environment
      */
-
+    #[\ReturnTypeWillChange]
     public static function determineAuthorization(Environment $environment)
     {
         $authorization = $environment->get('HTTP_AUTHORIZATION');
@@ -94,6 +95,7 @@ public static function determineAuthorization(Environment $environment)
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function all()
     {
         $all = parent::all();
@@ -114,6 +116,7 @@ public function all()
      * @param string       $key   The case-insensitive header name
      * @param array|string $value The header value
      */
+    #[\ReturnTypeWillChange]
     public function set($key, $value)
     {
         if (!is_array($value)) {
@@ -133,6 +136,7 @@ public function set($key, $value)
      *
      * @return string[]
      */
+    #[\ReturnTypeWillChange]
     public function get($key, $default = null)
     {
         if ($this->has($key)) {
@@ -150,6 +154,7 @@ public function get($key, $default = null)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getOriginalKey($key, $default = null)
     {
         if ($this->has($key)) {
@@ -162,6 +167,7 @@ public function getOriginalKey($key, $default = null)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function add($key, $value)
     {
         $oldValues = $this->get($key, []);
@@ -176,6 +182,7 @@ public function add($key, $value)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function has($key)
     {
         return parent::has($this->normalizeKey($key));
@@ -186,6 +193,7 @@ public function has($key)
      *
      * @param  string $key The case-insensitive header name
      */
+    #[\ReturnTypeWillChange]
     public function remove($key)
     {
         parent::remove($this->normalizeKey($key));
@@ -194,6 +202,7 @@ public function remove($key)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function normalizeKey($key)
     {
         $key = strtr(strtolower($key), '_', '-');
diff --git a/Slim/Http/Message.php b/Slim/Http/Message.php
index 0dc7b4d6..442cef57 100644
--- a/Slim/Http/Message.php
+++ b/Slim/Http/Message.php
@@ -64,6 +64,7 @@ public function __set($name, $value)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getProtocolVersion()
     {
         return $this->protocolVersion;
@@ -85,6 +86,7 @@ public function getProtocolVersion()
      *
      * @throws InvalidArgumentException if the http version is an invalid number
      */
+    #[\ReturnTypeWillChange]
     public function withProtocolVersion($version)
     {
         if (!isset(self::$validProtocolVersions[$version])) {
@@ -125,6 +127,7 @@ public function withProtocolVersion($version)
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function getHeaders()
     {
         return $this->headers->all();
@@ -140,6 +143,7 @@ public function getHeaders()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function hasHeader($name)
     {
         return $this->headers->has($name);
@@ -158,6 +162,7 @@ public function hasHeader($name)
      *
      * @return string[]
      */
+    #[\ReturnTypeWillChange]
     public function getHeader($name)
     {
         return $this->headers->get($name, []);
@@ -181,6 +186,7 @@ public function getHeader($name)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getHeaderLine($name)
     {
         return implode(',', $this->headers->get($name, []));
@@ -201,6 +207,7 @@ public function getHeaderLine($name)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withHeader($name, $value)
     {
         $clone = clone $this;
@@ -225,6 +232,7 @@ public function withHeader($name, $value)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withAddedHeader($name, $value)
     {
         $clone = clone $this;
@@ -250,6 +258,7 @@ public function withAddedHeader($name, $value)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withoutHeader($name)
     {
         $clone = clone $this;
@@ -267,6 +276,7 @@ public function withoutHeader($name)
      *
      * @return StreamInterface Returns the body as a stream.
      */
+    #[\ReturnTypeWillChange]
     public function getBody()
     {
         return $this->body;
@@ -285,6 +295,7 @@ public function getBody()
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withBody(StreamInterface $body)
     {
         $clone = clone $this;
diff --git a/Slim/Http/NonBufferedBody.php b/Slim/Http/NonBufferedBody.php
index 352ff590..c57815a0 100644
--- a/Slim/Http/NonBufferedBody.php
+++ b/Slim/Http/NonBufferedBody.php
@@ -41,6 +41,7 @@ public function detach()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function getSize()
     {
         return null;
@@ -49,6 +50,7 @@ public function getSize()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function tell()
     {
         return 0;
@@ -57,6 +59,7 @@ public function tell()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function eof()
     {
         return true;
@@ -65,6 +68,7 @@ public function eof()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function isSeekable()
     {
         return false;
@@ -73,6 +77,7 @@ public function isSeekable()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function seek($offset, $whence = SEEK_SET)
     {
     }
@@ -87,6 +92,7 @@ public function rewind()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function isWritable()
     {
         return true;
@@ -95,6 +101,7 @@ public function isWritable()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function write($string)
     {
         $buffered = '';
@@ -112,6 +119,7 @@ public function write($string)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function isReadable()
     {
         return false;
@@ -120,6 +128,7 @@ public function isReadable()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function read($length)
     {
         return '';
@@ -128,6 +137,7 @@ public function read($length)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function getContents()
     {
         return '';
diff --git a/Slim/Http/Request.php b/Slim/Http/Request.php
index 1ae17716..e527b243 100644
--- a/Slim/Http/Request.php
+++ b/Slim/Http/Request.php
@@ -131,6 +131,7 @@ class Request extends Message implements ServerRequestInterface
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public static function createFromEnvironment(Environment $environment)
     {
         $method = $environment['REQUEST_METHOD'];
@@ -257,6 +258,7 @@ public function __clone()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getMethod()
     {
         if ($this->method === null) {
@@ -287,6 +289,7 @@ public function getMethod()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getOriginalMethod()
     {
         return $this->originalMethod;
@@ -309,6 +312,7 @@ public function getOriginalMethod()
      *
      * @throws InvalidArgumentException for invalid HTTP methods.
      */
+    #[\ReturnTypeWillChange]
     public function withMethod($method)
     {
         $method = $this->filterMethod($method);
@@ -328,6 +332,7 @@ public function withMethod($method)
      *
      * @throws InvalidArgumentException on invalid HTTP method.
      */
+    #[\ReturnTypeWillChange]
     protected function filterMethod($method)
     {
         if ($method === null) {
@@ -358,6 +363,7 @@ protected function filterMethod($method)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isMethod($method)
     {
         return $this->getMethod() === $method;
@@ -370,6 +376,7 @@ public function isMethod($method)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isGet()
     {
         return $this->isMethod('GET');
@@ -382,6 +389,7 @@ public function isGet()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isPost()
     {
         return $this->isMethod('POST');
@@ -394,6 +402,7 @@ public function isPost()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isPut()
     {
         return $this->isMethod('PUT');
@@ -406,6 +415,7 @@ public function isPut()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isPatch()
     {
         return $this->isMethod('PATCH');
@@ -418,6 +428,7 @@ public function isPatch()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isDelete()
     {
         return $this->isMethod('DELETE');
@@ -430,6 +441,7 @@ public function isDelete()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isHead()
     {
         return $this->isMethod('HEAD');
@@ -442,6 +454,7 @@ public function isHead()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isOptions()
     {
         return $this->isMethod('OPTIONS');
@@ -454,6 +467,7 @@ public function isOptions()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isXhr()
     {
         return $this->getHeaderLine('X-Requested-With') === 'XMLHttpRequest';
@@ -475,6 +489,7 @@ public function isXhr()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getRequestTarget()
     {
         if ($this->requestTarget) {
@@ -523,6 +538,7 @@ public function getRequestTarget()
      *
      * @throws InvalidArgumentException if the request target is invalid
      */
+    #[\ReturnTypeWillChange]
     public function withRequestTarget($requestTarget)
     {
         if (preg_match('#\s#', $requestTarget)) {
@@ -545,6 +561,7 @@ public function withRequestTarget($requestTarget)
      *
      * @return UriInterface
      */
+    #[\ReturnTypeWillChange]
     public function getUri()
     {
         return $this->uri;
@@ -582,6 +599,7 @@ public function getUri()
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withUri(UriInterface $uri, $preserveHost = false)
     {
         $clone = clone $this;
@@ -607,6 +625,7 @@ public function withUri(UriInterface $uri, $preserveHost = false)
      *
      * @return string|null
      */
+    #[\ReturnTypeWillChange]
     public function getContentType()
     {
         $result = $this->getHeader('Content-Type');
@@ -621,6 +640,7 @@ public function getContentType()
      *
      * @return string|null
      */
+    #[\ReturnTypeWillChange]
     public function getMediaType()
     {
         $contentType = $this->getContentType();
@@ -640,6 +660,7 @@ public function getMediaType()
      *
      * @return string[]
      */
+    #[\ReturnTypeWillChange]
     public function getMediaTypeParams()
     {
         $contentType = $this->getContentType();
@@ -663,6 +684,7 @@ public function getMediaTypeParams()
      *
      * @return string|null
      */
+    #[\ReturnTypeWillChange]
     public function getContentCharset()
     {
         $mediaTypeParams = $this->getMediaTypeParams();
@@ -680,6 +702,7 @@ public function getContentCharset()
      *
      * @return int|null
      */
+    #[\ReturnTypeWillChange]
     public function getContentLength()
     {
         $result = $this->headers->get('Content-Length');
@@ -696,6 +719,7 @@ public function getContentLength()
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function getCookieParams()
     {
         return $this->cookies;
@@ -711,6 +735,7 @@ public function getCookieParams()
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function getCookieParam($key, $default = null)
     {
         $cookies = $this->getCookieParams();
@@ -740,6 +765,7 @@ public function getCookieParam($key, $default = null)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withCookieParams(array $cookies)
     {
         $clone = clone $this;
@@ -760,6 +786,7 @@ public function withCookieParams(array $cookies)
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function getQueryParams()
     {
         if (is_array($this->queryParams)) {
@@ -798,6 +825,7 @@ public function getQueryParams()
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withQueryParams(array $query)
     {
         $clone = clone $this;
@@ -817,6 +845,7 @@ public function withQueryParams(array $query)
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function getUploadedFiles()
     {
         return $this->uploadedFiles;
@@ -835,6 +864,7 @@ public function getUploadedFiles()
      *
      * @throws InvalidArgumentException if an invalid structure is provided.
      */
+    #[\ReturnTypeWillChange]
     public function withUploadedFiles(array $uploadedFiles)
     {
         $clone = clone $this;
@@ -852,6 +882,7 @@ public function withUploadedFiles(array $uploadedFiles)
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function getServerParams()
     {
         return $this->serverParams;
@@ -867,6 +898,7 @@ public function getServerParams()
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function getServerParam($key, $default = null)
     {
         $serverParams = $this->getServerParams();
@@ -885,6 +917,7 @@ public function getServerParam($key, $default = null)
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     public function getAttributes()
     {
         return $this->attributes->all();
@@ -907,6 +940,7 @@ public function getAttributes()
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function getAttribute($name, $default = null)
     {
         return $this->attributes->get($name, $default);
@@ -929,6 +963,7 @@ public function getAttribute($name, $default = null)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withAttribute($name, $value)
     {
         $clone = clone $this;
@@ -953,6 +988,7 @@ public function withAttribute($name, $value)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withAttributes(array $attributes)
     {
         $clone = clone $this;
@@ -977,6 +1013,7 @@ public function withAttributes(array $attributes)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withoutAttribute($name)
     {
         $clone = clone $this;
@@ -1001,6 +1038,7 @@ public function withoutAttribute($name)
      *
      * @throws RuntimeException if the request body media type parser returns an invalid value
      */
+    #[\ReturnTypeWillChange]
     public function getParsedBody()
     {
         if ($this->bodyParsed !== false) {
@@ -1067,6 +1105,7 @@ public function getParsedBody()
      * @throws InvalidArgumentException if an unsupported argument type is
      *     provided.
      */
+    #[\ReturnTypeWillChange]
     public function withParsedBody($data)
     {
         if (!is_null($data) && !is_object($data) && !is_array($data)) {
@@ -1086,6 +1125,7 @@ public function withParsedBody($data)
      *
      * @return $this
      */
+    #[\ReturnTypeWillChange]
     public function reparseBody()
     {
         $this->bodyParsed = false;
@@ -1101,6 +1141,7 @@ public function reparseBody()
      * @param string   $mediaType A HTTP media type (excluding content-type params).
      * @param callable $callable  A callable that returns parsed contents for media type.
      */
+    #[\ReturnTypeWillChange]
     public function registerMediaTypeParser($mediaType, callable $callable)
     {
         if ($callable instanceof Closure) {
@@ -1119,6 +1160,7 @@ public function registerMediaTypeParser($mediaType, callable $callable)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function getParam($key, $default = null)
     {
         $postParams = $this->getParsedBody();
@@ -1145,6 +1187,7 @@ public function getParam($key, $default = null)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function getParsedBodyParam($key, $default = null)
     {
         $postParams = $this->getParsedBody();
@@ -1168,6 +1211,7 @@ public function getParsedBodyParam($key, $default = null)
      *
      * @return mixed
      */
+    #[\ReturnTypeWillChange]
     public function getQueryParam($key, $default = null)
     {
         $getParams = $this->getQueryParams();
@@ -1188,6 +1232,7 @@ public function getQueryParam($key, $default = null)
      *
      * @return mixed[]
      */
+    #[\ReturnTypeWillChange]
     public function getParams(array $only = null)
     {
         $params = $this->getQueryParams();
@@ -1209,6 +1254,7 @@ public function getParams(array $only = null)
         return $params;
     }
 
+    #[\ReturnTypeWillChange]
     private static function disableXmlEntityLoader($disable)
     {
         if (\LIBXML_VERSION >= 20900) {
diff --git a/Slim/Http/Response.php b/Slim/Http/Response.php
index 4f572240..1f8e4aa7 100644
--- a/Slim/Http/Response.php
+++ b/Slim/Http/Response.php
@@ -158,6 +158,7 @@ public function __clone()
      *
      * @return int
      */
+    #[\ReturnTypeWillChange]
     public function getStatusCode()
     {
         return $this->status;
@@ -186,6 +187,7 @@ public function getStatusCode()
      *
      * @throws InvalidArgumentException For invalid status code arguments.
      */
+    #[\ReturnTypeWillChange]
     public function withStatus($code, $reasonPhrase = '')
     {
         $code = $this->filterStatus($code);
@@ -218,6 +220,7 @@ public function withStatus($code, $reasonPhrase = '')
      *
      * @throws InvalidArgumentException If an invalid HTTP status code is provided.
      */
+    #[\ReturnTypeWillChange]
     protected function filterStatus($status)
     {
         if (!is_integer($status) ||
@@ -244,6 +247,7 @@ protected function filterStatus($status)
      *
      * @return string Reason phrase; must return an empty string if none present.
      */
+    #[\ReturnTypeWillChange]
     public function getReasonPhrase()
     {
         if ($this->reasonPhrase) {
@@ -268,6 +272,7 @@ public function getReasonPhrase()
      *
      * @throws InvalidArgumentException For invalid header names or values.
      */
+    #[\ReturnTypeWillChange]
     public function withHeader($name, $value)
     {
         $clone = clone $this;
@@ -295,6 +300,7 @@ public function withHeader($name, $value)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function write($data)
     {
         $this->getBody()->write($data);
@@ -315,6 +321,7 @@ public function write($data)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withRedirect($url, $status = null)
     {
         $responseWithRedirect = $this->withHeader('Location', (string)$url);
@@ -346,6 +353,7 @@ public function withRedirect($url, $status = null)
      *
      * @throws RuntimeException
      */
+    #[\ReturnTypeWillChange]
     public function withJson($data, $status = null, $encodingOptions = 0)
     {
         $response = $this->withBody(new Body(fopen('php://temp', 'r+')));
@@ -370,6 +378,7 @@ public function withJson($data, $status = null, $encodingOptions = 0)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isEmpty()
     {
         return in_array(
@@ -385,6 +394,7 @@ public function isEmpty()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isInformational()
     {
         return $this->getStatusCode() >= StatusCode::HTTP_CONTINUE && $this->getStatusCode() < StatusCode::HTTP_OK;
@@ -397,6 +407,7 @@ public function isInformational()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isOk()
     {
         return $this->getStatusCode() === StatusCode::HTTP_OK;
@@ -409,6 +420,7 @@ public function isOk()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isSuccessful()
     {
         return $this->getStatusCode() >= StatusCode::HTTP_OK &&
@@ -422,6 +434,7 @@ public function isSuccessful()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isRedirect()
     {
         return in_array(
@@ -443,6 +456,7 @@ public function isRedirect()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isRedirection()
     {
         return $this->getStatusCode() >= StatusCode::HTTP_MULTIPLE_CHOICES &&
@@ -456,6 +470,7 @@ public function isRedirection()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isForbidden()
     {
         return $this->getStatusCode() === StatusCode::HTTP_FORBIDDEN;
@@ -468,6 +483,7 @@ public function isForbidden()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isNotFound()
     {
         return $this->getStatusCode() === StatusCode::HTTP_NOT_FOUND;
@@ -480,6 +496,7 @@ public function isNotFound()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isBadRequest()
     {
         return $this->getStatusCode() === StatusCode::HTTP_BAD_REQUEST;
@@ -492,6 +509,7 @@ public function isBadRequest()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isClientError()
     {
         return $this->getStatusCode() >= StatusCode::HTTP_BAD_REQUEST &&
@@ -505,6 +523,7 @@ public function isClientError()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isServerError()
     {
         return $this->getStatusCode() >= StatusCode::HTTP_INTERNAL_SERVER_ERROR && $this->getStatusCode() < 600;
diff --git a/Slim/Http/Stream.php b/Slim/Http/Stream.php
index f405dc71..b930b815 100644
--- a/Slim/Http/Stream.php
+++ b/Slim/Http/Stream.php
@@ -108,6 +108,7 @@ public function __construct($stream)
      *     provided. Returns a specific key value if a key is provided and the
      *     value is found, or null if the key is not found.
      */
+    #[\ReturnTypeWillChange]
     public function getMetadata($key = null)
     {
         $this->meta = stream_get_meta_data($this->stream);
@@ -125,6 +126,7 @@ public function getMetadata($key = null)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     protected function isAttached()
     {
         return is_resource($this->stream);
@@ -139,6 +141,7 @@ protected function isAttached()
      *
      * @throws InvalidArgumentException If argument is not a valid PHP resource.
      */
+    #[\ReturnTypeWillChange]
     protected function attach($newStream)
     {
         if (is_resource($newStream) === false) {
@@ -159,6 +162,7 @@ protected function attach($newStream)
      *
      * @return resource|null Underlying PHP stream, if any
      */
+    #[\ReturnTypeWillChange]
     public function detach()
     {
         $oldResource = $this->stream;
@@ -188,6 +192,7 @@ public function detach()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function __toString()
     {
         if (!$this->isAttached()) {
@@ -205,6 +210,7 @@ public function __toString()
     /**
      * Closes the stream and any underlying resources.
      */
+    #[\ReturnTypeWillChange]
     public function close()
     {
         if ($this->isAttached() === true) {
@@ -223,6 +229,7 @@ public function close()
      *
      * @return int|null Returns the size in bytes if known, or null if unknown.
      */
+    #[\ReturnTypeWillChange]
     public function getSize()
     {
         if (!$this->size && $this->isAttached() === true) {
@@ -240,6 +247,7 @@ public function getSize()
      *
      * @throws RuntimeException on error.
      */
+    #[\ReturnTypeWillChange]
     public function tell()
     {
         if (!$this->isAttached() || ($position = ftell($this->stream)) === false || $this->isPipe()) {
@@ -254,6 +262,7 @@ public function tell()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function eof()
     {
         return $this->isAttached() ? feof($this->stream) : true;
@@ -264,6 +273,7 @@ public function eof()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isReadable()
     {
         if ($this->readable === null) {
@@ -291,6 +301,7 @@ public function isReadable()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isWritable()
     {
         if ($this->writable === null) {
@@ -314,6 +325,7 @@ public function isWritable()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isSeekable()
     {
         if ($this->seekable === null) {
@@ -341,6 +353,7 @@ public function isSeekable()
      *
      * @throws RuntimeException If stream is not seekable
      */
+    #[\ReturnTypeWillChange]
     public function seek($offset, $whence = SEEK_SET)
     {
         // Note that fseek returns 0 on success!
@@ -361,6 +374,7 @@ public function seek($offset, $whence = SEEK_SET)
      *
      * @throws RuntimeException on failure.
      */
+    #[\ReturnTypeWillChange]
     public function rewind()
     {
         if (!$this->isSeekable() || rewind($this->stream) === false) {
@@ -379,6 +393,7 @@ public function rewind()
      *
      * @throws RuntimeException if an error occurs.
      */
+    #[\ReturnTypeWillChange]
     public function read($length)
     {
         if (!$this->isReadable() || ($data = fread($this->stream, $length)) === false) {
@@ -397,6 +412,7 @@ public function read($length)
      *
      * @throws RuntimeException If stream is not writable
      */
+    #[\ReturnTypeWillChange]
     public function write($string)
     {
         if (!$this->isWritable() || ($written = fwrite($this->stream, $string)) === false) {
@@ -416,6 +432,7 @@ public function write($string)
      *
      * @throws RuntimeException If stream is not readable
      */
+    #[\ReturnTypeWillChange]
     public function getContents()
     {
         if (!$this->isReadable() || ($contents = stream_get_contents($this->stream)) === false) {
@@ -430,6 +447,7 @@ public function getContents()
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function isPipe()
     {
         if ($this->isPipe === null) {
diff --git a/Slim/Http/UploadedFile.php b/Slim/Http/UploadedFile.php
index 401440db..f7a0021d 100644
--- a/Slim/Http/UploadedFile.php
+++ b/Slim/Http/UploadedFile.php
@@ -87,6 +87,7 @@ class UploadedFile implements UploadedFileInterface
      *
      * @return array|null
      */
+    #[\ReturnTypeWillChange]
     public static function createFromEnvironment(Environment $env)
     {
         if (is_array($env['slim.files']) && $env->has('slim.files')) {
@@ -107,6 +108,7 @@ public static function createFromEnvironment(Environment $env)
      *
      * @return array
      */
+    #[\ReturnTypeWillChange]
     private static function parseUploadedFiles(array $uploadedFiles)
     {
         $parsed = [];
@@ -154,6 +156,7 @@ private static function parseUploadedFiles(array $uploadedFiles)
      * @param int         $error The UPLOAD_ERR_XXX code representing the status of the upload.
      * @param bool        $sapi Indicates if the upload is in a SAPI environment.
      */
+    #[\ReturnTypeWillChange]
     public function __construct($file, $name = null, $type = null, $size = null, $error = UPLOAD_ERR_OK, $sapi = false)
     {
         $this->file = $file;
@@ -180,6 +183,7 @@ public function __construct($file, $name = null, $type = null, $size = null, $er
      *
      * @throws RuntimeException in cases when no stream is available or can be created.
      */
+    #[\ReturnTypeWillChange]
     public function getStream()
     {
         if ($this->moved) {
@@ -225,6 +229,7 @@ public function getStream()
      * @throws InvalidArgumentException If the $path specified is invalid.
      * @throws RuntimeException On any error during the move operation or on the second subsequent call to the method.
      */
+    #[\ReturnTypeWillChange]
     public function moveTo($targetPath)
     {
         if ($this->moved) {
@@ -275,6 +280,7 @@ public function moveTo($targetPath)
      *
      * @return int
      */
+    #[\ReturnTypeWillChange]
     public function getError()
     {
         return $this->error;
@@ -292,6 +298,7 @@ public function getError()
      *
      * @return string|null
      */
+    #[\ReturnTypeWillChange]
     public function getClientFilename()
     {
         return $this->name;
@@ -309,6 +316,7 @@ public function getClientFilename()
      *
      * @return string|null
      */
+    #[\ReturnTypeWillChange]
     public function getClientMediaType()
     {
         return $this->type;
@@ -323,6 +331,7 @@ public function getClientMediaType()
      *
      * @return int|null
      */
+    #[\ReturnTypeWillChange]
     public function getSize()
     {
         return $this->size;
diff --git a/Slim/Http/Uri.php b/Slim/Http/Uri.php
index b5181bae..fc392304 100644
--- a/Slim/Http/Uri.php
+++ b/Slim/Http/Uri.php
@@ -132,6 +132,7 @@ public function __construct(
      *
      * @return self
      */
+    #[\ReturnTypeWillChange]
     public static function createFromString($uri)
     {
         if (!is_string($uri) && (!is_object($uri) || !method_exists($uri, '__toString'))) {
@@ -158,6 +159,7 @@ public static function createFromString($uri)
      *
      * @return self
      */
+    #[\ReturnTypeWillChange]
     public static function createFromEnvironment(Environment $env)
     {
         // Scheme
@@ -246,6 +248,7 @@ public static function createFromEnvironment(Environment $env)
      *
      * @return string The URI scheme.
      */
+    #[\ReturnTypeWillChange]
     public function getScheme()
     {
         return $this->scheme;
@@ -268,6 +271,7 @@ public function getScheme()
      *
      * @throws InvalidArgumentException for invalid or unsupported schemes.
      */
+    #[\ReturnTypeWillChange]
     public function withScheme($scheme)
     {
         $scheme = $this->filterScheme($scheme);
@@ -286,6 +290,7 @@ public function withScheme($scheme)
      * @throws InvalidArgumentException If the Uri scheme is not a string.
      * @throws InvalidArgumentException If Uri scheme is not "", "https", or "http".
      */
+    #[\ReturnTypeWillChange]
     protected function filterScheme($scheme)
     {
         static $valid = [
@@ -325,6 +330,7 @@ protected function filterScheme($scheme)
      *
      * @return string The URI authority, in "[user-info@]host[:port]" format.
      */
+    #[\ReturnTypeWillChange]
     public function getAuthority()
     {
         $userInfo = $this->getUserInfo();
@@ -349,6 +355,7 @@ public function getAuthority()
      *
      * @return string The URI user information, in "username[:password]" format.
      */
+    #[\ReturnTypeWillChange]
     public function getUserInfo()
     {
         return (isset($this->user) ? $this->user : '') . ($this->password !== '' ? ':' . $this->password : '');
@@ -369,6 +376,7 @@ public function getUserInfo()
      *
      * @return self A new instance with the specified user information.
      */
+    #[\ReturnTypeWillChange]
     public function withUserInfo($user, $password = null)
     {
         $clone = clone $this;
@@ -389,6 +397,7 @@ public function withUserInfo($user, $password = null)
      *
      * @return string The percent-encoded query string.
      */
+    #[\ReturnTypeWillChange]
     protected function filterUserInfo($query)
     {
         return preg_replace_callback(
@@ -412,6 +421,7 @@ function ($match) {
      *
      * @return string The URI host.
      */
+    #[\ReturnTypeWillChange]
     public function getHost()
     {
         return isset($this->host) ? $this->host : '';
@@ -429,6 +439,7 @@ public function getHost()
      *
      * @return self A new instance with the specified host.
      */
+    #[\ReturnTypeWillChange]
     public function withHost($host)
     {
         $clone = clone $this;
@@ -452,6 +463,7 @@ public function withHost($host)
      *
      * @return null|int The URI port.
      */
+    #[\ReturnTypeWillChange]
     public function getPort()
     {
         return $this->port && !$this->hasStandardPort() ? $this->port : null;
@@ -474,6 +486,7 @@ public function getPort()
      *
      * @return self A new instance with the specified port.
      */
+    #[\ReturnTypeWillChange]
     public function withPort($port)
     {
         $port = $this->filterPort($port);
@@ -488,6 +501,7 @@ public function withPort($port)
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     protected function hasStandardPort()
     {
         return ($this->scheme === 'http' && $this->port === 80) || ($this->scheme === 'https' && $this->port === 443);
@@ -501,6 +515,7 @@ protected function hasStandardPort()
      *
      * @throws InvalidArgumentException If the port is invalid.
      */
+    #[\ReturnTypeWillChange]
     protected function filterPort($port)
     {
         if (is_null($port) || (is_integer($port) && ($port >= 1 && $port <= 65535))) {
@@ -536,6 +551,7 @@ protected function filterPort($port)
      *
      * @return string The URI path.
      */
+    #[\ReturnTypeWillChange]
     public function getPath()
     {
         return $this->path;
@@ -564,6 +580,7 @@ public function getPath()
      *
      * @throws InvalidArgumentException For invalid paths.
      */
+    #[\ReturnTypeWillChange]
     public function withPath($path)
     {
         if (!is_string($path)) {
@@ -591,6 +608,7 @@ public function withPath($path)
      *
      * @return string The base path segment of the URI.
      */
+    #[\ReturnTypeWillChange]
     public function getBasePath()
     {
         return $this->basePath;
@@ -605,6 +623,7 @@ public function getBasePath()
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function withBasePath($basePath)
     {
         if (!is_string($basePath)) {
@@ -638,6 +657,7 @@ public function withBasePath($basePath)
      *
      * @link   http://www.faqs.org/rfcs/rfc3986.html
      */
+    #[\ReturnTypeWillChange]
     protected function filterPath($path)
     {
         return preg_replace_callback(
@@ -670,6 +690,7 @@ function ($match) {
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getQuery()
     {
         return $this->query;
@@ -692,6 +713,7 @@ public function getQuery()
      *
      * @throws InvalidArgumentException For invalid query strings.
      */
+    #[\ReturnTypeWillChange]
     public function withQuery($query)
     {
         if (!is_string($query) && (!is_object($query) || !method_exists($query, '__toString'))) {
@@ -711,6 +733,7 @@ public function withQuery($query)
      *
      * @return string The percent-encoded query string.
      */
+    #[\ReturnTypeWillChange]
     protected function filterQuery($query)
     {
         return preg_replace_callback(
@@ -739,6 +762,7 @@ function ($match) {
      *
      * @return string The URI fragment.
      */
+    #[\ReturnTypeWillChange]
     public function getFragment()
     {
         return $this->fragment;
@@ -759,6 +783,7 @@ public function getFragment()
      *
      * @return static A new instance with the specified fragment.
      */
+    #[\ReturnTypeWillChange]
     public function withFragment($fragment)
     {
         if (!is_string($fragment) && (!is_object($fragment) || !method_exists($fragment, '__toString'))) {
@@ -822,6 +847,7 @@ public function __toString()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getBaseUrl()
     {
         $scheme = $this->getScheme();
diff --git a/Slim/Interfaces/CallableResolverInterface.php b/Slim/Interfaces/CallableResolverInterface.php
index b3fd3fa9..7fae7c5d 100644
--- a/Slim/Interfaces/CallableResolverInterface.php
+++ b/Slim/Interfaces/CallableResolverInterface.php
@@ -20,5 +20,6 @@ interface CallableResolverInterface
      *
      * @throws RuntimeException
      */
+    #[\ReturnTypeWillChange]
     public function resolve($toResolve);
 }
diff --git a/Slim/Interfaces/CollectionInterface.php b/Slim/Interfaces/CollectionInterface.php
index 9af58902..d77d5c22 100644
--- a/Slim/Interfaces/CollectionInterface.php
+++ b/Slim/Interfaces/CollectionInterface.php
@@ -29,6 +29,7 @@ public function set($key, $value);
      *
      * @return mixed The key's value, or the default value
      */
+    #[\ReturnTypeWillChange]
     public function get($key, $default = null);
 
     /**
@@ -36,6 +37,7 @@ public function get($key, $default = null);
      *
      * @param array $items Key-value array of data to append to this collection
      */
+    #[\ReturnTypeWillChange]
     public function replace(array $items);
 
     /**
@@ -43,6 +45,7 @@ public function replace(array $items);
      *
      * @return array The collection's source data
      */
+    #[\ReturnTypeWillChange]
     public function all();
 
     /**
@@ -52,6 +55,7 @@ public function all();
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function has($key);
 
     /**
@@ -59,6 +63,7 @@ public function has($key);
      *
      * @param string $key The data key
      */
+    #[\ReturnTypeWillChange]
     public function remove($key);
 
     /**
diff --git a/Slim/Interfaces/Http/CookiesInterface.php b/Slim/Interfaces/Http/CookiesInterface.php
index a1673a18..aa293013 100644
--- a/Slim/Interfaces/Http/CookiesInterface.php
+++ b/Slim/Interfaces/Http/CookiesInterface.php
@@ -19,6 +19,7 @@ interface CookiesInterface
      *
      * @return mixed Cookie value if present, else default
      */
+    #[\ReturnTypeWillChange]
     public function get($name, $default = null);
 
     /**
@@ -27,6 +28,7 @@ public function get($name, $default = null);
      * @param string       $name  Cookie name
      * @param string|array $value Cookie value, or cookie properties
      */
+    #[\ReturnTypeWillChange]
     public function set($name, $value);
 
     /**
@@ -34,6 +36,7 @@ public function set($name, $value);
      *
      * @return string[]
      */
+    #[\ReturnTypeWillChange]
     public function toHeaders();
 
     /**
@@ -45,5 +48,6 @@ public function toHeaders();
      *
      * @throws InvalidArgumentException if the cookie data cannot be parsed
      */
+    #[\ReturnTypeWillChange]
     public static function parseHeader($header);
 }
diff --git a/Slim/Interfaces/Http/EnvironmentInterface.php b/Slim/Interfaces/Http/EnvironmentInterface.php
index 49eae5b6..aa39a194 100644
--- a/Slim/Interfaces/Http/EnvironmentInterface.php
+++ b/Slim/Interfaces/Http/EnvironmentInterface.php
@@ -16,5 +16,6 @@ interface EnvironmentInterface
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public static function mock(array $settings = []);
 }
diff --git a/Slim/Interfaces/Http/HeadersInterface.php b/Slim/Interfaces/Http/HeadersInterface.php
index f86cab5e..2fab0e7d 100644
--- a/Slim/Interfaces/Http/HeadersInterface.php
+++ b/Slim/Interfaces/Http/HeadersInterface.php
@@ -34,5 +34,6 @@ public function add($key, $value);
      *
      * @return string Normalized header name
      */
+    #[\ReturnTypeWillChange]
     public function normalizeKey($key);
 }
diff --git a/Slim/Interfaces/InvocationStrategyInterface.php b/Slim/Interfaces/InvocationStrategyInterface.php
index 0e73a42d..16e7424e 100644
--- a/Slim/Interfaces/InvocationStrategyInterface.php
+++ b/Slim/Interfaces/InvocationStrategyInterface.php
@@ -20,6 +20,7 @@ interface InvocationStrategyInterface
      *
      * @return ResponseInterface|string
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(
         callable $callable,
         ServerRequestInterface $request,
diff --git a/Slim/Interfaces/RouteGroupInterface.php b/Slim/Interfaces/RouteGroupInterface.php
index 31340b13..876e4e70 100644
--- a/Slim/Interfaces/RouteGroupInterface.php
+++ b/Slim/Interfaces/RouteGroupInterface.php
@@ -16,6 +16,7 @@ interface RouteGroupInterface
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getPattern();
 
     /**
@@ -25,6 +26,7 @@ public function getPattern();
      *
      * @return RouteGroupInterface
      */
+    #[\ReturnTypeWillChange]
     public function add($callable);
 
     /**
diff --git a/Slim/Interfaces/RouteInterface.php b/Slim/Interfaces/RouteInterface.php
index 8d0f4f05..caae2ea6 100644
--- a/Slim/Interfaces/RouteInterface.php
+++ b/Slim/Interfaces/RouteInterface.php
@@ -21,6 +21,7 @@ interface RouteInterface
      *
      * @return string|null
      */
+    #[\ReturnTypeWillChange]
     public function getArgument($name, $default = null);
 
     /**
@@ -28,6 +29,7 @@ public function getArgument($name, $default = null);
      *
      * @return string[]
      */
+    #[\ReturnTypeWillChange]
     public function getArguments();
 
     /**
@@ -35,6 +37,7 @@ public function getArguments();
      *
      * @return null|string
      */
+    #[\ReturnTypeWillChange]
     public function getName();
 
     /**
@@ -42,6 +45,7 @@ public function getName();
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getPattern();
 
     /**
@@ -52,6 +56,7 @@ public function getPattern();
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function setArgument($name, $value);
 
     /**
@@ -61,6 +66,7 @@ public function setArgument($name, $value);
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function setArguments(array $arguments);
 
     /**
@@ -72,6 +78,7 @@ public function setArguments(array $arguments);
      *
      * @throws InvalidArgumentException If an unknown buffering mode is specified
      */
+    #[\ReturnTypeWillChange]
     public function setOutputBuffering($mode);
 
     /**
@@ -83,6 +90,7 @@ public function setOutputBuffering($mode);
      *
      * @throws InvalidArgumentException if the route name is not a string
      */
+    #[\ReturnTypeWillChange]
     public function setName($name);
 
     /**
@@ -94,6 +102,7 @@ public function setName($name);
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function add($callable);
 
     /**
@@ -102,6 +111,7 @@ public function add($callable);
      * @param ServerRequestInterface $request
      * @param array                  $arguments
      */
+    #[\ReturnTypeWillChange]
     public function prepare(ServerRequestInterface $request, array $arguments);
 
     /**
@@ -116,6 +126,7 @@ public function prepare(ServerRequestInterface $request, array $arguments);
      *
      * @return ResponseInterface
      */
+    #[\ReturnTypeWillChange]
     public function run(ServerRequestInterface $request, ResponseInterface $response);
 
     /**
@@ -130,5 +141,6 @@ public function run(ServerRequestInterface $request, ResponseInterface $response
      *
      * @return ResponseInterface
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(ServerRequestInterface $request, ResponseInterface $response);
 }
diff --git a/Slim/Interfaces/RouterInterface.php b/Slim/Interfaces/RouterInterface.php
index 767699a6..612a2b44 100644
--- a/Slim/Interfaces/RouterInterface.php
+++ b/Slim/Interfaces/RouterInterface.php
@@ -28,6 +28,7 @@ interface RouterInterface
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function map($methods, $pattern, $handler);
 
     /**
@@ -39,6 +40,7 @@ public function map($methods, $pattern, $handler);
      *
      * @link   https://github.com/nikic/FastRoute/blob/master/src/Dispatcher.php
      */
+    #[\ReturnTypeWillChange]
     public function dispatch(ServerRequestInterface $request);
 
     /**
@@ -49,6 +51,7 @@ public function dispatch(ServerRequestInterface $request);
      *
      * @return RouteGroupInterface
      */
+    #[\ReturnTypeWillChange]
     public function pushGroup($pattern, $callable);
 
     /**
@@ -56,6 +59,7 @@ public function pushGroup($pattern, $callable);
      *
      * @return bool True if successful, else False
      */
+    #[\ReturnTypeWillChange]
     public function popGroup();
 
     /**
@@ -67,6 +71,7 @@ public function popGroup();
      *
      * @throws RuntimeException   If named route does not exist
      */
+    #[\ReturnTypeWillChange]
     public function getNamedRoute($name);
 
     /**
@@ -74,6 +79,7 @@ public function getNamedRoute($name);
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     public function lookupRoute($identifier);
 
     /**
@@ -88,6 +94,7 @@ public function lookupRoute($identifier);
      * @throws RuntimeException         If named route does not exist
      * @throws InvalidArgumentException If required data not provided
      */
+    #[\ReturnTypeWillChange]
     public function relativePathFor($name, array $data = [], array $queryParams = []);
 
     /**
@@ -102,5 +109,6 @@ public function relativePathFor($name, array $data = [], array $queryParams = []
      * @throws RuntimeException         If named route does not exist
      * @throws InvalidArgumentException If required data not provided
      */
+    #[\ReturnTypeWillChange]
     public function pathFor($name, array $data = [], array $queryParams = []);
 }
diff --git a/Slim/MiddlewareAwareTrait.php b/Slim/MiddlewareAwareTrait.php
index 3f323661..d124bb14 100644
--- a/Slim/MiddlewareAwareTrait.php
+++ b/Slim/MiddlewareAwareTrait.php
@@ -50,6 +50,7 @@ trait MiddlewareAwareTrait
      * @throws RuntimeException         If middleware is added while the stack is dequeuing
      * @throws UnexpectedValueException If the middleware doesn't return a Psr\Http\Message\ResponseInterface
      */
+    #[\ReturnTypeWillChange]
     protected function addMiddleware(callable $callable)
     {
         if ($this->middlewareLock) {
@@ -87,6 +88,7 @@ protected function addMiddleware(callable $callable)
      *
      * @throws RuntimeException if the stack is seeded more than once
      */
+    #[\ReturnTypeWillChange]
     protected function seedMiddlewareStack(callable $kernel = null)
     {
         if (!is_null($this->tip)) {
@@ -106,6 +108,7 @@ protected function seedMiddlewareStack(callable $kernel = null)
      *
      * @return ResponseInterface
      */
+    #[\ReturnTypeWillChange]
     public function callMiddlewareStack(ServerRequestInterface $request, ResponseInterface $response)
     {
         if (is_null($this->tip)) {
diff --git a/Slim/Routable.php b/Slim/Routable.php
index 2563e053..86f8a476 100644
--- a/Slim/Routable.php
+++ b/Slim/Routable.php
@@ -56,6 +56,7 @@ public function __construct($pattern, $callable)
      *
      * @return callable[]
      */
+    #[\ReturnTypeWillChange]
     public function getMiddleware()
     {
         return $this->middleware;
@@ -66,6 +67,7 @@ public function getMiddleware()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getPattern()
     {
         return $this->pattern;
@@ -78,6 +80,7 @@ public function getPattern()
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function setContainer(ContainerInterface $container)
     {
         $this->container = $container;
@@ -91,6 +94,7 @@ public function setContainer(ContainerInterface $container)
      *
      * @return static
      */
+    #[\ReturnTypeWillChange]
     public function add($callable)
     {
         $this->middleware[] = new DeferredCallable($callable, $this->container);
@@ -102,6 +106,7 @@ public function add($callable)
      *
      * @param string $newPattern
      */
+    #[\ReturnTypeWillChange]
     public function setPattern($newPattern)
     {
         $this->pattern = $newPattern;
diff --git a/Slim/Route.php b/Slim/Route.php
index 7af218cc..110a0d6f 100644
--- a/Slim/Route.php
+++ b/Slim/Route.php
@@ -87,6 +87,7 @@ public function __construct($methods, $pattern, $callable, $groups = [], $identi
         $this->identifier = 'route' . $identifier;
     }
 
+    #[\ReturnTypeWillChange]
     public function finalize()
     {
         if ($this->finalized) {
@@ -112,6 +113,7 @@ public function finalize()
      *
      * @return callable
      */
+    #[\ReturnTypeWillChange]
     public function getCallable()
     {
         return $this->callable;
@@ -122,6 +124,7 @@ public function getCallable()
      *
      * @param string|Closure $callable
      */
+    #[\ReturnTypeWillChange]
     public function setCallable($callable)
     {
         $this->callable = $callable;
@@ -132,6 +135,7 @@ public function setCallable($callable)
      *
      * @return string[]
      */
+    #[\ReturnTypeWillChange]
     public function getMethods()
     {
         return $this->methods;
@@ -142,6 +146,7 @@ public function getMethods()
      *
      * @return RouteGroup[]
      */
+    #[\ReturnTypeWillChange]
     public function getGroups()
     {
         return $this->groups;
@@ -150,6 +155,7 @@ public function getGroups()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function getName()
     {
         return $this->name;
@@ -160,6 +166,7 @@ public function getName()
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getIdentifier()
     {
         return $this->identifier;
@@ -170,6 +177,7 @@ public function getIdentifier()
      *
      * @return boolean|string
      */
+    #[\ReturnTypeWillChange]
     public function getOutputBuffering()
     {
         return $this->outputBuffering;
@@ -178,6 +186,7 @@ public function getOutputBuffering()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function setOutputBuffering($mode)
     {
         if (!in_array($mode, [false, 'prepend', 'append'], true)) {
@@ -190,6 +199,7 @@ public function setOutputBuffering($mode)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function setName($name)
     {
         if (!is_string($name)) {
@@ -202,6 +212,7 @@ public function setName($name)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function setArgument($name, $value, $includeInSavedArguments = true)
     {
         if ($includeInSavedArguments) {
@@ -214,6 +225,7 @@ public function setArgument($name, $value, $includeInSavedArguments = true)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function setArguments(array $arguments, $includeInSavedArguments = true)
     {
         if ($includeInSavedArguments) {
@@ -226,6 +238,7 @@ public function setArguments(array $arguments, $includeInSavedArguments = true)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function getArguments()
     {
         return $this->arguments;
@@ -245,6 +258,7 @@ public function getArgument($name, $default = null)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function prepare(ServerRequestInterface $request, array $arguments)
     {
         // Remove temp arguments
@@ -259,6 +273,7 @@ public function prepare(ServerRequestInterface $request, array $arguments)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function run(ServerRequestInterface $request, ResponseInterface $response)
     {
         // Finalise route now that we are about to run it
@@ -271,6 +286,7 @@ public function run(ServerRequestInterface $request, ResponseInterface $response
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(ServerRequestInterface $request, ResponseInterface $response)
     {
         $this->callable = $this->resolveCallable($this->callable);
diff --git a/Slim/RouteGroup.php b/Slim/RouteGroup.php
index 26fe5c07..b440b499 100644
--- a/Slim/RouteGroup.php
+++ b/Slim/RouteGroup.php
@@ -15,6 +15,7 @@ class RouteGroup extends Routable implements RouteGroupInterface
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function __invoke(App $app = null)
     {
         $callable = $this->resolveCallable($this->callable);
diff --git a/Slim/Router.php b/Slim/Router.php
index 08a95018..dfb68eed 100644
--- a/Slim/Router.php
+++ b/Slim/Router.php
@@ -96,6 +96,7 @@ public function __construct(RouteParser $parser = null)
      * @return static
      * @throws InvalidArgumentException
      */
+    #[\ReturnTypeWillChange]
     public function setBasePath($basePath)
     {
         if (!is_string($basePath)) {
@@ -112,6 +113,7 @@ public function setBasePath($basePath)
      *
      * @return string
      */
+    #[\ReturnTypeWillChange]
     public function getBasePath()
     {
         return $this->basePath;
@@ -127,6 +129,7 @@ public function getBasePath()
      * @throws InvalidArgumentException If cacheFile is not a string or not false
      * @throws RuntimeException         If cacheFile directory is not writable
      */
+    #[\ReturnTypeWillChange]
     public function setCacheFile($cacheFile)
     {
         if (!is_string($cacheFile) && $cacheFile !== false) {
@@ -152,6 +155,7 @@ public function setCacheFile($cacheFile)
     /**
      * @param ContainerInterface $container
      */
+    #[\ReturnTypeWillChange]
     public function setContainer(ContainerInterface $container)
     {
         $this->container = $container;
@@ -160,6 +164,7 @@ public function setContainer(ContainerInterface $container)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function map($methods, $pattern, $handler)
     {
         if (!is_string($pattern)) {
@@ -186,6 +191,7 @@ public function map($methods, $pattern, $handler)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function dispatch(ServerRequestInterface $request)
     {
         $uri = '/' . ltrim($request->getUri()->getPath(), '/');
@@ -205,6 +211,7 @@ public function dispatch(ServerRequestInterface $request)
      *
      * @return RouteInterface
      */
+    #[\ReturnTypeWillChange]
     protected function createRoute($methods, $pattern, $callable)
     {
         $route = new Route($methods, $pattern, $callable, $this->routeGroups, $this->routeCounter);
@@ -218,6 +225,7 @@ protected function createRoute($methods, $pattern, $callable)
     /**
      * @return Dispatcher
      */
+    #[\ReturnTypeWillChange]
     protected function createDispatcher()
     {
         if ($this->dispatcher) {
@@ -247,6 +255,7 @@ protected function createDispatcher()
     /**
      * @param Dispatcher $dispatcher
      */
+    #[\ReturnTypeWillChange]
     public function setDispatcher(Dispatcher $dispatcher)
     {
         $this->dispatcher = $dispatcher;
@@ -257,6 +266,7 @@ public function setDispatcher(Dispatcher $dispatcher)
      *
      * @return Route[]
      */
+    #[\ReturnTypeWillChange]
     public function getRoutes()
     {
         return $this->routes;
@@ -265,6 +275,7 @@ public function getRoutes()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function getNamedRoute($name)
     {
         foreach ($this->routes as $route) {
@@ -282,6 +293,7 @@ public function getNamedRoute($name)
      *
      * @throws RuntimeException   If named route does not exist
      */
+    #[\ReturnTypeWillChange]
     public function removeNamedRoute($name)
     {
         $route = $this->getNamedRoute($name);
@@ -295,6 +307,7 @@ public function removeNamedRoute($name)
      *
      * @return string A group pattern to prefix routes with
      */
+    #[\ReturnTypeWillChange]
     protected function processGroups()
     {
         $pattern = "";
@@ -307,6 +320,7 @@ protected function processGroups()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function pushGroup($pattern, $callable)
     {
         $group = new RouteGroup($pattern, $callable);
@@ -317,6 +331,7 @@ public function pushGroup($pattern, $callable)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function popGroup()
     {
         $group = array_pop($this->routeGroups);
@@ -326,6 +341,7 @@ public function popGroup()
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function lookupRoute($identifier)
     {
         if (!isset($this->routes[$identifier])) {
@@ -337,6 +353,7 @@ public function lookupRoute($identifier)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function relativePathFor($name, array $data = [], array $queryParams = [])
     {
         $route = $this->getNamedRoute($name);
@@ -396,6 +413,7 @@ public function relativePathFor($name, array $data = [], array $queryParams = []
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function pathFor($name, array $data = [], array $queryParams = [])
     {
         return $this->urlFor($name, $data, $queryParams);
@@ -413,6 +431,7 @@ public function pathFor($name, array $data = [], array $queryParams = [])
      * @throws RuntimeException         If named route does not exist
      * @throws InvalidArgumentException If required data not provided
      */
+    #[\ReturnTypeWillChange]
     public function urlFor($name, array $data = [], array $queryParams = [])
     {
         $url = $this->relativePathFor($name, $data, $queryParams);
@@ -437,6 +456,7 @@ public function urlFor($name, array $data = [], array $queryParams = [])
      * @throws RuntimeException         If named route does not exist
      * @throws InvalidArgumentException If required data not provided
      */
+    #[\ReturnTypeWillChange]
     public function fullUrlFor(UriInterface $uri, $routeName, array $data = [], array $queryParams = [])
     {
         $path = $this->urlFor($routeName, $data, $queryParams);