diff --git a/.github/workflows/intl-data-tests.yml b/.github/workflows/intl-data-tests.yml
new file mode 100644
index 0000000000..17e26dad0d
--- /dev/null
+++ b/.github/workflows/intl-data-tests.yml
@@ -0,0 +1,47 @@
+name: Intl data tests
+
+on:
+    push:
+        paths:
+          - 'src/Symfony/Component/Intl/Resources/data/**'
+    pull_request:
+        paths:
+          - 'src/Symfony/Component/Intl/Resources/data/**'
+
+jobs:
+
+    tests:
+        name: Tests (intl-data)
+        runs-on: ubuntu-latest
+
+        steps:
+            -   name: Checkout
+                uses: actions/checkout@v2
+
+            -   name: Define the ICU version
+                run: |
+                    SYMFONY_ICU_VERSION=$(php -r 'require "src/Symfony/Component/Intl/Intl.php"; echo Symfony\Component\Intl\Intl::getIcuStubVersion();')
+                    echo "SYMFONY_ICU_VERSION=$SYMFONY_ICU_VERSION" >> $GITHUB_ENV
+
+            -   name: Setup PHP
+                uses: shivammathur/setup-php@v2
+                with:
+                    coverage: "none"
+                    extensions: "zip,intl-${{env.SYMFONY_ICU_VERSION}}"
+                    ini-values: "memory_limit=-1"
+                    php-version: "7.4"
+
+            -   name: Install dependencies
+                run: |
+                    echo "::group::composer update"
+                    composer update --no-progress --no-suggest --ansi
+                    echo "::endgroup::"
+                    echo "::group::install phpunit"
+                    ./phpunit install
+                    echo "::endgroup::"
+
+            -   name: Report the ICU version
+                run: icu-config --version && php -i | grep 'ICU version'
+
+            -   name: Run intl-data tests
+                run: ./phpunit --group intl-data -v
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/RedirectControllerTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/RedirectControllerTest.php
index 732ac3e2d6..f053af3fa4 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/RedirectControllerTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Controller/RedirectControllerTest.php
@@ -302,16 +302,19 @@ class RedirectControllerTest extends TestCase
         $baseUrl = '/base';
         $port = 80;
 
-        $request = $this->createRequestObject($scheme, $host, $port, $baseUrl, 'b.se=zaza');
+        $request = $this->createRequestObject($scheme, $host, $port, $baseUrl, 'b.se=zaza&f[%2525][%26][%3D][p.c]=d');
         $request->attributes = new ParameterBag(['_route_params' => ['base2' => 'zaza']]);
         $urlGenerator = $this->getMockBuilder(UrlGeneratorInterface::class)->getMock();
-        $urlGenerator->expects($this->exactly(2))->method('generate')->willReturn('/test?b.se=zaza&base2=zaza')->with('/test', ['b.se' => 'zaza', 'base2' => 'zaza'], UrlGeneratorInterface::ABSOLUTE_URL);
+        $urlGenerator->expects($this->exactly(2))
+             ->method('generate')
+             ->willReturn('/test?b.se=zaza&base2=zaza&f[%2525][%26][%3D][p.c]=d')
+             ->with('/test', ['b.se' => 'zaza', 'base2' => 'zaza', 'f' => ['%25' => ['&' => ['=' => ['p.c' => 'd']]]]], UrlGeneratorInterface::ABSOLUTE_URL);
 
         $controller = new RedirectController($urlGenerator);
-        $this->assertRedirectUrl($controller->redirectAction($request, '/test', false, false, false, true), '/test?b.se=zaza&base2=zaza');
+        $this->assertRedirectUrl($controller->redirectAction($request, '/test', false, false, false, true), '/test?b.se=zaza&base2=zaza&f[%2525][%26][%3D][p.c]=d');
 
         $request->attributes->set('_route_params', ['base2' => 'zaza', 'route' => '/test', 'ignoreAttributes' => false, 'keepRequestMethod' => false, 'keepQueryParams' => true]);
-        $this->assertRedirectUrl($controller($request), '/test?b.se=zaza&base2=zaza');
+        $this->assertRedirectUrl($controller($request), '/test?b.se=zaza&base2=zaza&f[%2525][%26][%3D][p.c]=d');
     }
 
     public function testRedirectWithQueryWithRouteParamsOveriding()
diff --git a/src/Symfony/Component/Serializer/Normalizer/DenormalizerInterface.php b/src/Symfony/Component/Serializer/Normalizer/DenormalizerInterface.php
index 337fe2e8c2..d903b3912d 100644
--- a/src/Symfony/Component/Serializer/Normalizer/DenormalizerInterface.php
+++ b/src/Symfony/Component/Serializer/Normalizer/DenormalizerInterface.php
@@ -32,7 +32,7 @@ interface DenormalizerInterface
      * @param string $format  Format the given data was extracted from
      * @param array  $context Options available to the denormalizer
      *
-     * @return object|array
+     * @return mixed
      *
      * @throws BadMethodCallException   Occurs when the normalizer is not called in an expected context
      * @throws InvalidArgumentException Occurs when the arguments are not coherent or not supported
diff --git a/src/Symfony/Component/Serializer/SerializerInterface.php b/src/Symfony/Component/Serializer/SerializerInterface.php
index f67dd66edd..96e144e90e 100644
--- a/src/Symfony/Component/Serializer/SerializerInterface.php
+++ b/src/Symfony/Component/Serializer/SerializerInterface.php
@@ -32,7 +32,7 @@ interface SerializerInterface
      *
      * @param mixed $data
      *
-     * @return object|array
+     * @return mixed
      */
     public function deserialize($data, string $type, string $format, array $context = []);
 }