diff --git a/UPGRADE-4.0.md b/UPGRADE-4.0.md
index 23ed6fbd33..8947744a9f 100644
--- a/UPGRADE-4.0.md
+++ b/UPGRADE-4.0.md
@@ -230,7 +230,7 @@ DependencyInjection
    supported.
 
  * The ``strict`` attribute in service arguments has been removed.
-   The attribute is ignored since 3.0, so you can simply remove it.
+   The attribute is ignored since 3.0, you can remove it.
 
  * Top-level anonymous services in XML are no longer supported.
 
diff --git a/src/Symfony/Bridge/Doctrine/DependencyInjection/CompilerPass/RegisterMappingsPass.php b/src/Symfony/Bridge/Doctrine/DependencyInjection/CompilerPass/RegisterMappingsPass.php
index 5c33f71f04..5b1d78fbf8 100644
--- a/src/Symfony/Bridge/Doctrine/DependencyInjection/CompilerPass/RegisterMappingsPass.php
+++ b/src/Symfony/Bridge/Doctrine/DependencyInjection/CompilerPass/RegisterMappingsPass.php
@@ -24,8 +24,8 @@ use Symfony\Component\DependencyInjection\Reference;
  * The compiler pass is meant to register the mappings with the metadata
  * chain driver corresponding to one of the object managers.
  *
- * For concrete implementations that are easy to use, see the
- * RegisterXyMappingsPass classes in the DoctrineBundle resp.
+ * For concrete implementations, see the RegisterXyMappingsPass classes
+ * in the DoctrineBundle resp.
  * DoctrineMongodbBundle, DoctrineCouchdbBundle and DoctrinePhpcrBundle.
  *
  * @author David Buchmann <david@liip.ch>
diff --git a/src/Symfony/Bridge/Doctrine/Form/DoctrineOrmTypeGuesser.php b/src/Symfony/Bridge/Doctrine/Form/DoctrineOrmTypeGuesser.php
index d9f7f391d2..49dfd9bfbc 100644
--- a/src/Symfony/Bridge/Doctrine/Form/DoctrineOrmTypeGuesser.php
+++ b/src/Symfony/Bridge/Doctrine/Form/DoctrineOrmTypeGuesser.php
@@ -165,7 +165,7 @@ class DoctrineOrmTypeGuesser implements FormTypeGuesserInterface
         // normalize class name
         $class = self::getRealClass(ltrim($class, '\\'));
 
-        if (array_key_exists($class, $this->cache)) {
+        if (\array_key_exists($class, $this->cache)) {
             return $this->cache[$class];
         }
 
diff --git a/src/Symfony/Bridge/Doctrine/Security/User/EntityUserProvider.php b/src/Symfony/Bridge/Doctrine/Security/User/EntityUserProvider.php
index 769e9bb20e..20f6839957 100644
--- a/src/Symfony/Bridge/Doctrine/Security/User/EntityUserProvider.php
+++ b/src/Symfony/Bridge/Doctrine/Security/User/EntityUserProvider.php
@@ -20,7 +20,7 @@ use Symfony\Component\Security\Core\User\UserProviderInterface;
 /**
  * Wrapper around a Doctrine ObjectManager.
  *
- * Provides easy to use provisioning for Doctrine entity users.
+ * Provides provisioning for Doctrine entity users.
  *
  * @author Fabien Potencier <fabien@symfony.com>
  * @author Johannes M. Schmitt <schmittjoh@gmail.com>
diff --git a/src/Symfony/Bridge/Monolog/Handler/FingersCrossed/HttpCodeActivationStrategy.php b/src/Symfony/Bridge/Monolog/Handler/FingersCrossed/HttpCodeActivationStrategy.php
index b31817d76d..ae8fd3650a 100644
--- a/src/Symfony/Bridge/Monolog/Handler/FingersCrossed/HttpCodeActivationStrategy.php
+++ b/src/Symfony/Bridge/Monolog/Handler/FingersCrossed/HttpCodeActivationStrategy.php
@@ -31,10 +31,10 @@ class HttpCodeActivationStrategy extends ErrorLevelActivationStrategy
     public function __construct(RequestStack $requestStack, array $exclusions, $actionLevel)
     {
         foreach ($exclusions as $exclusion) {
-            if (!array_key_exists('code', $exclusion)) {
+            if (!\array_key_exists('code', $exclusion)) {
                 throw new \LogicException(sprintf('An exclusion must have a "code" key'));
             }
-            if (!array_key_exists('urls', $exclusion)) {
+            if (!\array_key_exists('urls', $exclusion)) {
                 throw new \LogicException(sprintf('An exclusion must have a "urls" key'));
             }
         }
diff --git a/src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/Fixtures/proxy-factory.php b/src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/Fixtures/proxy-factory.php
index af3b972cdf..e571b85571 100644
--- a/src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/Fixtures/proxy-factory.php
+++ b/src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/Fixtures/proxy-factory.php
@@ -1,7 +1,6 @@
 <?php
 
-return new class
-{
+return new class() {
     public $proxyClass;
     private $privates = [];
 
diff --git a/src/Symfony/Bridge/Twig/NodeVisitor/Scope.php b/src/Symfony/Bridge/Twig/NodeVisitor/Scope.php
index d5bcfa8b8f..642623f2a6 100644
--- a/src/Symfony/Bridge/Twig/NodeVisitor/Scope.php
+++ b/src/Symfony/Bridge/Twig/NodeVisitor/Scope.php
@@ -77,7 +77,7 @@ class Scope
      */
     public function has($key)
     {
-        if (array_key_exists($key, $this->data)) {
+        if (\array_key_exists($key, $this->data)) {
             return true;
         }
 
@@ -98,7 +98,7 @@ class Scope
      */
     public function get($key, $default = null)
     {
-        if (array_key_exists($key, $this->data)) {
+        if (\array_key_exists($key, $this->data)) {
             return $this->data[$key];
         }
 
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
index a4a10805f6..7d3373f3eb 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
@@ -138,7 +138,7 @@ EOF
         $steps = explode('.', $path);
 
         foreach ($steps as $step) {
-            if (!array_key_exists($step, $config)) {
+            if (!\array_key_exists($step, $config)) {
                 throw new LogicException(sprintf('Unable to find configuration for "%s.%s"', $alias, $path));
             }
 
diff --git a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/Descriptor.php b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/Descriptor.php
index d2afe921ff..484ca4fefd 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/Descriptor.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/Descriptor.php
@@ -11,6 +11,7 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Console\Descriptor;
 
+use Symfony\Component\Config\Resource\ClassExistenceResource;
 use Symfony\Component\Console\Descriptor\DescriptorInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\DependencyInjection\Alias;
@@ -226,7 +227,7 @@ abstract class Descriptor implements DescriptorInterface
             return $builder->getDefinition($serviceId);
         }
 
-        // Some service IDs don't have a Definition, they're simply an Alias
+        // Some service IDs don't have a Definition, they're aliases
         if ($builder->hasAlias($serviceId)) {
             return $builder->getAlias($serviceId);
         }
@@ -292,6 +293,11 @@ abstract class Descriptor implements DescriptorInterface
     {
         $resolvedClass = $class;
         try {
+            $resource = new ClassExistenceResource($class, false);
+
+            // isFresh() will explode ONLY if a parent class/trait does not exist
+            $resource->isFresh(0);
+
             $r = new \ReflectionClass($class);
             $resolvedClass = $r->name;
 
diff --git a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/JsonDescriptor.php b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/JsonDescriptor.php
index 06d57dcdb2..44fae86bc0 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/JsonDescriptor.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/JsonDescriptor.php
@@ -156,7 +156,7 @@ class JsonDescriptor extends Descriptor
      */
     protected function describeEventDispatcherListeners(EventDispatcherInterface $eventDispatcher, array $options = [])
     {
-        $this->writeData($this->getEventDispatcherListenersData($eventDispatcher, array_key_exists('event', $options) ? $options['event'] : null), $options);
+        $this->writeData($this->getEventDispatcherListenersData($eventDispatcher, \array_key_exists('event', $options) ? $options['event'] : null), $options);
     }
 
     /**
diff --git a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/MarkdownDescriptor.php b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/MarkdownDescriptor.php
index 89180c03ca..56e11b07f6 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/MarkdownDescriptor.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/MarkdownDescriptor.php
@@ -274,7 +274,7 @@ class MarkdownDescriptor extends Descriptor
      */
     protected function describeEventDispatcherListeners(EventDispatcherInterface $eventDispatcher, array $options = [])
     {
-        $event = array_key_exists('event', $options) ? $options['event'] : null;
+        $event = \array_key_exists('event', $options) ? $options['event'] : null;
 
         $title = 'Registered listeners';
         if (null !== $event) {
diff --git a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/TextDescriptor.php b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/TextDescriptor.php
index 79566a1ad9..c0ec5e412e 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/TextDescriptor.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/TextDescriptor.php
@@ -385,7 +385,7 @@ class TextDescriptor extends Descriptor
      */
     protected function describeEventDispatcherListeners(EventDispatcherInterface $eventDispatcher, array $options = [])
     {
-        $event = array_key_exists('event', $options) ? $options['event'] : null;
+        $event = \array_key_exists('event', $options) ? $options['event'] : null;
 
         if (null !== $event) {
             $title = sprintf('Registered Listeners for "%s" Event', $event);
diff --git a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/XmlDescriptor.php b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/XmlDescriptor.php
index d66a081aab..3e66b05d0b 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/XmlDescriptor.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Console/Descriptor/XmlDescriptor.php
@@ -112,7 +112,7 @@ class XmlDescriptor extends Descriptor
      */
     protected function describeEventDispatcherListeners(EventDispatcherInterface $eventDispatcher, array $options = [])
     {
-        $this->writeDocument($this->getEventDispatcherListenersDocument($eventDispatcher, array_key_exists('event', $options) ? $options['event'] : null));
+        $this->writeDocument($this->getEventDispatcherListenersDocument($eventDispatcher, \array_key_exists('event', $options) ? $options['event'] : null));
     }
 
     /**
diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
index 53a3220000..0d2aa264ad 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
@@ -327,7 +327,7 @@ class Configuration implements ConfigurationInterface
                                                 }
 
                                                 foreach ($places as $name => $place) {
-                                                    if (\is_array($place) && array_key_exists('name', $place)) {
+                                                    if (\is_array($place) && \array_key_exists('name', $place)) {
                                                         continue;
                                                     }
                                                     $place['name'] = $name;
@@ -365,7 +365,7 @@ class Configuration implements ConfigurationInterface
                                                 }
 
                                                 foreach ($transitions as $name => $transition) {
-                                                    if (\is_array($transition) && array_key_exists('name', $transition)) {
+                                                    if (\is_array($transition) && \array_key_exists('name', $transition)) {
                                                         continue;
                                                     }
                                                     $transition['name'] = $name;
diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
index ee23ac58aa..714d92379d 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php
@@ -939,7 +939,7 @@ class FrameworkExtension extends Extension
         foreach ($config['packages'] as $name => $package) {
             if (null !== $package['version_strategy']) {
                 $version = new Reference($package['version_strategy']);
-            } elseif (!array_key_exists('version', $package) && null === $package['json_manifest_path']) {
+            } elseif (!\array_key_exists('version', $package) && null === $package['json_manifest_path']) {
                 // if neither version nor json_manifest_path are specified, use the default
                 $version = $defaultVersion;
             } else {
@@ -1146,7 +1146,7 @@ class FrameworkExtension extends Extension
         $definition = $container->findDefinition('validator.email');
         $definition->replaceArgument(0, $config['email_validation_mode']);
 
-        if (array_key_exists('enable_annotations', $config) && $config['enable_annotations']) {
+        if (\array_key_exists('enable_annotations', $config) && $config['enable_annotations']) {
             if (!$this->annotationsConfigEnabled) {
                 throw new \LogicException('"enable_annotations" on the validator cannot be set as Annotations support is disabled.');
             }
@@ -1154,7 +1154,7 @@ class FrameworkExtension extends Extension
             $validatorBuilder->addMethodCall('enableAnnotationMapping', [new Reference('annotation_reader')]);
         }
 
-        if (array_key_exists('static_method', $config) && $config['static_method']) {
+        if (\array_key_exists('static_method', $config) && $config['static_method']) {
             foreach ($config['static_method'] as $methodName) {
                 $validatorBuilder->addMethodCall('addMethodMapping', [$methodName]);
             }
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Command/CacheClearCommand/CacheClearCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Command/CacheClearCommand/CacheClearCommandTest.php
index e91ecc50ca..9e4c46d585 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Command/CacheClearCommand/CacheClearCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Command/CacheClearCommand/CacheClearCommandTest.php
@@ -51,7 +51,7 @@ class CacheClearCommandTest extends TestCase
         // Ensure that all *.meta files are fresh
         $finder = new Finder();
         $metaFiles = $finder->files()->in($this->kernel->getCacheDir())->name('*.php.meta');
-        // simply check that cache is warmed up
+        // check that cache is warmed up
         $this->assertNotEmpty($metaFiles);
         $configCacheFactory = new ConfigCacheFactory(true);
 
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ContainerDebugCommandTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ContainerDebugCommandTest.php
index 93028bf8c2..ee13386a4b 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ContainerDebugCommandTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/ContainerDebugCommandTest.php
@@ -22,7 +22,7 @@ class ContainerDebugCommandTest extends WebTestCase
 {
     public function testDumpContainerIfNotExists()
     {
-        static::bootKernel(['test_case' => 'ContainerDebug', 'root_config' => 'config.yml']);
+        static::bootKernel(['test_case' => 'ContainerDebug', 'root_config' => 'config.yml', 'debug' => true]);
 
         $application = new Application(static::$kernel);
         $application->setAutoExit(false);
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/WebTestCase.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/WebTestCase.php
index 3f7bb4c7ee..00eda65709 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/WebTestCase.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/WebTestCase.php
@@ -62,7 +62,7 @@ class WebTestCase extends BaseWebTestCase
             $options['test_case'],
             isset($options['root_config']) ? $options['root_config'] : 'config.yml',
             isset($options['environment']) ? $options['environment'] : strtolower(static::getVarDir().$options['test_case']),
-            isset($options['debug']) ? $options['debug'] : true
+            isset($options['debug']) ? $options['debug'] : false
         );
     }
 
diff --git a/src/Symfony/Bundle/SecurityBundle/DependencyInjection/SecurityExtension.php b/src/Symfony/Bundle/SecurityBundle/DependencyInjection/SecurityExtension.php
index 108afc2f7c..a3d41a70a6 100644
--- a/src/Symfony/Bundle/SecurityBundle/DependencyInjection/SecurityExtension.php
+++ b/src/Symfony/Bundle/SecurityBundle/DependencyInjection/SecurityExtension.php
@@ -67,7 +67,7 @@ class SecurityExtension extends Extension implements PrependExtensionInterface
         foreach ($container->getExtensionConfig('framework') as $config) {
             if (isset($config['session']) && \is_array($config['session'])) {
                 $rememberMeSecureDefault = $config['session']['cookie_secure'] ?? $rememberMeSecureDefault;
-                $rememberMeSameSiteDefault = array_key_exists('cookie_samesite', $config['session']) ? $config['session']['cookie_samesite'] : $rememberMeSameSiteDefault;
+                $rememberMeSameSiteDefault = \array_key_exists('cookie_samesite', $config['session']) ? $config['session']['cookie_samesite'] : $rememberMeSameSiteDefault;
             }
         }
         foreach ($this->listenerPositions as $position) {
@@ -412,7 +412,7 @@ class SecurityExtension extends Extension implements PrependExtensionInterface
         foreach ($this->factories as $position) {
             foreach ($position as $factory) {
                 $key = str_replace('-', '_', $factory->getKey());
-                if (array_key_exists($key, $firewall)) {
+                if (\array_key_exists($key, $firewall)) {
                     $listenerKeys[] = $key;
                 }
             }
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/WebTestCase.php b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/WebTestCase.php
index f1d23b6054..9bcbc05324 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/WebTestCase.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/WebTestCase.php
@@ -62,7 +62,7 @@ class WebTestCase extends BaseWebTestCase
             $options['test_case'],
             isset($options['root_config']) ? $options['root_config'] : 'config.yml',
             isset($options['environment']) ? $options['environment'] : strtolower(static::getVarDir().$options['test_case']),
-            isset($options['debug']) ? $options['debug'] : true
+            isset($options['debug']) ? $options['debug'] : false
         );
     }
 
diff --git a/src/Symfony/Bundle/WebServerBundle/Resources/router.php b/src/Symfony/Bundle/WebServerBundle/Resources/router.php
index a366b381aa..30d6b258a2 100644
--- a/src/Symfony/Bundle/WebServerBundle/Resources/router.php
+++ b/src/Symfony/Bundle/WebServerBundle/Resources/router.php
@@ -17,8 +17,8 @@
  * If you have custom directory layout, then you have to write your own router
  * and pass it as a value to 'router' option of server:run command.
  *
- * @author: Michał Pipa <michal.pipa.xsolve@gmail.com>
- * @author: Albert Jessurum <ajessu@gmail.com>
+ * @author Michał Pipa <michal.pipa.xsolve@gmail.com>
+ * @author Albert Jessurum <ajessu@gmail.com>
  */
 
 // Workaround https://bugs.php.net/64566
diff --git a/src/Symfony/Component/BrowserKit/Client.php b/src/Symfony/Component/BrowserKit/Client.php
index 307c3b0252..9678cd381a 100644
--- a/src/Symfony/Component/BrowserKit/Client.php
+++ b/src/Symfony/Component/BrowserKit/Client.php
@@ -548,7 +548,7 @@ abstract class Client
     {
         do {
             $request = $this->history->back();
-        } while (array_key_exists(serialize($request), $this->redirects));
+        } while (\array_key_exists(serialize($request), $this->redirects));
 
         return $this->requestFromRequest($request, false);
     }
@@ -562,7 +562,7 @@ abstract class Client
     {
         do {
             $request = $this->history->forward();
-        } while (array_key_exists(serialize($request), $this->redirects));
+        } while (\array_key_exists(serialize($request), $this->redirects));
 
         return $this->requestFromRequest($request, false);
     }
diff --git a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
index d93ae711bd..6897fbceee 100644
--- a/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
@@ -94,7 +94,7 @@ abstract class AbstractAdapter implements AdapterInterface, CacheInterface, Logg
     }
 
     /**
-     * Returns an ApcuAdapter if supported, a PhpFilesAdapter otherwise.
+     * Returns the best possible adapter that your runtime supports.
      *
      * Using ApcuAdapter makes system caches compatible with read-only filesystems.
      *
@@ -108,16 +108,12 @@ abstract class AbstractAdapter implements AdapterInterface, CacheInterface, Logg
      */
     public static function createSystemCache($namespace, $defaultLifetime, $version, $directory, LoggerInterface $logger = null)
     {
-        if (null === self::$apcuSupported) {
-            self::$apcuSupported = ApcuAdapter::isSupported();
+        $opcache = new PhpFilesAdapter($namespace, $defaultLifetime, $directory, true);
+        if (null !== $logger) {
+            $opcache->setLogger($logger);
         }
 
-        if (!self::$apcuSupported) {
-            $opcache = new PhpFilesAdapter($namespace, $defaultLifetime, $directory, true);
-            if (null !== $logger) {
-                $opcache->setLogger($logger);
-            }
-
+        if (!self::$apcuSupported = self::$apcuSupported ?? ApcuAdapter::isSupported()) {
             return $opcache;
         }
 
@@ -128,7 +124,7 @@ abstract class AbstractAdapter implements AdapterInterface, CacheInterface, Logg
             $apcu->setLogger($logger);
         }
 
-        return $apcu;
+        return new ChainAdapter([$apcu, $opcache]);
     }
 
     public static function createConnection($dsn, array $options = [])
diff --git a/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php b/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
index 8a7d147808..0eceb6e572 100644
--- a/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
+++ b/src/Symfony/Component/Cache/Tests/Adapter/AdapterTestCase.php
@@ -22,7 +22,7 @@ abstract class AdapterTestCase extends CachePoolTest
     {
         parent::setUp();
 
-        if (!array_key_exists('testPrune', $this->skippedTests) && !$this->createCachePool() instanceof PruneableInterface) {
+        if (!\array_key_exists('testPrune', $this->skippedTests) && !$this->createCachePool() instanceof PruneableInterface) {
             $this->skippedTests['testPrune'] = 'Not a pruneable cache pool.';
         }
     }
diff --git a/src/Symfony/Component/Cache/Tests/Psr16CacheTest.php b/src/Symfony/Component/Cache/Tests/Psr16CacheTest.php
index 8fb10f2372..6692d3eb59 100644
--- a/src/Symfony/Component/Cache/Tests/Psr16CacheTest.php
+++ b/src/Symfony/Component/Cache/Tests/Psr16CacheTest.php
@@ -25,7 +25,7 @@ class Psr16CacheTest extends SimpleCacheTest
     {
         parent::setUp();
 
-        if (array_key_exists('testPrune', $this->skippedTests)) {
+        if (\array_key_exists('testPrune', $this->skippedTests)) {
             return;
         }
 
diff --git a/src/Symfony/Component/Cache/Tests/Simple/CacheTestCase.php b/src/Symfony/Component/Cache/Tests/Simple/CacheTestCase.php
index 1a13cbaae8..3c8824869b 100644
--- a/src/Symfony/Component/Cache/Tests/Simple/CacheTestCase.php
+++ b/src/Symfony/Component/Cache/Tests/Simple/CacheTestCase.php
@@ -21,7 +21,7 @@ abstract class CacheTestCase extends SimpleCacheTest
     {
         parent::setUp();
 
-        if (!array_key_exists('testPrune', $this->skippedTests) && !$this->createSimpleCache() instanceof PruneableInterface) {
+        if (!\array_key_exists('testPrune', $this->skippedTests) && !$this->createSimpleCache() instanceof PruneableInterface) {
             $this->skippedTests['testPrune'] = 'Not a pruneable cache pool.';
         }
     }
diff --git a/src/Symfony/Component/Cache/Traits/MemcachedTrait.php b/src/Symfony/Component/Cache/Traits/MemcachedTrait.php
index b83d695937..9c52323943 100644
--- a/src/Symfony/Component/Cache/Traits/MemcachedTrait.php
+++ b/src/Symfony/Component/Cache/Traits/MemcachedTrait.php
@@ -166,7 +166,7 @@ trait MemcachedTrait
             $client->setOption(\Memcached::OPT_BINARY_PROTOCOL, true);
             $client->setOption(\Memcached::OPT_NO_BLOCK, true);
             $client->setOption(\Memcached::OPT_TCP_NODELAY, true);
-            if (!array_key_exists('LIBKETAMA_COMPATIBLE', $options) && !array_key_exists(\Memcached::OPT_LIBKETAMA_COMPATIBLE, $options)) {
+            if (!\array_key_exists('LIBKETAMA_COMPATIBLE', $options) && !\array_key_exists(\Memcached::OPT_LIBKETAMA_COMPATIBLE, $options)) {
                 $client->setOption(\Memcached::OPT_LIBKETAMA_COMPATIBLE, true);
             }
             foreach ($options as $name => $value) {
diff --git a/src/Symfony/Component/Cache/Traits/RedisTrait.php b/src/Symfony/Component/Cache/Traits/RedisTrait.php
index 0276c4fb6d..8da2e257a8 100644
--- a/src/Symfony/Component/Cache/Traits/RedisTrait.php
+++ b/src/Symfony/Component/Cache/Traits/RedisTrait.php
@@ -284,7 +284,7 @@ trait RedisTrait
 
         $result = [];
 
-        if ($this->redis instanceof \Predis\Client) {
+        if ($this->redis instanceof \Predis\Client && $this->redis->getConnection() instanceof ClusterInterface) {
             $values = $this->pipeline(function () use ($ids) {
                 foreach ($ids as $id) {
                     yield 'get' => [$id];
diff --git a/src/Symfony/Component/Config/Definition/ArrayNode.php b/src/Symfony/Component/Config/Definition/ArrayNode.php
index dd908c999e..43697ef279 100644
--- a/src/Symfony/Component/Config/Definition/ArrayNode.php
+++ b/src/Symfony/Component/Config/Definition/ArrayNode.php
@@ -59,7 +59,7 @@ class ArrayNode extends BaseNode implements PrototypeNodeInterface
         $normalized = [];
 
         foreach ($value as $k => $v) {
-            if (false !== strpos($k, '-') && false === strpos($k, '_') && !array_key_exists($normalizedKey = str_replace('-', '_', $k), $value)) {
+            if (false !== strpos($k, '-') && false === strpos($k, '_') && !\array_key_exists($normalizedKey = str_replace('-', '_', $k), $value)) {
                 $normalized[$normalizedKey] = $v;
             } else {
                 $normalized[$k] = $v;
@@ -223,7 +223,7 @@ class ArrayNode extends BaseNode implements PrototypeNodeInterface
         }
 
         foreach ($this->children as $name => $child) {
-            if (!array_key_exists($name, $value)) {
+            if (!\array_key_exists($name, $value)) {
                 if ($child->isRequired()) {
                     $ex = new InvalidConfigurationException(sprintf('The child node "%s" at path "%s" must be configured.', $name, $this->getPath()));
                     $ex->setPath($this->getPath());
@@ -383,7 +383,7 @@ class ArrayNode extends BaseNode implements PrototypeNodeInterface
 
         foreach ($rightSide as $k => $v) {
             // no conflict
-            if (!array_key_exists($k, $leftSide)) {
+            if (!\array_key_exists($k, $leftSide)) {
                 if (!$this->allowNewKeys) {
                     $ex = new InvalidConfigurationException(sprintf('You are not allowed to define new elements for path "%s". Please define all elements for this path in one config file. If you are trying to overwrite an element, make sure you redefine it with the same name.', $this->getPath()));
                     $ex->setPath($this->getPath());
diff --git a/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php b/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
index 43c2b8b731..dca5687a20 100644
--- a/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
+++ b/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
@@ -332,10 +332,10 @@ class ArrayNodeDefinition extends NodeDefinition implements ParentNodeDefinition
      * Allows extra config keys to be specified under an array without
      * throwing an exception.
      *
-     * Those config values are simply ignored and removed from the
-     * resulting array. This should be used only in special cases where
-     * you want to send an entire configuration array through a special
-     * tree that processes only part of the array.
+     * Those config values are ignored and removed from the resulting
+     * array. This should be used only in special cases where you want
+     * to send an entire configuration array through a special tree that
+     * processes only part of the array.
      *
      * @param bool $remove Whether to remove the extra keys
      *
diff --git a/src/Symfony/Component/Config/Definition/PrototypedArrayNode.php b/src/Symfony/Component/Config/Definition/PrototypedArrayNode.php
index 4a3446f52f..dd6ccd94a3 100644
--- a/src/Symfony/Component/Config/Definition/PrototypedArrayNode.php
+++ b/src/Symfony/Component/Config/Definition/PrototypedArrayNode.php
@@ -245,7 +245,7 @@ class PrototypedArrayNode extends ArrayNode
                     // if only "value" is left
                     if (array_keys($v) === ['value']) {
                         $v = $v['value'];
-                        if ($this->prototype instanceof ArrayNode && ($children = $this->prototype->getChildren()) && array_key_exists('value', $children)) {
+                        if ($this->prototype instanceof ArrayNode && ($children = $this->prototype->getChildren()) && \array_key_exists('value', $children)) {
                             $valuePrototype = current($this->valuePrototypes) ?: clone $children['value'];
                             $valuePrototype->parent = $this;
                             $originalClosures = $this->prototype->normalizationClosures;
@@ -258,7 +258,7 @@ class PrototypedArrayNode extends ArrayNode
                     }
                 }
 
-                if (array_key_exists($k, $normalized)) {
+                if (\array_key_exists($k, $normalized)) {
                     $ex = new DuplicateKeyException(sprintf('Duplicate key "%s" for path "%s".', $k, $this->getPath()));
                     $ex->setPath($this->getPath());
 
@@ -301,14 +301,14 @@ class PrototypedArrayNode extends ArrayNode
         }
 
         foreach ($rightSide as $k => $v) {
-            // prototype, and key is irrelevant, so simply append the element
+            // prototype, and key is irrelevant, append the element
             if (null === $this->keyAttribute) {
                 $leftSide[] = $v;
                 continue;
             }
 
             // no conflict
-            if (!array_key_exists($k, $leftSide)) {
+            if (!\array_key_exists($k, $leftSide)) {
                 if (!$this->allowNewKeys) {
                     $ex = new InvalidConfigurationException(sprintf('You are not allowed to define new elements for path "%s". Please define all elements for this path in one config file.', $this->getPath()));
                     $ex->setPath($this->getPath());
diff --git a/src/Symfony/Component/Console/Application.php b/src/Symfony/Component/Console/Application.php
index f96d690589..17df91f994 100644
--- a/src/Symfony/Component/Console/Application.php
+++ b/src/Symfony/Component/Console/Application.php
@@ -199,6 +199,13 @@ class Application
             return 0;
         }
 
+        try {
+            // Makes ArgvInput::getFirstArgument() able to distinguish an option from an argument.
+            $input->bind($this->getDefinition());
+        } catch (ExceptionInterface $e) {
+            // Errors must be ignored, full binding/validation happens later when the command is known.
+        }
+
         $name = $this->getCommandName($input);
         if (true === $input->hasParameterOption(['--help', '-h'], true)) {
             if (!$name) {
diff --git a/src/Symfony/Component/Console/Helper/QuestionHelper.php b/src/Symfony/Component/Console/Helper/QuestionHelper.php
index e367c7d430..cf6447a4bc 100644
--- a/src/Symfony/Component/Console/Helper/QuestionHelper.php
+++ b/src/Symfony/Component/Console/Helper/QuestionHelper.php
@@ -269,6 +269,10 @@ class QuestionHelper extends Helper
 
                 continue;
             } else {
+                if ("\x80" <= $c) {
+                    $c .= fread($inputStream, ["\xC0" => 1, "\xD0" => 1, "\xE0" => 2, "\xF0" => 3][$c & "\xF0"]);
+                }
+
                 $output->write($c);
                 $ret .= $c;
                 ++$i;
diff --git a/src/Symfony/Component/Console/Input/ArgvInput.php b/src/Symfony/Component/Console/Input/ArgvInput.php
index 85ff6f91d8..c56c20c684 100644
--- a/src/Symfony/Component/Console/Input/ArgvInput.php
+++ b/src/Symfony/Component/Console/Input/ArgvInput.php
@@ -257,8 +257,27 @@ class ArgvInput extends Input
      */
     public function getFirstArgument()
     {
-        foreach ($this->tokens as $token) {
+        $isOption = false;
+        foreach ($this->tokens as $i => $token) {
             if ($token && '-' === $token[0]) {
+                if (false !== strpos($token, '=') || !isset($this->tokens[$i + 1])) {
+                    continue;
+                }
+
+                // If it's a long option, consider that everything after "--" is the option name.
+                // Otherwise, use the last char (if it's a short option set, only the last one can take a value with space separator)
+                $name = '-' === $token[1] ? substr($token, 2) : substr($token, -1);
+                if (!isset($this->options[$name]) && !$this->definition->hasShortcut($name)) {
+                    // noop
+                } elseif ((isset($this->options[$name]) || isset($this->options[$name = $this->definition->shortcutToName($name)])) && $this->tokens[$i + 1] === $this->options[$name]) {
+                    $isOption = true;
+                }
+
+                continue;
+            }
+
+            if ($isOption) {
+                $isOption = false;
                 continue;
             }
 
diff --git a/src/Symfony/Component/Console/Input/ArrayInput.php b/src/Symfony/Component/Console/Input/ArrayInput.php
index cf09ff45ec..44c2f0d5c6 100644
--- a/src/Symfony/Component/Console/Input/ArrayInput.php
+++ b/src/Symfony/Component/Console/Input/ArrayInput.php
@@ -19,7 +19,7 @@ use Symfony\Component\Console\Exception\InvalidOptionException;
  *
  * Usage:
  *
- *     $input = new ArrayInput(['name' => 'foo', '--bar' => 'foobar']);
+ *     $input = new ArrayInput(['command' => 'foo:bar', 'foo' => 'bar', '--bar' => 'foobar']);
  *
  * @author Fabien Potencier <fabien@symfony.com>
  */
diff --git a/src/Symfony/Component/Console/Input/Input.php b/src/Symfony/Component/Console/Input/Input.php
index 7a16e0ee4b..c1220316dc 100644
--- a/src/Symfony/Component/Console/Input/Input.php
+++ b/src/Symfony/Component/Console/Input/Input.php
@@ -69,7 +69,7 @@ abstract class Input implements InputInterface, StreamableInputInterface
         $givenArguments = $this->arguments;
 
         $missingArguments = array_filter(array_keys($definition->getArguments()), function ($argument) use ($definition, $givenArguments) {
-            return !array_key_exists($argument, $givenArguments) && $definition->getArgument($argument)->isRequired();
+            return !\array_key_exists($argument, $givenArguments) && $definition->getArgument($argument)->isRequired();
         });
 
         if (\count($missingArguments) > 0) {
@@ -150,7 +150,7 @@ abstract class Input implements InputInterface, StreamableInputInterface
             throw new InvalidArgumentException(sprintf('The "%s" option does not exist.', $name));
         }
 
-        return array_key_exists($name, $this->options) ? $this->options[$name] : $this->definition->getOption($name)->getDefault();
+        return \array_key_exists($name, $this->options) ? $this->options[$name] : $this->definition->getOption($name)->getDefault();
     }
 
     /**
diff --git a/src/Symfony/Component/Console/Input/InputDefinition.php b/src/Symfony/Component/Console/Input/InputDefinition.php
index c7e5c987e5..2189c46282 100644
--- a/src/Symfony/Component/Console/Input/InputDefinition.php
+++ b/src/Symfony/Component/Console/Input/InputDefinition.php
@@ -338,8 +338,10 @@ class InputDefinition
      * @return string The InputOption name
      *
      * @throws InvalidArgumentException When option given does not exist
+     *
+     * @internal
      */
-    private function shortcutToName($shortcut)
+    public function shortcutToName($shortcut)
     {
         if (!isset($this->shortcuts[$shortcut])) {
             throw new InvalidArgumentException(sprintf('The "-%s" option does not exist.', $shortcut));
diff --git a/src/Symfony/Component/Console/Tester/TesterTrait.php b/src/Symfony/Component/Console/Tester/TesterTrait.php
index e5df56d835..7b5e128c49 100644
--- a/src/Symfony/Component/Console/Tester/TesterTrait.php
+++ b/src/Symfony/Component/Console/Tester/TesterTrait.php
@@ -126,7 +126,7 @@ trait TesterTrait
      */
     private function initOutput(array $options)
     {
-        $this->captureStreamsIndependently = array_key_exists('capture_stderr_separately', $options) && $options['capture_stderr_separately'];
+        $this->captureStreamsIndependently = \array_key_exists('capture_stderr_separately', $options) && $options['capture_stderr_separately'];
         if (!$this->captureStreamsIndependently) {
             $this->output = new StreamOutput(fopen('php://memory', 'w', false));
             if (isset($options['decorated'])) {
diff --git a/src/Symfony/Component/Console/Tests/ApplicationTest.php b/src/Symfony/Component/Console/Tests/ApplicationTest.php
index 2aaf9d7dae..e9b1be32a6 100644
--- a/src/Symfony/Component/Console/Tests/ApplicationTest.php
+++ b/src/Symfony/Component/Console/Tests/ApplicationTest.php
@@ -968,6 +968,19 @@ class ApplicationTest extends TestCase
         $this->assertSame('called'.PHP_EOL, $tester->getDisplay(), '->run() does not call interact() if -n is passed');
     }
 
+    public function testRunWithGlobalOptionAndNoCommand()
+    {
+        $application = new Application();
+        $application->setAutoExit(false);
+        $application->setCatchExceptions(false);
+        $application->getDefinition()->addOption(new InputOption('foo', 'f', InputOption::VALUE_OPTIONAL));
+
+        $output = new StreamOutput(fopen('php://memory', 'w', false));
+        $input = new ArgvInput(['cli.php', '--foo', 'bar']);
+
+        $this->assertSame(0, $application->run($input, $output));
+    }
+
     /**
      * Issue #9285.
      *
diff --git a/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php b/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
index 30f1f709d8..e3edbed029 100644
--- a/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
+++ b/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
@@ -237,6 +237,43 @@ class QuestionHelperTest extends AbstractQuestionHelperTest
         $this->assertSame('b', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
     }
 
+    public function getInputs()
+    {
+        return [
+            ['$'], // 1 byte character
+            ['¢'], // 2 bytes character
+            ['€'], // 3 bytes character
+            ['𐍈'], // 4 bytes character
+        ];
+    }
+
+    /**
+     * @dataProvider getInputs
+     */
+    public function testAskWithAutocompleteWithMultiByteCharacter($character)
+    {
+        if (!$this->hasSttyAvailable()) {
+            $this->markTestSkipped('`stty` is required to test autocomplete functionality');
+        }
+
+        $inputStream = $this->getInputStream("$character\n");
+
+        $possibleChoices = [
+            '$' => '1 byte character',
+            '¢' => '2 bytes character',
+            '€' => '3 bytes character',
+            '𐍈' => '4 bytes character',
+        ];
+
+        $dialog = new QuestionHelper();
+        $dialog->setHelperSet(new HelperSet([new FormatterHelper()]));
+
+        $question = new ChoiceQuestion('Please select a character', $possibleChoices);
+        $question->setMaxAttempts(1);
+
+        $this->assertSame($character, $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
+    }
+
     public function testAutocompleteWithTrailingBackslash()
     {
         if (!$this->hasSttyAvailable()) {
diff --git a/src/Symfony/Component/Console/Tests/Input/ArgvInputTest.php b/src/Symfony/Component/Console/Tests/Input/ArgvInputTest.php
index 37caaf2d1c..e20bcdd21b 100644
--- a/src/Symfony/Component/Console/Tests/Input/ArgvInputTest.php
+++ b/src/Symfony/Component/Console/Tests/Input/ArgvInputTest.php
@@ -312,6 +312,14 @@ class ArgvInputTest extends TestCase
 
         $input = new ArgvInput(['cli.php', '-fbbar', 'foo']);
         $this->assertEquals('foo', $input->getFirstArgument(), '->getFirstArgument() returns the first argument from the raw input');
+
+        $input = new ArgvInput(['cli.php', '--foo', 'fooval', 'bar']);
+        $input->bind(new InputDefinition([new InputOption('foo', 'f', InputOption::VALUE_OPTIONAL), new InputArgument('arg')]));
+        $this->assertSame('bar', $input->getFirstArgument());
+
+        $input = new ArgvInput(['cli.php', '-bf', 'fooval', 'argval']);
+        $input->bind(new InputDefinition([new InputOption('bar', 'b', InputOption::VALUE_NONE), new InputOption('foo', 'f', InputOption::VALUE_OPTIONAL), new InputArgument('arg')]));
+        $this->assertSame('argval', $input->getFirstArgument());
     }
 
     public function testHasParameterOption()
diff --git a/src/Symfony/Component/Debug/ErrorHandler.php b/src/Symfony/Component/Debug/ErrorHandler.php
index 083404fb09..2f250cba36 100644
--- a/src/Symfony/Component/Debug/ErrorHandler.php
+++ b/src/Symfony/Component/Debug/ErrorHandler.php
@@ -222,7 +222,7 @@ class ErrorHandler
             }
             if (!\is_array($log)) {
                 $log = [$log];
-            } elseif (!array_key_exists(0, $log)) {
+            } elseif (!\array_key_exists(0, $log)) {
                 throw new \InvalidArgumentException('No logger provided');
             }
             if (null === $log[0]) {
diff --git a/src/Symfony/Component/Debug/Tests/DebugClassLoaderTest.php b/src/Symfony/Component/Debug/Tests/DebugClassLoaderTest.php
index 33739eb276..d9d6e60f9e 100644
--- a/src/Symfony/Component/Debug/Tests/DebugClassLoaderTest.php
+++ b/src/Symfony/Component/Debug/Tests/DebugClassLoaderTest.php
@@ -44,7 +44,7 @@ class DebugClassLoaderTest extends TestCase
 
         $functions = spl_autoload_functions();
         foreach ($functions as $function) {
-            if (is_array($function) && $function[0] instanceof DebugClassLoader) {
+            if (\is_array($function) && $function[0] instanceof DebugClassLoader) {
                 $reflClass = new \ReflectionClass($function[0]);
                 $reflProp = $reflClass->getProperty('classLoader');
                 $reflProp->setAccessible(true);
@@ -205,7 +205,7 @@ class DebugClassLoaderTest extends TestCase
         require __DIR__.'/Fixtures/FinalClasses.php';
 
         $i = 1;
-        while(class_exists($finalClass = __NAMESPACE__.'\\Fixtures\\FinalClass'.$i++, false)) {
+        while (class_exists($finalClass = __NAMESPACE__.'\\Fixtures\\FinalClass'.$i++, false)) {
             spl_autoload_call($finalClass);
             class_exists('Test\\'.__NAMESPACE__.'\\Extends'.substr($finalClass, strrpos($finalClass, '\\') + 1), true);
         }
@@ -371,7 +371,7 @@ class ClassLoader
 
     public function findFile($class)
     {
-        $fixtureDir = __DIR__.DIRECTORY_SEPARATOR.'Fixtures'.DIRECTORY_SEPARATOR;
+        $fixtureDir = __DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR;
 
         if (__NAMESPACE__.'\TestingUnsilencing' === $class) {
             eval('-- parse error --');
@@ -380,7 +380,7 @@ class ClassLoader
         } elseif (__NAMESPACE__.'\TestingCaseMismatch' === $class) {
             eval('namespace '.__NAMESPACE__.'; class TestingCaseMisMatch {}');
         } elseif (__NAMESPACE__.'\Fixtures\Psr4CaseMismatch' === $class) {
-            return $fixtureDir.'psr4'.DIRECTORY_SEPARATOR.'Psr4CaseMismatch.php';
+            return $fixtureDir.'psr4'.\DIRECTORY_SEPARATOR.'Psr4CaseMismatch.php';
         } elseif (__NAMESPACE__.'\Fixtures\NotPSR0' === $class) {
             return $fixtureDir.'reallyNotPsr0.php';
         } elseif (__NAMESPACE__.'\Fixtures\NotPSR0bis' === $class) {
diff --git a/src/Symfony/Component/DependencyInjection/ChildDefinition.php b/src/Symfony/Component/DependencyInjection/ChildDefinition.php
index 095beaec72..f80fa3e8e3 100644
--- a/src/Symfony/Component/DependencyInjection/ChildDefinition.php
+++ b/src/Symfony/Component/DependencyInjection/ChildDefinition.php
@@ -71,7 +71,7 @@ class ChildDefinition extends Definition
      */
     public function getArgument($index)
     {
-        if (array_key_exists('index_'.$index, $this->arguments)) {
+        if (\array_key_exists('index_'.$index, $this->arguments)) {
             return $this->arguments['index_'.$index];
         }
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php b/src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php
index 57614119fc..5aa6680e7e 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/AutowirePass.php
@@ -188,7 +188,7 @@ class AutowirePass extends AbstractRecursivePass
         }
 
         foreach ($parameters as $index => $parameter) {
-            if (array_key_exists($index, $arguments) && '' !== $arguments[$index]) {
+            if (\array_key_exists($index, $arguments) && '' !== $arguments[$index]) {
                 continue;
             }
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php b/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
index 8c34ce4182..aeb9641811 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/RegisterServiceSubscribersPass.php
@@ -43,10 +43,10 @@ class RegisterServiceSubscribersPass extends AbstractRecursivePass
             if ([] !== array_diff(array_keys($attributes), ['id', 'key'])) {
                 throw new InvalidArgumentException(sprintf('The "container.service_subscriber" tag accepts only the "key" and "id" attributes, "%s" given for service "%s".', implode('", "', array_keys($attributes)), $this->currentId));
             }
-            if (!array_key_exists('id', $attributes)) {
+            if (!\array_key_exists('id', $attributes)) {
                 throw new InvalidArgumentException(sprintf('Missing "id" attribute on "container.service_subscriber" tag with key="%s" for service "%s".', $attributes['key'], $this->currentId));
             }
-            if (!array_key_exists('key', $attributes)) {
+            if (!\array_key_exists('key', $attributes)) {
                 $attributes['key'] = $attributes['id'];
             }
             if (isset($serviceMap[$attributes['key']])) {
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveBindingsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveBindingsPass.php
index cf7d96fceb..2238779a25 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveBindingsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveBindingsPass.php
@@ -119,19 +119,19 @@ class ResolveBindingsPass extends AbstractRecursivePass
             }
 
             foreach ($reflectionMethod->getParameters() as $key => $parameter) {
-                if (array_key_exists($key, $arguments) && '' !== $arguments[$key]) {
+                if (\array_key_exists($key, $arguments) && '' !== $arguments[$key]) {
                     continue;
                 }
 
                 $typeHint = ProxyHelper::getTypeHint($reflectionMethod, $parameter);
 
-                if (array_key_exists($k = ltrim($typeHint, '\\').' $'.$parameter->name, $bindings)) {
+                if (\array_key_exists($k = ltrim($typeHint, '\\').' $'.$parameter->name, $bindings)) {
                     $arguments[$key] = $this->getBindingValue($bindings[$k]);
 
                     continue;
                 }
 
-                if (array_key_exists('$'.$parameter->name, $bindings)) {
+                if (\array_key_exists('$'.$parameter->name, $bindings)) {
                     $arguments[$key] = $this->getBindingValue($bindings['$'.$parameter->name]);
 
                     continue;
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/ResolveNamedArgumentsPass.php b/src/Symfony/Component/DependencyInjection/Compiler/ResolveNamedArgumentsPass.php
index 70f2556df5..771c8f7b38 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/ResolveNamedArgumentsPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/ResolveNamedArgumentsPass.php
@@ -77,7 +77,7 @@ class ResolveNamedArgumentsPass extends AbstractRecursivePass
 
                 $typeFound = false;
                 foreach ($parameters as $j => $p) {
-                    if (!array_key_exists($j, $resolvedArguments) && ProxyHelper::getTypeHint($r, $p, true) === $key) {
+                    if (!\array_key_exists($j, $resolvedArguments) && ProxyHelper::getTypeHint($r, $p, true) === $key) {
                         $resolvedArguments[$j] = $argument;
                         $typeFound = true;
                     }
diff --git a/src/Symfony/Component/DependencyInjection/Container.php b/src/Symfony/Component/DependencyInjection/Container.php
index 938c0a8e3c..f1bafe9812 100644
--- a/src/Symfony/Component/DependencyInjection/Container.php
+++ b/src/Symfony/Component/DependencyInjection/Container.php
@@ -385,7 +385,7 @@ class Container implements ResettableContainerInterface
         if (isset($this->resolving[$envName = "env($name)"])) {
             throw new ParameterCircularReferenceException(array_keys($this->resolving));
         }
-        if (isset($this->envCache[$name]) || array_key_exists($name, $this->envCache)) {
+        if (isset($this->envCache[$name]) || \array_key_exists($name, $this->envCache)) {
             return $this->envCache[$name];
         }
         if (!$this->has($id = 'container.env_var_processors_locator')) {
diff --git a/src/Symfony/Component/DependencyInjection/Definition.php b/src/Symfony/Component/DependencyInjection/Definition.php
index 195e2dac68..b79a8c9a82 100644
--- a/src/Symfony/Component/DependencyInjection/Definition.php
+++ b/src/Symfony/Component/DependencyInjection/Definition.php
@@ -269,7 +269,7 @@ class Definition
             throw new OutOfBoundsException(sprintf('The index "%d" is not in the range [0, %d].', $index, \count($this->arguments) - 1));
         }
 
-        if (!array_key_exists($index, $this->arguments)) {
+        if (!\array_key_exists($index, $this->arguments)) {
             throw new OutOfBoundsException(sprintf('The argument "%s" doesn\'t exist.', $index));
         }
 
@@ -314,7 +314,7 @@ class Definition
      */
     public function getArgument($index)
     {
-        if (!array_key_exists($index, $this->arguments)) {
+        if (!\array_key_exists($index, $this->arguments)) {
             throw new OutOfBoundsException(sprintf('The argument "%s" doesn\'t exist.', $index));
         }
 
diff --git a/src/Symfony/Component/DependencyInjection/Dumper/GraphvizDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/GraphvizDumper.php
index b1a9016b0f..08c3e306fb 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/GraphvizDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/GraphvizDumper.php
@@ -171,7 +171,7 @@ class GraphvizDumper extends Dumper
         }
 
         foreach ($container->getServiceIds() as $id) {
-            if (array_key_exists($id, $container->getAliases())) {
+            if (\array_key_exists($id, $container->getAliases())) {
                 continue;
             }
 
diff --git a/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php b/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
index da4e2d9f7a..137fc97798 100644
--- a/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
+++ b/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
@@ -69,7 +69,7 @@ class EnvVarProcessor implements EnvVarProcessorInterface
                 throw new RuntimeException(sprintf('Resolved value of "%s" did not result in an array value.', $next));
             }
 
-            if (!isset($array[$key]) && !array_key_exists($key, $array)) {
+            if (!isset($array[$key]) && !\array_key_exists($key, $array)) {
                 throw new EnvNotFoundException(sprintf('Key "%s" not found in "%s" (resolved from "%s").', $key, json_encode($array), $next));
             }
 
diff --git a/src/Symfony/Component/DependencyInjection/Extension/Extension.php b/src/Symfony/Component/DependencyInjection/Extension/Extension.php
index 25d07ff83b..1285334f58 100644
--- a/src/Symfony/Component/DependencyInjection/Extension/Extension.php
+++ b/src/Symfony/Component/DependencyInjection/Extension/Extension.php
@@ -127,7 +127,7 @@ abstract class Extension implements ExtensionInterface, ConfigurationExtensionIn
      */
     protected function isConfigEnabled(ContainerBuilder $container, array $config)
     {
-        if (!array_key_exists('enabled', $config)) {
+        if (!\array_key_exists('enabled', $config)) {
             throw new InvalidArgumentException("The config array has no 'enabled' key.");
         }
 
diff --git a/src/Symfony/Component/DependencyInjection/LazyProxy/Instantiator/RealServiceInstantiator.php b/src/Symfony/Component/DependencyInjection/LazyProxy/Instantiator/RealServiceInstantiator.php
index 4d6a9f05a9..2e36704080 100644
--- a/src/Symfony/Component/DependencyInjection/LazyProxy/Instantiator/RealServiceInstantiator.php
+++ b/src/Symfony/Component/DependencyInjection/LazyProxy/Instantiator/RealServiceInstantiator.php
@@ -17,7 +17,7 @@ use Symfony\Component\DependencyInjection\Definition;
 /**
  * {@inheritdoc}
  *
- * Noop proxy instantiator - simply produces the real service instead of a proxy instance.
+ * Noop proxy instantiator - produces the real service instead of a proxy instance.
  *
  * @author Marco Pivetta <ocramius@gmail.com>
  */
diff --git a/src/Symfony/Component/DependencyInjection/ParameterBag/ParameterBag.php b/src/Symfony/Component/DependencyInjection/ParameterBag/ParameterBag.php
index 84170577fc..988dbf88cc 100644
--- a/src/Symfony/Component/DependencyInjection/ParameterBag/ParameterBag.php
+++ b/src/Symfony/Component/DependencyInjection/ParameterBag/ParameterBag.php
@@ -68,7 +68,7 @@ class ParameterBag implements ParameterBagInterface
     {
         $name = (string) $name;
 
-        if (!array_key_exists($name, $this->parameters)) {
+        if (!\array_key_exists($name, $this->parameters)) {
             if (!$name) {
                 throw new ParameterNotFoundException($name);
             }
@@ -119,7 +119,7 @@ class ParameterBag implements ParameterBagInterface
      */
     public function has($name)
     {
-        return array_key_exists((string) $name, $this->parameters);
+        return \array_key_exists((string) $name, $this->parameters);
     }
 
     /**
diff --git a/src/Symfony/Component/DomCrawler/Crawler.php b/src/Symfony/Component/DomCrawler/Crawler.php
index c629d8d041..760d3df388 100644
--- a/src/Symfony/Component/DomCrawler/Crawler.php
+++ b/src/Symfony/Component/DomCrawler/Crawler.php
@@ -985,7 +985,7 @@ class Crawler implements \Countable, \IteratorAggregate
         $expressions = [];
 
         // An expression which will never match to replace expressions which cannot match in the crawler
-        // We cannot simply drop
+        // We cannot drop
         $nonMatchingExpression = 'a[name() = "b"]';
 
         $xpathLen = \strlen($xpath);
diff --git a/src/Symfony/Component/DomCrawler/Field/FileFormField.php b/src/Symfony/Component/DomCrawler/Field/FileFormField.php
index af9c6e6f25..9e21c9c4b9 100644
--- a/src/Symfony/Component/DomCrawler/Field/FileFormField.php
+++ b/src/Symfony/Component/DomCrawler/Field/FileFormField.php
@@ -60,7 +60,7 @@ class FileFormField extends FormField
 
             // copy to a tmp location
             $tmp = sys_get_temp_dir().'/'.strtr(substr(base64_encode(hash('sha256', uniqid(mt_rand(), true), true)), 0, 7), '/', '_');
-            if (array_key_exists('extension', $info)) {
+            if (\array_key_exists('extension', $info)) {
                 $tmp .= '.'.$info['extension'];
             }
             if (is_file($tmp)) {
diff --git a/src/Symfony/Component/DomCrawler/FormFieldRegistry.php b/src/Symfony/Component/DomCrawler/FormFieldRegistry.php
index 10c7e8cb36..8f432cfbbb 100644
--- a/src/Symfony/Component/DomCrawler/FormFieldRegistry.php
+++ b/src/Symfony/Component/DomCrawler/FormFieldRegistry.php
@@ -57,7 +57,7 @@ class FormFieldRegistry
         $target = &$this->fields;
         while (\count($segments) > 1) {
             $path = array_shift($segments);
-            if (!array_key_exists($path, $target)) {
+            if (!\array_key_exists($path, $target)) {
                 return;
             }
             $target = &$target[$path];
@@ -80,7 +80,7 @@ class FormFieldRegistry
         $target = &$this->fields;
         while ($segments) {
             $path = array_shift($segments);
-            if (!array_key_exists($path, $target)) {
+            if (!\array_key_exists($path, $target)) {
                 throw new \InvalidArgumentException(sprintf('Unreachable field "%s"', $path));
             }
             $target = &$target[$path];
diff --git a/src/Symfony/Component/EventDispatcher/Debug/WrappedListener.php b/src/Symfony/Component/EventDispatcher/Debug/WrappedListener.php
index 8b3f64a119..8aa3f80a76 100644
--- a/src/Symfony/Component/EventDispatcher/Debug/WrappedListener.php
+++ b/src/Symfony/Component/EventDispatcher/Debug/WrappedListener.php
@@ -30,6 +30,7 @@ class WrappedListener
     private $dispatcher;
     private $pretty;
     private $stub;
+    private $priority;
     private static $hasClassStub;
 
     public function __construct(callable $listener, ?string $name, Stopwatch $stopwatch, EventDispatcherInterface $dispatcher = null)
@@ -98,7 +99,7 @@ class WrappedListener
 
         return [
             'event' => $eventName,
-            'priority' => null !== $this->dispatcher ? $this->dispatcher->getListenerPriority($eventName, $this->listener) : null,
+            'priority' => null !== $this->priority ? $this->priority : (null !== $this->dispatcher ? $this->dispatcher->getListenerPriority($eventName, $this->listener) : null),
             'pretty' => $this->pretty,
             'stub' => $this->stub,
         ];
@@ -106,11 +107,14 @@ class WrappedListener
 
     public function __invoke(Event $event, $eventName, EventDispatcherInterface $dispatcher)
     {
+        $dispatcher = $this->dispatcher ?: $dispatcher;
+
         $this->called = true;
+        $this->priority = $dispatcher->getListenerPriority($eventName, $this->listener);
 
         $e = $this->stopwatch->start($this->name, 'event_listener');
 
-        ($this->optimizedListener)($event, $eventName, $this->dispatcher ?: $dispatcher);
+        ($this->optimizedListener)($event, $eventName, $dispatcher);
 
         if ($e->isStarted()) {
             $e->stop();
diff --git a/src/Symfony/Component/EventDispatcher/GenericEvent.php b/src/Symfony/Component/EventDispatcher/GenericEvent.php
index a9a0a5dfa5..f005e3a3db 100644
--- a/src/Symfony/Component/EventDispatcher/GenericEvent.php
+++ b/src/Symfony/Component/EventDispatcher/GenericEvent.php
@@ -111,7 +111,7 @@ class GenericEvent extends Event implements \ArrayAccess, \IteratorAggregate
      */
     public function hasArgument($key)
     {
-        return array_key_exists($key, $this->arguments);
+        return \array_key_exists($key, $this->arguments);
     }
 
     /**
diff --git a/src/Symfony/Component/Finder/Finder.php b/src/Symfony/Component/Finder/Finder.php
index ab8f92b366..83163f51d5 100644
--- a/src/Symfony/Component/Finder/Finder.php
+++ b/src/Symfony/Component/Finder/Finder.php
@@ -29,7 +29,7 @@ use Symfony\Component\Finder\Iterator\SortableIterator;
  *
  * All rules may be invoked several times.
  *
- * All methods return the current Finder object to allow easy chaining:
+ * All methods return the current Finder object to allow chaining:
  *
  *     $finder = Finder::create()->files()->name('*.php')->in(__DIR__);
  *
@@ -674,12 +674,15 @@ class Finder implements \IteratorAggregate, \Countable
 
     private function searchInDirectory(string $dir): \Iterator
     {
+        $exclude = $this->exclude;
+        $notPaths = $this->notPaths;
+
         if (static::IGNORE_VCS_FILES === (static::IGNORE_VCS_FILES & $this->ignore)) {
-            $this->exclude = array_merge($this->exclude, self::$vcsPatterns);
+            $exclude = array_merge($exclude, self::$vcsPatterns);
         }
 
         if (static::IGNORE_DOT_FILES === (static::IGNORE_DOT_FILES & $this->ignore)) {
-            $this->notPaths[] = '#(^|/)\..+(/|$)#';
+            $notPaths[] = '#(^|/)\..+(/|$)#';
         }
 
         $minDepth = 0;
@@ -712,8 +715,8 @@ class Finder implements \IteratorAggregate, \Countable
 
         $iterator = new Iterator\RecursiveDirectoryIterator($dir, $flags, $this->ignoreUnreadableDirs);
 
-        if ($this->exclude) {
-            $iterator = new Iterator\ExcludeDirectoryFilterIterator($iterator, $this->exclude);
+        if ($exclude) {
+            $iterator = new Iterator\ExcludeDirectoryFilterIterator($iterator, $exclude);
         }
 
         $iterator = new \RecursiveIteratorIterator($iterator, \RecursiveIteratorIterator::SELF_FIRST);
@@ -746,8 +749,8 @@ class Finder implements \IteratorAggregate, \Countable
             $iterator = new Iterator\CustomFilterIterator($iterator, $this->filters);
         }
 
-        if ($this->paths || $this->notPaths) {
-            $iterator = new Iterator\PathFilterIterator($iterator, $this->paths, $this->notPaths);
+        if ($this->paths || $notPaths) {
+            $iterator = new Iterator\PathFilterIterator($iterator, $this->paths, $notPaths);
         }
 
         if ($this->sort || $this->reverseSorting) {
diff --git a/src/Symfony/Component/Finder/Tests/FinderTest.php b/src/Symfony/Component/Finder/Tests/FinderTest.php
index 1b50663e9f..ddff250287 100644
--- a/src/Symfony/Component/Finder/Tests/FinderTest.php
+++ b/src/Symfony/Component/Finder/Tests/FinderTest.php
@@ -421,6 +421,18 @@ class FinderTest extends Iterator\RealIteratorTestCase
         ]), $finder->in(self::$tmpDir)->getIterator());
     }
 
+    public function testIgnoreVCSCanBeDisabledAfterFirstIteration()
+    {
+        $finder = $this->buildFinder();
+        $finder->in(self::$tmpDir);
+        $finder->ignoreDotFiles(false);
+
+        $this->assertIterator($this->toAbsolute(['foo', 'foo/bar.tmp', 'test.php', 'test.py', 'toto', '.bar', '.foo', '.foo/.bar', '.foo/bar', 'foo bar']), $finder->getIterator());
+
+        $finder->ignoreVCS(false);
+        $this->assertIterator($this->toAbsolute(['.git', 'foo', 'foo/bar.tmp', 'test.php', 'test.py', 'toto', 'toto/.git', '.bar', '.foo', '.foo/.bar', '.foo/bar', 'foo bar']), $finder->getIterator());
+    }
+
     public function testIgnoreDotFiles()
     {
         $finder = $this->buildFinder();
@@ -496,6 +508,17 @@ class FinderTest extends Iterator\RealIteratorTestCase
         ]), $finder->in(self::$tmpDir)->getIterator());
     }
 
+    public function testIgnoreDotFilesCanBeDisabledAfterFirstIteration()
+    {
+        $finder = $this->buildFinder();
+        $finder->in(self::$tmpDir);
+
+        $this->assertIterator($this->toAbsolute(['foo', 'foo/bar.tmp', 'test.php', 'test.py', 'toto', 'foo bar']), $finder->getIterator());
+
+        $finder->ignoreDotFiles(false);
+        $this->assertIterator($this->toAbsolute(['foo', 'foo/bar.tmp', 'test.php', 'test.py', 'toto', '.bar', '.foo', '.foo/.bar', '.foo/bar', 'foo bar']), $finder->getIterator());
+    }
+
     public function testSortByName()
     {
         $finder = $this->buildFinder();
diff --git a/src/Symfony/Component/Form/ButtonBuilder.php b/src/Symfony/Component/Form/ButtonBuilder.php
index 38377db30f..d5db836df3 100644
--- a/src/Symfony/Component/Form/ButtonBuilder.php
+++ b/src/Symfony/Component/Form/ButtonBuilder.php
@@ -670,7 +670,7 @@ class ButtonBuilder implements \IteratorAggregate, FormBuilderInterface
      */
     public function hasAttribute($name)
     {
-        return array_key_exists($name, $this->attributes);
+        return \array_key_exists($name, $this->attributes);
     }
 
     /**
@@ -683,7 +683,7 @@ class ButtonBuilder implements \IteratorAggregate, FormBuilderInterface
      */
     public function getAttribute($name, $default = null)
     {
-        return array_key_exists($name, $this->attributes) ? $this->attributes[$name] : $default;
+        return \array_key_exists($name, $this->attributes) ? $this->attributes[$name] : $default;
     }
 
     /**
@@ -777,7 +777,7 @@ class ButtonBuilder implements \IteratorAggregate, FormBuilderInterface
      */
     public function hasOption($name)
     {
-        return array_key_exists($name, $this->options);
+        return \array_key_exists($name, $this->options);
     }
 
     /**
@@ -790,7 +790,7 @@ class ButtonBuilder implements \IteratorAggregate, FormBuilderInterface
      */
     public function getOption($name, $default = null)
     {
-        return array_key_exists($name, $this->options) ? $this->options[$name] : $default;
+        return \array_key_exists($name, $this->options) ? $this->options[$name] : $default;
     }
 
     /**
diff --git a/src/Symfony/Component/Form/ChoiceList/ArrayChoiceList.php b/src/Symfony/Component/Form/ChoiceList/ArrayChoiceList.php
index b24f32a8cd..a3150d275f 100644
--- a/src/Symfony/Component/Form/ChoiceList/ArrayChoiceList.php
+++ b/src/Symfony/Component/Form/ChoiceList/ArrayChoiceList.php
@@ -78,7 +78,7 @@ class ArrayChoiceList implements ChoiceListInterface
             // If a deterministic value generator was passed, use it later
             $this->valueCallback = $value;
         } else {
-            // Otherwise simply generate incrementing integers as values
+            // Otherwise generate incrementing integers as values
             $i = 0;
             $value = function () use (&$i) {
                 return $i++;
@@ -135,7 +135,7 @@ class ArrayChoiceList implements ChoiceListInterface
         $choices = [];
 
         foreach ($values as $i => $givenValue) {
-            if (array_key_exists($givenValue, $this->choices)) {
+            if (\array_key_exists($givenValue, $this->choices)) {
                 $choices[$i] = $this->choices[$givenValue];
             }
         }
diff --git a/src/Symfony/Component/Form/ChoiceList/LazyChoiceList.php b/src/Symfony/Component/Form/ChoiceList/LazyChoiceList.php
index 30cc97551c..b1a671d0c6 100644
--- a/src/Symfony/Component/Form/ChoiceList/LazyChoiceList.php
+++ b/src/Symfony/Component/Form/ChoiceList/LazyChoiceList.php
@@ -32,7 +32,7 @@ class LazyChoiceList implements ChoiceListInterface
     /**
      * The callable creating string values for each choice.
      *
-     * If null, choices are simply cast to strings.
+     * If null, choices are cast to strings.
      *
      * @var callable|null
      */
diff --git a/src/Symfony/Component/Form/Console/Descriptor/JsonDescriptor.php b/src/Symfony/Component/Form/Console/Descriptor/JsonDescriptor.php
index 31d9aa485e..18a288b444 100644
--- a/src/Symfony/Component/Form/Console/Descriptor/JsonDescriptor.php
+++ b/src/Symfony/Component/Form/Console/Descriptor/JsonDescriptor.php
@@ -79,7 +79,7 @@ class JsonDescriptor extends Descriptor
             'allowed_values' => 'allowedValues',
         ];
         foreach ($map as $label => $name) {
-            if (array_key_exists($name, $definition)) {
+            if (\array_key_exists($name, $definition)) {
                 $data[$label] = $definition[$name];
 
                 if ('default' === $name) {
diff --git a/src/Symfony/Component/Form/Console/Descriptor/TextDescriptor.php b/src/Symfony/Component/Form/Console/Descriptor/TextDescriptor.php
index 70ee44520e..90dd8f1dfe 100644
--- a/src/Symfony/Component/Form/Console/Descriptor/TextDescriptor.php
+++ b/src/Symfony/Component/Form/Console/Descriptor/TextDescriptor.php
@@ -114,7 +114,7 @@ class TextDescriptor extends Descriptor
         ];
         $rows = [];
         foreach ($map as $label => $name) {
-            $value = array_key_exists($name, $definition) ? $dump($definition[$name]) : '-';
+            $value = \array_key_exists($name, $definition) ? $dump($definition[$name]) : '-';
             if ('default' === $name && isset($definition['lazy'])) {
                 $value = "Value: $value\n\nClosure(s): ".$dump($definition['lazy']);
             }
diff --git a/src/Symfony/Component/Form/Extension/Core/DataTransformer/IntegerToLocalizedStringTransformer.php b/src/Symfony/Component/Form/Extension/Core/DataTransformer/IntegerToLocalizedStringTransformer.php
index 48aa9978e6..392aa49e51 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataTransformer/IntegerToLocalizedStringTransformer.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataTransformer/IntegerToLocalizedStringTransformer.php
@@ -11,6 +11,8 @@
 
 namespace Symfony\Component\Form\Extension\Core\DataTransformer;
 
+use Symfony\Component\Form\Exception\TransformationFailedException;
+
 /**
  * Transforms between an integer and a localized number with grouping
  * (each thousand) and comma separators.
@@ -42,6 +44,12 @@ class IntegerToLocalizedStringTransformer extends NumberToLocalizedStringTransfo
      */
     public function reverseTransform($value)
     {
+        $decimalSeparator = $this->getNumberFormatter()->getSymbol(\NumberFormatter::DECIMAL_SEPARATOR_SYMBOL);
+
+        if (\is_string($value) && false !== strpos($value, $decimalSeparator)) {
+            throw new TransformationFailedException(sprintf('The value "%s" is not a valid integer.', $value));
+        }
+
         $result = parent::reverseTransform($value);
 
         return null !== $result ? (int) $result : null;
diff --git a/src/Symfony/Component/Form/Extension/Core/Type/FormType.php b/src/Symfony/Component/Form/Extension/Core/Type/FormType.php
index 208d44f5fa..a2bec36949 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/FormType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/FormType.php
@@ -38,7 +38,7 @@ class FormType extends BaseType
     {
         parent::buildForm($builder, $options);
 
-        $isDataOptionSet = array_key_exists('data', $options);
+        $isDataOptionSet = \array_key_exists('data', $options);
 
         $builder
             ->setRequired($options['required'])
diff --git a/src/Symfony/Component/Form/Extension/Validator/Constraints/FormValidator.php b/src/Symfony/Component/Form/Extension/Validator/Constraints/FormValidator.php
index 19fac82957..db96bc731b 100644
--- a/src/Symfony/Component/Form/Extension/Validator/Constraints/FormValidator.php
+++ b/src/Symfony/Component/Form/Extension/Validator/Constraints/FormValidator.php
@@ -41,7 +41,7 @@ class FormValidator extends ConstraintValidator
 
         $validator = $this->context->getValidator()->inContext($this->context);
 
-        if ($form->isSynchronized()) {
+        if ($form->isSubmitted() && $form->isSynchronized()) {
             // Validate the form data only if transformation succeeded
             $groups = self::getValidationGroups($form);
             $data = $form->getData();
@@ -90,7 +90,7 @@ class FormValidator extends ConstraintValidator
                     }
                 }
             }
-        } else {
+        } elseif (!$form->isSynchronized()) {
             $childrenSynchronized = true;
 
             /** @var FormInterface $child */
diff --git a/src/Symfony/Component/Form/Extension/Validator/ViolationMapper/ViolationMapper.php b/src/Symfony/Component/Form/Extension/Validator/ViolationMapper/ViolationMapper.php
index 86a77044d1..659c266ce6 100644
--- a/src/Symfony/Component/Form/Extension/Validator/ViolationMapper/ViolationMapper.php
+++ b/src/Symfony/Component/Form/Extension/Validator/ViolationMapper/ViolationMapper.php
@@ -273,9 +273,6 @@ class ViolationMapper implements ViolationMapperInterface
      */
     private function acceptsErrors(FormInterface $form)
     {
-        // Ignore non-submitted forms. This happens, for example, in PATCH
-        // requests.
-        // https://github.com/symfony/symfony/pull/10567
-        return $form->isSubmitted() && ($this->allowNonSynchronized || $form->isSynchronized());
+        return $this->allowNonSynchronized || $form->isSynchronized();
     }
 }
diff --git a/src/Symfony/Component/Form/Form.php b/src/Symfony/Component/Form/Form.php
index fb0ba683e8..17ecfd6f47 100644
--- a/src/Symfony/Component/Form/Form.php
+++ b/src/Symfony/Component/Form/Form.php
@@ -42,9 +42,9 @@ use Symfony\Component\PropertyAccess\PropertyPath;
  *
  * In most cases, format (1) and format (2) will be the same. For example,
  * a checkbox field uses a Boolean value for both internal processing and
- * storage in the object. In these cases you simply need to set a view
- * transformer to convert between formats (2) and (3). You can do this by
- * calling addViewTransformer().
+ * storage in the object. In these cases you need to set a view transformer
+ * to convert between formats (2) and (3). You can do this by calling
+ * addViewTransformer().
  *
  * In some cases though it makes sense to make format (1) configurable. To
  * demonstrate this, let's extend our above date field to store the value
@@ -574,7 +574,7 @@ class Form implements \IteratorAggregate, FormInterface, ClearableErrorsInterfac
                 }
 
                 foreach ($this->children as $name => $child) {
-                    $isSubmitted = array_key_exists($name, $submittedData);
+                    $isSubmitted = \array_key_exists($name, $submittedData);
 
                     if ($isSubmitted || $clearMissing) {
                         $child->submit($isSubmitted ? $submittedData[$name] : null, $clearMissing);
diff --git a/src/Symfony/Component/Form/FormConfigBuilder.php b/src/Symfony/Component/Form/FormConfigBuilder.php
index 344751b159..1a581d9b8e 100644
--- a/src/Symfony/Component/Form/FormConfigBuilder.php
+++ b/src/Symfony/Component/Form/FormConfigBuilder.php
@@ -418,7 +418,7 @@ class FormConfigBuilder implements FormConfigBuilderInterface
      */
     public function hasAttribute($name)
     {
-        return array_key_exists($name, $this->attributes);
+        return \array_key_exists($name, $this->attributes);
     }
 
     /**
@@ -426,7 +426,7 @@ class FormConfigBuilder implements FormConfigBuilderInterface
      */
     public function getAttribute($name, $default = null)
     {
-        return array_key_exists($name, $this->attributes) ? $this->attributes[$name] : $default;
+        return \array_key_exists($name, $this->attributes) ? $this->attributes[$name] : $default;
     }
 
     /**
@@ -513,7 +513,7 @@ class FormConfigBuilder implements FormConfigBuilderInterface
      */
     public function hasOption($name)
     {
-        return array_key_exists($name, $this->options);
+        return \array_key_exists($name, $this->options);
     }
 
     /**
@@ -521,7 +521,7 @@ class FormConfigBuilder implements FormConfigBuilderInterface
      */
     public function getOption($name, $default = null)
     {
-        return array_key_exists($name, $this->options) ? $this->options[$name] : $default;
+        return \array_key_exists($name, $this->options) ? $this->options[$name] : $default;
     }
 
     /**
diff --git a/src/Symfony/Component/Form/FormFactory.php b/src/Symfony/Component/Form/FormFactory.php
index d474d5903f..b397f9a21f 100644
--- a/src/Symfony/Component/Form/FormFactory.php
+++ b/src/Symfony/Component/Form/FormFactory.php
@@ -63,7 +63,7 @@ class FormFactory implements FormFactoryInterface
      */
     public function createNamedBuilder($name, $type = 'Symfony\Component\Form\Extension\Core\Type\FormType', $data = null, array $options = [])
     {
-        if (null !== $data && !array_key_exists('data', $options)) {
+        if (null !== $data && !\array_key_exists('data', $options)) {
             $options['data'] = $data;
         }
 
diff --git a/src/Symfony/Component/Form/FormRenderer.php b/src/Symfony/Component/Form/FormRenderer.php
index 4b3866fe1c..91e6faa9cc 100644
--- a/src/Symfony/Component/Form/FormRenderer.php
+++ b/src/Symfony/Component/Form/FormRenderer.php
@@ -165,7 +165,7 @@ class FormRenderer implements FormRendererInterface
         // "form_widget" in this example (again, no matter in which theme).
         // If the designer wants to explicitly fallback to "form_widget" in their
         // custom "choice_widget", for example because they only want to wrap
-        // a <div> around the original implementation, they can simply call the
+        // a <div> around the original implementation, they can call the
         // widget() function again to render the block for the parent type.
         //
         // The second kind is implemented in the following blocks.
diff --git a/src/Symfony/Component/Form/NativeRequestHandler.php b/src/Symfony/Component/Form/NativeRequestHandler.php
index b9b4b64b21..cfccf180b9 100644
--- a/src/Symfony/Component/Form/NativeRequestHandler.php
+++ b/src/Symfony/Component/Form/NativeRequestHandler.php
@@ -94,10 +94,10 @@ class NativeRequestHandler implements RequestHandlerInterface
             if ('' === $name) {
                 $params = $_POST;
                 $files = $fixedFiles;
-            } elseif (array_key_exists($name, $_POST) || array_key_exists($name, $fixedFiles)) {
+            } elseif (\array_key_exists($name, $_POST) || \array_key_exists($name, $fixedFiles)) {
                 $default = $form->getConfig()->getCompound() ? [] : null;
-                $params = array_key_exists($name, $_POST) ? $_POST[$name] : $default;
-                $files = array_key_exists($name, $fixedFiles) ? $fixedFiles[$name] : $default;
+                $params = \array_key_exists($name, $_POST) ? $_POST[$name] : $default;
+                $files = \array_key_exists($name, $fixedFiles) ? $fixedFiles[$name] : $default;
             } else {
                 // Don't submit the form if it is not present in the request
                 return;
@@ -115,7 +115,7 @@ class NativeRequestHandler implements RequestHandlerInterface
             return;
         }
 
-        if (\is_array($data) && array_key_exists('_method', $data) && $method === $data['_method'] && !$form->has('_method')) {
+        if (\is_array($data) && \array_key_exists('_method', $data) && $method === $data['_method'] && !$form->has('_method')) {
             unset($data['_method']);
         }
 
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/IntegerToLocalizedStringTransformerTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/IntegerToLocalizedStringTransformerTest.php
index 8d54b064f8..3b1426dfa7 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/IntegerToLocalizedStringTransformerTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/IntegerToLocalizedStringTransformerTest.php
@@ -107,9 +107,7 @@ class IntegerToLocalizedStringTransformerTest extends TestCase
         $transformer = new IntegerToLocalizedStringTransformer();
 
         $this->assertEquals(1, $transformer->reverseTransform('1'));
-        $this->assertEquals(1, $transformer->reverseTransform('1,5'));
-        $this->assertEquals(1234, $transformer->reverseTransform('1234,5'));
-        $this->assertEquals(12345, $transformer->reverseTransform('12345,912'));
+        $this->assertEquals(12345, $transformer->reverseTransform('12345'));
     }
 
     public function testReverseTransformEmpty()
@@ -147,10 +145,10 @@ class IntegerToLocalizedStringTransformerTest extends TestCase
 
         $transformer = new IntegerToLocalizedStringTransformer(null, true);
 
-        $this->assertEquals(1234, $transformer->reverseTransform('1.234,5'));
-        $this->assertEquals(12345, $transformer->reverseTransform('12.345,912'));
-        $this->assertEquals(1234, $transformer->reverseTransform('1234,5'));
-        $this->assertEquals(12345, $transformer->reverseTransform('12345,912'));
+        $this->assertEquals(1234, $transformer->reverseTransform('1.234'));
+        $this->assertEquals(12345, $transformer->reverseTransform('12.345'));
+        $this->assertEquals(1234, $transformer->reverseTransform('1234'));
+        $this->assertEquals(12345, $transformer->reverseTransform('12345'));
     }
 
     public function reverseTransformWithRoundingProvider()
@@ -246,6 +244,29 @@ class IntegerToLocalizedStringTransformerTest extends TestCase
         $transformer->reverseTransform('foo');
     }
 
+    /**
+     * @dataProvider floatNumberProvider
+     * @expectedException \Symfony\Component\Form\Exception\TransformationFailedException
+     */
+    public function testReverseTransformExpectsInteger($number, $locale)
+    {
+        IntlTestHelper::requireFullIntl($this, false);
+
+        \Locale::setDefault($locale);
+
+        $transformer = new IntegerToLocalizedStringTransformer();
+
+        $transformer->reverseTransform($number);
+    }
+
+    public function floatNumberProvider()
+    {
+        return [
+            ['12345.912', 'en'],
+            ['1.234,5', 'de_DE'],
+        ];
+    }
+
     /**
      * @expectedException \Symfony\Component\Form\Exception\TransformationFailedException
      */
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/IntegerTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/IntegerTypeTest.php
index 5a9d195f27..c5c7dd9161 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/IntegerTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/IntegerTypeTest.php
@@ -24,14 +24,15 @@ class IntegerTypeTest extends BaseTypeTest
         parent::setUp();
     }
 
-    public function testSubmitCastsToInteger()
+    public function testSubmitRejectsFloats()
     {
         $form = $this->factory->create(static::TESTED_TYPE);
 
         $form->submit('1.678');
 
-        $this->assertSame(1, $form->getData());
-        $this->assertSame('1', $form->getViewData());
+        $this->assertTrue($form->isSubmitted());
+        $this->assertFalse($form->isValid());
+        $this->assertFalse($form->isSynchronized());
     }
 
     public function testSubmitNull($expected = null, $norm = null, $view = null)
diff --git a/src/Symfony/Component/Form/Tests/Extension/Validator/Constraints/FormValidatorTest.php b/src/Symfony/Component/Form/Tests/Extension/Validator/Constraints/FormValidatorTest.php
index a342ab21fa..9a8b5c259e 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Validator/Constraints/FormValidatorTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Validator/Constraints/FormValidatorTest.php
@@ -61,9 +61,8 @@ class FormValidatorTest extends ConstraintValidatorTestCase
     {
         $object = new \stdClass();
         $options = ['validation_groups' => ['group1', 'group2']];
-        $form = $this->getBuilder('name', '\stdClass', $options)
-            ->setData($object)
-            ->getForm();
+        $form = $this->getCompoundForm($object, $options);
+        $form->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['group1', 'group2']);
 
@@ -82,9 +81,8 @@ class FormValidatorTest extends ConstraintValidatorTestCase
             'validation_groups' => ['group1', 'group2'],
             'constraints' => [$constraint1, $constraint2],
         ];
-        $form = $this->getBuilder('name', '\stdClass', $options)
-            ->setData($object)
-            ->getForm();
+        $form = $this->getCompoundForm($object, $options);
+        $form->submit([]);
 
         // First default constraints
         $this->expectValidateAt(0, 'data', $object, ['group1', 'group2']);
@@ -110,10 +108,9 @@ class FormValidatorTest extends ConstraintValidatorTestCase
             'validation_groups' => ['group1', 'group2'],
             'constraints' => [new Valid()],
         ];
-        $form = $this->getBuilder('name', '\stdClass', $options)->getForm();
+        $form = $this->getCompoundForm($object, $options);
         $parent->add($form);
-
-        $form->setData($object);
+        $parent->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['group1', 'group2']);
 
@@ -146,8 +143,8 @@ class FormValidatorTest extends ConstraintValidatorTestCase
     public function testMissingConstraintIndex()
     {
         $object = new \stdClass();
-        $form = new FormBuilder('name', '\stdClass', $this->dispatcher, $this->factory);
-        $form = $form->setData($object)->getForm();
+        $form = $this->getCompoundForm($object);
+        $form->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['Default']);
 
@@ -170,10 +167,9 @@ class FormValidatorTest extends ConstraintValidatorTestCase
             'validation_groups' => ['group1', 'group2'],
             'constraints' => [$constraint1, $constraint2],
         ];
-        $form = $this->getBuilder('name', '\stdClass', $options)
-            ->setData($object)
-            ->getForm();
+        $form = $this->getCompoundForm($object, $options);
         $parent->add($form);
+        $parent->submit([]);
 
         $this->expectValidateValueAt(0, 'data', $object, $constraint1, 'group1');
         $this->expectValidateValueAt(1, 'data', $object, $constraint2, 'group2');
@@ -361,9 +357,8 @@ class FormValidatorTest extends ConstraintValidatorTestCase
     {
         $object = new \stdClass();
         $options = ['validation_groups' => new GroupSequence(['group1', 'group2'])];
-        $form = $this->getBuilder('name', '\stdClass', $options)
-            ->setData($object)
-            ->getForm();
+        $form = $this->getCompoundForm($object, $options);
+        $form->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, new GroupSequence(['group1', 'group2']));
         $this->expectValidateAt(1, 'data', $object, new GroupSequence(['group1', 'group2']));
@@ -377,9 +372,8 @@ class FormValidatorTest extends ConstraintValidatorTestCase
     {
         $object = new \stdClass();
         $options = ['validation_groups' => [$this, 'getValidationGroups']];
-        $form = $this->getBuilder('name', '\stdClass', $options)
-            ->setData($object)
-            ->getForm();
+        $form = $this->getCompoundForm($object, $options);
+        $form->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['group1', 'group2']);
 
@@ -392,9 +386,8 @@ class FormValidatorTest extends ConstraintValidatorTestCase
     {
         $object = new \stdClass();
         $options = ['validation_groups' => 'header'];
-        $form = $this->getBuilder('name', '\stdClass', $options)
-            ->setData($object)
-            ->getForm();
+        $form = $this->getCompoundForm($object, $options);
+        $form->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['header']);
 
@@ -409,9 +402,8 @@ class FormValidatorTest extends ConstraintValidatorTestCase
         $options = ['validation_groups' => function (FormInterface $form) {
             return ['group1', 'group2'];
         }];
-        $form = $this->getBuilder('name', '\stdClass', $options)
-            ->setData($object)
-            ->getForm();
+        $form = $this->getCompoundForm($object, $options);
+        $form->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['group1', 'group2']);
 
@@ -455,7 +447,7 @@ class FormValidatorTest extends ConstraintValidatorTestCase
             ->setCompound(true)
             ->setDataMapper(new PropertyPathMapper())
             ->getForm();
-        $form = $this->getForm('name', '\stdClass', [
+        $form = $this->getCompoundForm($object, [
             'validation_groups' => 'form_group',
             'constraints' => [new Valid()],
         ]);
@@ -465,7 +457,7 @@ class FormValidatorTest extends ConstraintValidatorTestCase
             'validation_groups' => 'button_group',
         ]));
 
-        $form->setData($object);
+        $parent->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['form_group']);
 
@@ -484,10 +476,9 @@ class FormValidatorTest extends ConstraintValidatorTestCase
             ->setDataMapper(new PropertyPathMapper())
             ->getForm();
         $formOptions = ['constraints' => [new Valid()]];
-        $form = $this->getBuilder('name', '\stdClass', $formOptions)->getForm();
+        $form = $this->getCompoundForm($object, $formOptions);
         $parent->add($form);
-
-        $form->setData($object);
+        $parent->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['group']);
 
@@ -506,10 +497,9 @@ class FormValidatorTest extends ConstraintValidatorTestCase
             ->setDataMapper(new PropertyPathMapper())
             ->getForm();
         $formOptions = ['constraints' => [new Valid()]];
-        $form = $this->getBuilder('name', '\stdClass', $formOptions)->getForm();
+        $form = $this->getCompoundForm($object, $formOptions);
         $parent->add($form);
-
-        $form->setData($object);
+        $parent->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['group1', 'group2']);
 
@@ -523,7 +513,7 @@ class FormValidatorTest extends ConstraintValidatorTestCase
         $object = new \stdClass();
 
         $parentOptions = [
-            'validation_groups' => function (FormInterface $form) {
+            'validation_groups' => function () {
                 return ['group1', 'group2'];
             },
         ];
@@ -532,10 +522,9 @@ class FormValidatorTest extends ConstraintValidatorTestCase
             ->setDataMapper(new PropertyPathMapper())
             ->getForm();
         $formOptions = ['constraints' => [new Valid()]];
-        $form = $this->getBuilder('name', '\stdClass', $formOptions)->getForm();
+        $form = $this->getCompoundForm($object, $formOptions);
         $parent->add($form);
-
-        $form->setData($object);
+        $parent->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['group1', 'group2']);
 
@@ -547,9 +536,8 @@ class FormValidatorTest extends ConstraintValidatorTestCase
     public function testAppendPropertyPath()
     {
         $object = new \stdClass();
-        $form = $this->getBuilder('name', '\stdClass')
-            ->setData($object)
-            ->getForm();
+        $form = $this->getCompoundForm($object);
+        $form->submit([]);
 
         $this->expectValidateAt(0, 'data', $object, ['Default']);
 
@@ -683,6 +671,15 @@ class FormValidatorTest extends ConstraintValidatorTestCase
         return $this->getBuilder($name, $dataClass, $options)->getForm();
     }
 
+    private function getCompoundForm($data, array $options = [])
+    {
+        return $this->getBuilder('name', \get_class($data), $options)
+            ->setData($data)
+            ->setCompound(true)
+            ->setDataMapper(new PropertyPathMapper())
+            ->getForm();
+    }
+
     private function getSubmitButton($name = 'name', array $options = [])
     {
         $builder = new SubmitButtonBuilder($name, $options);
diff --git a/src/Symfony/Component/Form/Tests/Extension/Validator/ValidatorExtensionTest.php b/src/Symfony/Component/Form/Tests/Extension/Validator/ValidatorExtensionTest.php
index b526650ea0..136086a5e5 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Validator/ValidatorExtensionTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Validator/ValidatorExtensionTest.php
@@ -12,12 +12,19 @@
 namespace Symfony\Component\Form\Tests\Extension\Validator;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Form\AbstractType;
 use Symfony\Component\Form\Extension\Validator\Constraints\Form as FormConstraint;
 use Symfony\Component\Form\Extension\Validator\ValidatorExtension;
 use Symfony\Component\Form\Extension\Validator\ValidatorTypeGuesser;
 use Symfony\Component\Form\Form;
+use Symfony\Component\Form\FormBuilderInterface;
+use Symfony\Component\Form\FormFactoryBuilder;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+use Symfony\Component\Validator\Constraints\NotBlank;
 use Symfony\Component\Validator\Mapping\CascadingStrategy;
 use Symfony\Component\Validator\Mapping\ClassMetadata;
+use Symfony\Component\Validator\Mapping\Factory\LazyLoadingMetadataFactory;
+use Symfony\Component\Validator\Mapping\Loader\StaticMethodLoader;
 use Symfony\Component\Validator\Mapping\TraversalStrategy;
 use Symfony\Component\Validator\Tests\Fixtures\FakeMetadataFactory;
 use Symfony\Component\Validator\Validation;
@@ -45,4 +52,78 @@ class ValidatorExtensionTest extends TestCase
         $this->assertSame(CascadingStrategy::CASCADE, $metadata->getPropertyMetadata('children')[0]->cascadingStrategy);
         $this->assertSame(TraversalStrategy::IMPLICIT, $metadata->getPropertyMetadata('children')[0]->traversalStrategy);
     }
+
+    public function testDataConstraintsInvalidateFormEvenIfFieldIsNotSubmitted()
+    {
+        $form = $this->createForm(FooType::class);
+        $form->submit(['baz' => 'foobar'], false);
+
+        $this->assertTrue($form->isSubmitted());
+        $this->assertFalse($form->isValid());
+        $this->assertFalse($form->get('bar')->isSubmitted());
+        $this->assertCount(1, $form->get('bar')->getErrors());
+    }
+
+    public function testFieldConstraintsDoNotInvalidateFormIfFieldIsNotSubmitted()
+    {
+        $form = $this->createForm(FooType::class);
+        $form->submit(['bar' => 'foobar'], false);
+
+        $this->assertTrue($form->isSubmitted());
+        $this->assertTrue($form->isValid());
+    }
+
+    public function testFieldConstraintsInvalidateFormIfFieldIsSubmitted()
+    {
+        $form = $this->createForm(FooType::class);
+        $form->submit(['bar' => 'foobar', 'baz' => ''], false);
+
+        $this->assertTrue($form->isSubmitted());
+        $this->assertFalse($form->isValid());
+        $this->assertTrue($form->get('bar')->isSubmitted());
+        $this->assertTrue($form->get('bar')->isValid());
+        $this->assertTrue($form->get('baz')->isSubmitted());
+        $this->assertFalse($form->get('baz')->isValid());
+    }
+
+    private function createForm($type)
+    {
+        $validator = Validation::createValidatorBuilder()
+            ->setMetadataFactory(new LazyLoadingMetadataFactory(new StaticMethodLoader()))
+            ->getValidator();
+        $formFactoryBuilder = new FormFactoryBuilder();
+        $formFactoryBuilder->addExtension(new ValidatorExtension($validator));
+        $formFactory = $formFactoryBuilder->getFormFactory();
+
+        return $formFactory->create($type);
+    }
+}
+
+class Foo
+{
+    public $bar;
+    public $baz;
+
+    public static function loadValidatorMetadata(ClassMetadata $metadata)
+    {
+        $metadata->addPropertyConstraint('bar', new NotBlank());
+    }
+}
+
+class FooType extends AbstractType
+{
+    public function buildForm(FormBuilderInterface $builder, array $options)
+    {
+        $builder
+            ->add('bar')
+            ->add('baz', null, [
+                'constraints' => [new NotBlank()],
+            ])
+        ;
+    }
+
+    public function configureOptions(OptionsResolver $resolver)
+    {
+        $resolver->setDefault('data_class', Foo::class);
+    }
 }
diff --git a/src/Symfony/Component/Form/Tests/Extension/Validator/ViolationMapper/ViolationMapperTest.php b/src/Symfony/Component/Form/Tests/Extension/Validator/ViolationMapper/ViolationMapperTest.php
index 5d0afa238c..2fa3e92892 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Validator/ViolationMapper/ViolationMapperTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Validator/ViolationMapper/ViolationMapperTest.php
@@ -205,7 +205,7 @@ class ViolationMapperTest extends TestCase
         $this->assertCount(0, $grandChild->getErrors(), $grandChild->getName().' should not have an error, but has one');
     }
 
-    public function testAbortMappingIfNotSubmitted()
+    public function testMappingIfNotSubmitted()
     {
         $violation = $this->getConstraintViolation('children[address].data.street');
         $parent = $this->getForm('parent');
@@ -225,10 +225,10 @@ class ViolationMapperTest extends TestCase
 
         $this->assertCount(0, $parent->getErrors(), $parent->getName().' should not have an error, but has one');
         $this->assertCount(0, $child->getErrors(), $child->getName().' should not have an error, but has one');
-        $this->assertCount(0, $grandChild->getErrors(), $grandChild->getName().' should not have an error, but has one');
+        $this->assertCount(1, $grandChild->getErrors(), $grandChild->getName().' should have one error');
     }
 
-    public function testAbortDotRuleMappingIfNotSubmitted()
+    public function testDotRuleMappingIfNotSubmitted()
     {
         $violation = $this->getConstraintViolation('data.address');
         $parent = $this->getForm('parent');
@@ -250,7 +250,7 @@ class ViolationMapperTest extends TestCase
 
         $this->assertCount(0, $parent->getErrors(), $parent->getName().' should not have an error, but has one');
         $this->assertCount(0, $child->getErrors(), $child->getName().' should not have an error, but has one');
-        $this->assertCount(0, $grandChild->getErrors(), $grandChild->getName().' should not have an error, but has one');
+        $this->assertCount(1, $grandChild->getErrors(), $grandChild->getName().' should have one error');
     }
 
     public function provideDefaultTests()
diff --git a/src/Symfony/Component/Form/Tests/Fixtures/CustomArrayObject.php b/src/Symfony/Component/Form/Tests/Fixtures/CustomArrayObject.php
index 39758e7818..006724014a 100644
--- a/src/Symfony/Component/Form/Tests/Fixtures/CustomArrayObject.php
+++ b/src/Symfony/Component/Form/Tests/Fixtures/CustomArrayObject.php
@@ -26,7 +26,7 @@ class CustomArrayObject implements \ArrayAccess, \IteratorAggregate, \Countable,
 
     public function offsetExists($offset)
     {
-        return array_key_exists($offset, $this->array);
+        return \array_key_exists($offset, $this->array);
     }
 
     public function offsetGet($offset)
diff --git a/src/Symfony/Component/Form/Tests/Fixtures/FixedDataTransformer.php b/src/Symfony/Component/Form/Tests/Fixtures/FixedDataTransformer.php
index e768b1d7cf..2939116096 100644
--- a/src/Symfony/Component/Form/Tests/Fixtures/FixedDataTransformer.php
+++ b/src/Symfony/Component/Form/Tests/Fixtures/FixedDataTransformer.php
@@ -25,7 +25,7 @@ class FixedDataTransformer implements DataTransformerInterface
 
     public function transform($value)
     {
-        if (!array_key_exists($value, $this->mapping)) {
+        if (!\array_key_exists($value, $this->mapping)) {
             throw new TransformationFailedException(sprintf('No mapping for value "%s"', $value));
         }
 
diff --git a/src/Symfony/Component/HttpFoundation/HeaderBag.php b/src/Symfony/Component/HttpFoundation/HeaderBag.php
index b37a72e47e..fa9d17313c 100644
--- a/src/Symfony/Component/HttpFoundation/HeaderBag.php
+++ b/src/Symfony/Component/HttpFoundation/HeaderBag.php
@@ -112,7 +112,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
         $key = str_replace('_', '-', strtolower($key));
         $headers = $this->all();
 
-        if (!array_key_exists($key, $headers)) {
+        if (!\array_key_exists($key, $headers)) {
             if (null === $default) {
                 return $first ? null : [];
             }
@@ -168,7 +168,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
      */
     public function has($key)
     {
-        return array_key_exists(str_replace('_', '-', strtolower($key)), $this->all());
+        return \array_key_exists(str_replace('_', '-', strtolower($key)), $this->all());
     }
 
     /**
@@ -245,7 +245,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
      */
     public function hasCacheControlDirective($key)
     {
-        return array_key_exists($key, $this->cacheControl);
+        return \array_key_exists($key, $this->cacheControl);
     }
 
     /**
@@ -257,7 +257,7 @@ class HeaderBag implements \IteratorAggregate, \Countable
      */
     public function getCacheControlDirective($key)
     {
-        return array_key_exists($key, $this->cacheControl) ? $this->cacheControl[$key] : null;
+        return \array_key_exists($key, $this->cacheControl) ? $this->cacheControl[$key] : null;
     }
 
     /**
diff --git a/src/Symfony/Component/HttpFoundation/ParameterBag.php b/src/Symfony/Component/HttpFoundation/ParameterBag.php
index 3c6ba46a6a..f05e4a2154 100644
--- a/src/Symfony/Component/HttpFoundation/ParameterBag.php
+++ b/src/Symfony/Component/HttpFoundation/ParameterBag.php
@@ -81,7 +81,7 @@ class ParameterBag implements \IteratorAggregate, \Countable
      */
     public function get($key, $default = null)
     {
-        return array_key_exists($key, $this->parameters) ? $this->parameters[$key] : $default;
+        return \array_key_exists($key, $this->parameters) ? $this->parameters[$key] : $default;
     }
 
     /**
@@ -104,7 +104,7 @@ class ParameterBag implements \IteratorAggregate, \Countable
      */
     public function has($key)
     {
-        return array_key_exists($key, $this->parameters);
+        return \array_key_exists($key, $this->parameters);
     }
 
     /**
diff --git a/src/Symfony/Component/HttpFoundation/RedirectResponse.php b/src/Symfony/Component/HttpFoundation/RedirectResponse.php
index 22e5fbb2d0..f685856584 100644
--- a/src/Symfony/Component/HttpFoundation/RedirectResponse.php
+++ b/src/Symfony/Component/HttpFoundation/RedirectResponse.php
@@ -42,7 +42,7 @@ class RedirectResponse extends Response
             throw new \InvalidArgumentException(sprintf('The HTTP status code is not a redirect ("%s" given).', $status));
         }
 
-        if (301 == $status && !array_key_exists('cache-control', $headers)) {
+        if (301 == $status && !\array_key_exists('cache-control', $headers)) {
             $this->headers->remove('cache-control');
         }
     }
diff --git a/src/Symfony/Component/HttpFoundation/Request.php b/src/Symfony/Component/HttpFoundation/Request.php
index 7f44aab1d5..355bf59548 100644
--- a/src/Symfony/Component/HttpFoundation/Request.php
+++ b/src/Symfony/Component/HttpFoundation/Request.php
@@ -617,6 +617,81 @@ class Request
     }
 
     /**
+<<<<<<< HEAD
+=======
+     * Sets the name for trusted headers.
+     *
+     * The following header keys are supported:
+     *
+     *  * Request::HEADER_CLIENT_IP:    defaults to X-Forwarded-For   (see getClientIp())
+     *  * Request::HEADER_CLIENT_HOST:  defaults to X-Forwarded-Host  (see getHost())
+     *  * Request::HEADER_CLIENT_PORT:  defaults to X-Forwarded-Port  (see getPort())
+     *  * Request::HEADER_CLIENT_PROTO: defaults to X-Forwarded-Proto (see getScheme() and isSecure())
+     *  * Request::HEADER_FORWARDED:    defaults to Forwarded         (see RFC 7239)
+     *
+     * Setting an empty value allows to disable the trusted header for the given key.
+     *
+     * @param string $key   The header key
+     * @param string $value The header name
+     *
+     * @throws \InvalidArgumentException
+     *
+     * @deprecated since version 3.3, to be removed in 4.0. Use the $trustedHeaderSet argument of the Request::setTrustedProxies() method instead.
+     */
+    public static function setTrustedHeaderName($key, $value)
+    {
+        @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 3.3 and will be removed in 4.0. Use the $trustedHeaderSet argument of the Request::setTrustedProxies() method instead.', __METHOD__), E_USER_DEPRECATED);
+
+        if ('forwarded' === $key) {
+            $key = self::HEADER_FORWARDED;
+        } elseif ('client_ip' === $key) {
+            $key = self::HEADER_CLIENT_IP;
+        } elseif ('client_host' === $key) {
+            $key = self::HEADER_CLIENT_HOST;
+        } elseif ('client_proto' === $key) {
+            $key = self::HEADER_CLIENT_PROTO;
+        } elseif ('client_port' === $key) {
+            $key = self::HEADER_CLIENT_PORT;
+        } elseif (!\array_key_exists($key, self::$trustedHeaders)) {
+            throw new \InvalidArgumentException(sprintf('Unable to set the trusted header name for key "%s".', $key));
+        }
+
+        self::$trustedHeaders[$key] = $value;
+
+        if (null !== $value) {
+            self::$trustedHeaderNames[$key] = $value;
+            self::$trustedHeaderSet |= $key;
+        } else {
+            self::$trustedHeaderSet &= ~$key;
+        }
+    }
+
+    /**
+     * Gets the trusted proxy header name.
+     *
+     * @param string $key The header key
+     *
+     * @return string The header name
+     *
+     * @throws \InvalidArgumentException
+     *
+     * @deprecated since version 3.3, to be removed in 4.0. Use the Request::getTrustedHeaderSet() method instead.
+     */
+    public static function getTrustedHeaderName($key)
+    {
+        if (2 > \func_num_args() || func_get_arg(1)) {
+            @trigger_error(sprintf('The "%s()" method is deprecated since Symfony 3.3 and will be removed in 4.0. Use the Request::getTrustedHeaderSet() method instead.', __METHOD__), E_USER_DEPRECATED);
+        }
+
+        if (!\array_key_exists($key, self::$trustedHeaders)) {
+            throw new \InvalidArgumentException(sprintf('Unable to get the trusted header name for key "%s".', $key));
+        }
+
+        return self::$trustedHeaders[$key];
+    }
+
+    /**
+>>>>>>> 3.4
      * Normalizes a query string.
      *
      * It builds a normalized query string, where keys/value pairs are alphabetized,
diff --git a/src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php b/src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php
index 9dd8908b27..9e07221933 100644
--- a/src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php
+++ b/src/Symfony/Component/HttpFoundation/ResponseHeaderBag.php
@@ -160,7 +160,7 @@ class ResponseHeaderBag extends HeaderBag
      */
     public function hasCacheControlDirective($key)
     {
-        return array_key_exists($key, $this->computedCacheControl);
+        return \array_key_exists($key, $this->computedCacheControl);
     }
 
     /**
@@ -168,7 +168,7 @@ class ResponseHeaderBag extends HeaderBag
      */
     public function getCacheControlDirective($key)
     {
-        return array_key_exists($key, $this->computedCacheControl) ? $this->computedCacheControl[$key] : null;
+        return \array_key_exists($key, $this->computedCacheControl) ? $this->computedCacheControl[$key] : null;
     }
 
     public function setCookie(Cookie $cookie)
diff --git a/src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBag.php b/src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBag.php
index 7b53e7fc76..ee33698cf0 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Attribute/AttributeBag.php
@@ -63,7 +63,7 @@ class AttributeBag implements AttributeBagInterface, \IteratorAggregate, \Counta
      */
     public function has($name)
     {
-        return array_key_exists($name, $this->attributes);
+        return \array_key_exists($name, $this->attributes);
     }
 
     /**
@@ -71,7 +71,7 @@ class AttributeBag implements AttributeBagInterface, \IteratorAggregate, \Counta
      */
     public function get($name, $default = null)
     {
-        return array_key_exists($name, $this->attributes) ? $this->attributes[$name] : $default;
+        return \array_key_exists($name, $this->attributes) ? $this->attributes[$name] : $default;
     }
 
     /**
@@ -107,7 +107,7 @@ class AttributeBag implements AttributeBagInterface, \IteratorAggregate, \Counta
     public function remove($name)
     {
         $retval = null;
-        if (array_key_exists($name, $this->attributes)) {
+        if (\array_key_exists($name, $this->attributes)) {
             $retval = $this->attributes[$name];
             unset($this->attributes[$name]);
         }
diff --git a/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php b/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
index 7890214e82..162c4b5295 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Attribute/NamespacedAttributeBag.php
@@ -44,7 +44,7 @@ class NamespacedAttributeBag extends AttributeBag
             return false;
         }
 
-        return array_key_exists($name, $attributes);
+        return \array_key_exists($name, $attributes);
     }
 
     /**
@@ -60,7 +60,7 @@ class NamespacedAttributeBag extends AttributeBag
             return $default;
         }
 
-        return array_key_exists($name, $attributes) ? $attributes[$name] : $default;
+        return \array_key_exists($name, $attributes) ? $attributes[$name] : $default;
     }
 
     /**
@@ -81,7 +81,7 @@ class NamespacedAttributeBag extends AttributeBag
         $retval = null;
         $attributes = &$this->resolveAttributePath($name);
         $name = $this->resolveKey($name);
-        if (null !== $attributes && array_key_exists($name, $attributes)) {
+        if (null !== $attributes && \array_key_exists($name, $attributes)) {
             $retval = $attributes[$name];
             unset($attributes[$name]);
         }
@@ -123,7 +123,7 @@ class NamespacedAttributeBag extends AttributeBag
         unset($parts[\count($parts) - 1]);
 
         foreach ($parts as $part) {
-            if (null !== $array && !array_key_exists($part, $array)) {
+            if (null !== $array && !\array_key_exists($part, $array)) {
                 if (!$writeContext) {
                     $null = null;
 
diff --git a/src/Symfony/Component/HttpFoundation/Session/Flash/AutoExpireFlashBag.php b/src/Symfony/Component/HttpFoundation/Session/Flash/AutoExpireFlashBag.php
index 782665caff..6502f3d501 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Flash/AutoExpireFlashBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Flash/AutoExpireFlashBag.php
@@ -53,7 +53,7 @@ class AutoExpireFlashBag implements FlashBagInterface
         // The logic: messages from the last request will be stored in new, so we move them to previous
         // This request we will show what is in 'display'.  What is placed into 'new' this time round will
         // be moved to display next time round.
-        $this->flashes['display'] = array_key_exists('new', $this->flashes) ? $this->flashes['new'] : [];
+        $this->flashes['display'] = \array_key_exists('new', $this->flashes) ? $this->flashes['new'] : [];
         $this->flashes['new'] = [];
     }
 
@@ -78,7 +78,7 @@ class AutoExpireFlashBag implements FlashBagInterface
      */
     public function peekAll()
     {
-        return array_key_exists('display', $this->flashes) ? (array) $this->flashes['display'] : [];
+        return \array_key_exists('display', $this->flashes) ? (array) $this->flashes['display'] : [];
     }
 
     /**
@@ -132,7 +132,7 @@ class AutoExpireFlashBag implements FlashBagInterface
      */
     public function has($type)
     {
-        return array_key_exists($type, $this->flashes['display']) && $this->flashes['display'][$type];
+        return \array_key_exists($type, $this->flashes['display']) && $this->flashes['display'][$type];
     }
 
     /**
diff --git a/src/Symfony/Component/HttpFoundation/Session/Flash/FlashBag.php b/src/Symfony/Component/HttpFoundation/Session/Flash/FlashBag.php
index 9674e3514b..c6b7ce354c 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Flash/FlashBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Flash/FlashBag.php
@@ -123,7 +123,7 @@ class FlashBag implements FlashBagInterface
      */
     public function has($type)
     {
-        return array_key_exists($type, $this->flashes) && $this->flashes[$type];
+        return \array_key_exists($type, $this->flashes) && $this->flashes[$type];
     }
 
     /**
diff --git a/src/Symfony/Component/HttpKernel/EventListener/ExceptionListener.php b/src/Symfony/Component/HttpKernel/EventListener/ExceptionListener.php
index dd00797f5f..811f99bd9d 100644
--- a/src/Symfony/Component/HttpKernel/EventListener/ExceptionListener.php
+++ b/src/Symfony/Component/HttpKernel/EventListener/ExceptionListener.php
@@ -79,13 +79,12 @@ class ExceptionListener implements EventSubscriberInterface
 
             $this->logException($e, sprintf('Exception thrown when handling an exception (%s: %s at %s line %s)', $f->getClass(), $f->getMessage(), $e->getFile(), $e->getLine()));
 
-            $wrapper = $e;
-
-            while ($prev = $wrapper->getPrevious()) {
+            $prev = $e;
+            do {
                 if ($exception === $wrapper = $prev) {
                     throw $e;
                 }
-            }
+            } while ($prev = $wrapper->getPrevious());
 
             $prev = new \ReflectionProperty($wrapper instanceof \Exception ? \Exception::class : \Error::class, 'previous');
             $prev->setAccessible(true);
diff --git a/src/Symfony/Component/HttpKernel/Fragment/InlineFragmentRenderer.php b/src/Symfony/Component/HttpKernel/Fragment/InlineFragmentRenderer.php
index 5ee09fb1a7..c01b09559a 100644
--- a/src/Symfony/Component/HttpKernel/Fragment/InlineFragmentRenderer.php
+++ b/src/Symfony/Component/HttpKernel/Fragment/InlineFragmentRenderer.php
@@ -80,7 +80,7 @@ class InlineFragmentRenderer extends RoutableFragmentRenderer
             return SubRequestHandler::handle($this->kernel, $subRequest, HttpKernelInterface::SUB_REQUEST, false);
         } catch (\Exception $e) {
             // we dispatch the exception event to trigger the logging
-            // the response that comes back is simply ignored
+            // the response that comes back is ignored
             if (isset($options['ignore_errors']) && $options['ignore_errors'] && $this->dispatcher) {
                 $event = new GetResponseForExceptionEvent($this->kernel, $request, HttpKernelInterface::SUB_REQUEST, $e);
 
diff --git a/src/Symfony/Component/HttpKernel/Tests/DataCollector/RequestDataCollectorTest.php b/src/Symfony/Component/HttpKernel/Tests/DataCollector/RequestDataCollectorTest.php
index ec86792e93..f32247fd32 100644
--- a/src/Symfony/Component/HttpKernel/Tests/DataCollector/RequestDataCollectorTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/DataCollector/RequestDataCollectorTest.php
@@ -351,15 +351,15 @@ class RequestDataCollectorTest extends TestCase
 
     public function provideJsonContentTypes()
     {
-        return array(
-            array('text/csv', false),
-            array('application/json', true),
-            array('application/JSON', true),
-            array('application/hal+json', true),
-            array('application/xml+json', true),
-            array('application/xml', false),
-            array('', false),
-        );
+        return [
+            ['text/csv', false],
+            ['application/json', true],
+            ['application/JSON', true],
+            ['application/hal+json', true],
+            ['application/xml+json', true],
+            ['application/xml', false],
+            ['', false],
+        ];
     }
 
     /**
@@ -368,7 +368,7 @@ class RequestDataCollectorTest extends TestCase
     public function testGetPrettyJsonValidity($content, $expected)
     {
         $response = $this->createResponse();
-        $request = Request::create('/', 'POST', array(), array(), array(), array(), $content);
+        $request = Request::create('/', 'POST', [], [], [], [], $content);
 
         $c = new RequestDataCollector();
         $c->collect($request, $response);
@@ -378,13 +378,13 @@ class RequestDataCollectorTest extends TestCase
 
     public function providePrettyJson()
     {
-        return array(
-            array('null', 'null'),
-            array('{ "foo": "bar" }', '{
+        return [
+            ['null', 'null'],
+            ['{ "foo": "bar" }', '{
     "foo": "bar"
-}'),
-            array('{ "abc" }', null),
-            array('', null),
-        );
+}'],
+            ['{ "abc" }', null],
+            ['', null],
+        ];
     }
 }
diff --git a/src/Symfony/Component/Intl/Data/Generator/LocaleDataGenerator.php b/src/Symfony/Component/Intl/Data/Generator/LocaleDataGenerator.php
index d1fc3c01e0..84940e63ae 100644
--- a/src/Symfony/Component/Intl/Data/Generator/LocaleDataGenerator.php
+++ b/src/Symfony/Component/Intl/Data/Generator/LocaleDataGenerator.php
@@ -164,7 +164,7 @@ class LocaleDataGenerator
         // the name sorting
         // $name = $this->langBundle->getLanguageName($displayLocale, $lang, $region);
 
-        // Some languages are simply not translated
+        // Some languages are not translated
         // Example: "az" (Azerbaijani) has no translation in "af" (Afrikaans)
         if (null === ($name = $this->languageDataProvider->getName($lang, $displayLocale))) {
             return;
diff --git a/src/Symfony/Component/Intl/Data/Util/RecursiveArrayAccess.php b/src/Symfony/Component/Intl/Data/Util/RecursiveArrayAccess.php
index c133932c9e..09dd551daf 100644
--- a/src/Symfony/Component/Intl/Data/Util/RecursiveArrayAccess.php
+++ b/src/Symfony/Component/Intl/Data/Util/RecursiveArrayAccess.php
@@ -25,7 +25,7 @@ class RecursiveArrayAccess
         foreach ($indices as $index) {
             // Use array_key_exists() for arrays, isset() otherwise
             if (\is_array($array)) {
-                if (array_key_exists($index, $array)) {
+                if (\array_key_exists($index, $array)) {
                     $array = $array[$index];
                     continue;
                 }
diff --git a/src/Symfony/Component/Intl/NumberFormatter/NumberFormatter.php b/src/Symfony/Component/Intl/NumberFormatter/NumberFormatter.php
index 247ea5e1d8..c668d9a3c1 100644
--- a/src/Symfony/Component/Intl/NumberFormatter/NumberFormatter.php
+++ b/src/Symfony/Component/Intl/NumberFormatter/NumberFormatter.php
@@ -460,7 +460,7 @@ class NumberFormatter
      */
     public function getSymbol($attr)
     {
-        return array_key_exists($this->style, self::$enSymbols) && array_key_exists($attr, self::$enSymbols[$this->style]) ? self::$enSymbols[$this->style][$attr] : false;
+        return \array_key_exists($this->style, self::$enSymbols) && \array_key_exists($attr, self::$enSymbols[$this->style]) ? self::$enSymbols[$this->style][$attr] : false;
     }
 
     /**
@@ -474,7 +474,7 @@ class NumberFormatter
      */
     public function getTextAttribute($attr)
     {
-        return array_key_exists($this->style, self::$enTextAttributes) && array_key_exists($attr, self::$enTextAttributes[$this->style]) ? self::$enTextAttributes[$this->style][$attr] : false;
+        return \array_key_exists($this->style, self::$enTextAttributes) && \array_key_exists($attr, self::$enTextAttributes[$this->style]) ? self::$enTextAttributes[$this->style][$attr] : false;
     }
 
     /**
diff --git a/src/Symfony/Component/Messenger/Transport/AmqpExt/Connection.php b/src/Symfony/Component/Messenger/Transport/AmqpExt/Connection.php
index d56b105a2b..e576916b8d 100644
--- a/src/Symfony/Component/Messenger/Transport/AmqpExt/Connection.php
+++ b/src/Symfony/Component/Messenger/Transport/AmqpExt/Connection.php
@@ -110,7 +110,7 @@ class Connection
     private static function normalizeQueueArguments(array $arguments): array
     {
         foreach (self::ARGUMENTS_AS_INTEGER as $key) {
-            if (!array_key_exists($key, $arguments)) {
+            if (!\array_key_exists($key, $arguments)) {
                 continue;
             }
 
@@ -256,6 +256,6 @@ class Connection
 
     private function shouldSetup(): bool
     {
-        return !array_key_exists('auto-setup', $this->connectionCredentials) || !\in_array($this->connectionCredentials['auto-setup'], [false, 'false'], true);
+        return !\array_key_exists('auto-setup', $this->connectionCredentials) || !\in_array($this->connectionCredentials['auto-setup'], [false, 'false'], true);
     }
 }
diff --git a/src/Symfony/Component/OptionsResolver/Debug/OptionsResolverIntrospector.php b/src/Symfony/Component/OptionsResolver/Debug/OptionsResolverIntrospector.php
index 3867447a30..ccce082fed 100644
--- a/src/Symfony/Component/OptionsResolver/Debug/OptionsResolverIntrospector.php
+++ b/src/Symfony/Component/OptionsResolver/Debug/OptionsResolverIntrospector.php
@@ -32,7 +32,7 @@ class OptionsResolverIntrospector
                 throw new UndefinedOptionsException(sprintf('The option "%s" does not exist.', $option));
             }
 
-            if (!array_key_exists($option, $this->{$property})) {
+            if (!\array_key_exists($option, $this->{$property})) {
                 throw new NoConfigurationException($message);
             }
 
diff --git a/src/Symfony/Component/OptionsResolver/OptionsResolver.php b/src/Symfony/Component/OptionsResolver/OptionsResolver.php
index 6532fe0a0a..eb0a6c2480 100644
--- a/src/Symfony/Component/OptionsResolver/OptionsResolver.php
+++ b/src/Symfony/Component/OptionsResolver/OptionsResolver.php
@@ -219,7 +219,7 @@ class OptionsResolver implements Options
         // to resolve options with lazy closures, normalizers or validation
         // rules, none of which can exist for undefined options
         // If the option was resolved before, update the resolved value
-        if (!isset($this->defined[$option]) || array_key_exists($option, $this->resolved)) {
+        if (!isset($this->defined[$option]) || \array_key_exists($option, $this->resolved)) {
             $this->resolved[$option] = $value;
         }
 
@@ -259,7 +259,7 @@ class OptionsResolver implements Options
      */
     public function hasDefault($option)
     {
-        return array_key_exists($option, $this->defaults);
+        return \array_key_exists($option, $this->defaults);
     }
 
     /**
@@ -324,7 +324,7 @@ class OptionsResolver implements Options
      */
     public function isMissing($option)
     {
-        return isset($this->required[$option]) && !array_key_exists($option, $this->defaults);
+        return isset($this->required[$option]) && !\array_key_exists($option, $this->defaults);
     }
 
     /**
@@ -800,7 +800,7 @@ class OptionsResolver implements Options
         $triggerDeprecation = 1 === \func_num_args() || \func_get_arg(1);
 
         // Shortcut for resolved options
-        if (isset($this->resolved[$option]) || array_key_exists($option, $this->resolved)) {
+        if (isset($this->resolved[$option]) || \array_key_exists($option, $this->resolved)) {
             if ($triggerDeprecation && isset($this->deprecated[$option]) && (isset($this->given[$option]) || $this->calling) && \is_string($this->deprecated[$option])) {
                 @trigger_error(strtr($this->deprecated[$option], ['%name%' => $option]), E_USER_DEPRECATED);
             }
@@ -809,7 +809,7 @@ class OptionsResolver implements Options
         }
 
         // Check whether the option is set at all
-        if (!isset($this->defaults[$option]) && !array_key_exists($option, $this->defaults)) {
+        if (!isset($this->defaults[$option]) && !\array_key_exists($option, $this->defaults)) {
             if (!isset($this->defined[$option])) {
                 throw new NoSuchOptionException(sprintf('The option "%s" does not exist. Defined options are: "%s".', $option, implode('", "', array_keys($this->defined))));
             }
@@ -1033,7 +1033,7 @@ class OptionsResolver implements Options
             throw new AccessException('Array access is only supported within closures of lazy options and normalizers.');
         }
 
-        return array_key_exists($option, $this->defaults);
+        return \array_key_exists($option, $this->defaults);
     }
 
     /**
diff --git a/src/Symfony/Component/PropertyAccess/PropertyAccessor.php b/src/Symfony/Component/PropertyAccess/PropertyAccessor.php
index aae083e4b7..b7333dac30 100644
--- a/src/Symfony/Component/PropertyAccess/PropertyAccessor.php
+++ b/src/Symfony/Component/PropertyAccess/PropertyAccessor.php
@@ -185,7 +185,7 @@ class PropertyAccessor implements PropertyAccessorInterface
             return;
         }
 
-        if (isset($trace[$i]['file']) && __FILE__ === $trace[$i]['file'] && array_key_exists(0, $trace[$i]['args'])) {
+        if (isset($trace[$i]['file']) && __FILE__ === $trace[$i]['file'] && \array_key_exists(0, $trace[$i]['args'])) {
             $pos = strpos($message, $delim = 'must be of the type ') ?: (strpos($message, $delim = 'must be an instance of ') ?: strpos($message, $delim = 'must implement interface '));
             $pos += \strlen($delim);
             $type = $trace[$i]['args'][0];
@@ -287,7 +287,7 @@ class PropertyAccessor implements PropertyAccessorInterface
             if ($isIndex) {
                 // Create missing nested arrays on demand
                 if (($zval[self::VALUE] instanceof \ArrayAccess && !$zval[self::VALUE]->offsetExists($property)) ||
-                    (\is_array($zval[self::VALUE]) && !isset($zval[self::VALUE][$property]) && !array_key_exists($property, $zval[self::VALUE]))
+                    (\is_array($zval[self::VALUE]) && !isset($zval[self::VALUE][$property]) && !\array_key_exists($property, $zval[self::VALUE]))
                 ) {
                     if (!$ignoreInvalidIndices) {
                         if (!\is_array($zval[self::VALUE])) {
diff --git a/src/Symfony/Component/PropertyAccess/Tests/Fixtures/NonTraversableArrayObject.php b/src/Symfony/Component/PropertyAccess/Tests/Fixtures/NonTraversableArrayObject.php
index 4852e8d58f..4b18e725ae 100644
--- a/src/Symfony/Component/PropertyAccess/Tests/Fixtures/NonTraversableArrayObject.php
+++ b/src/Symfony/Component/PropertyAccess/Tests/Fixtures/NonTraversableArrayObject.php
@@ -26,7 +26,7 @@ class NonTraversableArrayObject implements \ArrayAccess, \Countable, \Serializab
 
     public function offsetExists($offset)
     {
-        return array_key_exists($offset, $this->array);
+        return \array_key_exists($offset, $this->array);
     }
 
     public function offsetGet($offset)
diff --git a/src/Symfony/Component/PropertyAccess/Tests/Fixtures/TraversableArrayObject.php b/src/Symfony/Component/PropertyAccess/Tests/Fixtures/TraversableArrayObject.php
index 9803a11f84..b075286f4a 100644
--- a/src/Symfony/Component/PropertyAccess/Tests/Fixtures/TraversableArrayObject.php
+++ b/src/Symfony/Component/PropertyAccess/Tests/Fixtures/TraversableArrayObject.php
@@ -26,7 +26,7 @@ class TraversableArrayObject implements \ArrayAccess, \IteratorAggregate, \Count
 
     public function offsetExists($offset)
     {
-        return array_key_exists($offset, $this->array);
+        return \array_key_exists($offset, $this->array);
     }
 
     public function offsetGet($offset)
diff --git a/src/Symfony/Component/PropertyInfo/PropertyInfoCacheExtractor.php b/src/Symfony/Component/PropertyInfo/PropertyInfoCacheExtractor.php
index ac883e7c04..0eb9f63a54 100644
--- a/src/Symfony/Component/PropertyInfo/PropertyInfoCacheExtractor.php
+++ b/src/Symfony/Component/PropertyInfo/PropertyInfoCacheExtractor.php
@@ -105,7 +105,7 @@ class PropertyInfoCacheExtractor implements PropertyInfoExtractorInterface, Prop
         // Calling rawurlencode escapes special characters not allowed in PSR-6's keys
         $key = rawurlencode($method.'.'.$serializedArguments);
 
-        if (array_key_exists($key, $this->arrayCache)) {
+        if (\array_key_exists($key, $this->arrayCache)) {
             return $this->arrayCache[$key];
         }
 
diff --git a/src/Symfony/Component/Routing/Generator/UrlGenerator.php b/src/Symfony/Component/Routing/Generator/UrlGenerator.php
index abb5b7e6f0..1871437eae 100644
--- a/src/Symfony/Component/Routing/Generator/UrlGenerator.php
+++ b/src/Symfony/Component/Routing/Generator/UrlGenerator.php
@@ -160,7 +160,7 @@ class UrlGenerator implements UrlGeneratorInterface, ConfigurableRequirementsInt
                 // variable is not important by default
                 $important = $token[5] ?? false;
 
-                if (!$optional || $important || !array_key_exists($varName, $defaults) || (null !== $mergedParams[$varName] && (string) $mergedParams[$varName] !== (string) $defaults[$varName])) {
+                if (!$optional || $important || !\array_key_exists($varName, $defaults) || (null !== $mergedParams[$varName] && (string) $mergedParams[$varName] !== (string) $defaults[$varName])) {
                     // check requirement
                     if (null !== $this->strictRequirements && !preg_match('#^'.$token[2].'$#'.(empty($token[4]) ? '' : 'u'), $mergedParams[$varName])) {
                         if ($this->strictRequirements) {
@@ -216,7 +216,8 @@ class UrlGenerator implements UrlGeneratorInterface, ConfigurableRequirementsInt
             $routeHost = '';
             foreach ($hostTokens as $token) {
                 if ('variable' === $token[0]) {
-                    if (null !== $this->strictRequirements && !preg_match('#^'.$token[2].'$#i'.(empty($token[4]) ? '' : 'u'), $mergedParams[$token[3]])) {
+                    // check requirement (while ignoring look-around patterns)
+                    if (null !== $this->strictRequirements && !preg_match('#^'.preg_replace('/\(\?(?:=|<=|!|<!)((?:[^()\\\\]+|\\\\.|\((?1)\))*)\)/', '', $token[2]).'$#i'.(empty($token[4]) ? '' : 'u'), $mergedParams[$token[3]])) {
                         if ($this->strictRequirements) {
                             throw new InvalidParameterException(strtr($message, ['{parameter}' => $token[3], '{route}' => $name, '{expected}' => $token[2], '{given}' => $mergedParams[$token[3]]]));
                         }
diff --git a/src/Symfony/Component/Routing/RequestContext.php b/src/Symfony/Component/Routing/RequestContext.php
index dc3e4be1e7..591dd15938 100644
--- a/src/Symfony/Component/Routing/RequestContext.php
+++ b/src/Symfony/Component/Routing/RequestContext.php
@@ -306,7 +306,7 @@ class RequestContext
      */
     public function hasParameter($name)
     {
-        return array_key_exists($name, $this->parameters);
+        return \array_key_exists($name, $this->parameters);
     }
 
     /**
diff --git a/src/Symfony/Component/Routing/Route.php b/src/Symfony/Component/Routing/Route.php
index 58675902a1..4e0463b575 100644
--- a/src/Symfony/Component/Routing/Route.php
+++ b/src/Symfony/Component/Routing/Route.php
@@ -327,7 +327,7 @@ class Route implements \Serializable
      */
     public function hasOption($name)
     {
-        return array_key_exists($name, $this->options);
+        return \array_key_exists($name, $this->options);
     }
 
     /**
@@ -396,7 +396,7 @@ class Route implements \Serializable
      */
     public function hasDefault($name)
     {
-        return array_key_exists($name, $this->defaults);
+        return \array_key_exists($name, $this->defaults);
     }
 
     /**
@@ -481,7 +481,7 @@ class Route implements \Serializable
      */
     public function hasRequirement($key)
     {
-        return array_key_exists($key, $this->requirements);
+        return \array_key_exists($key, $this->requirements);
     }
 
     /**
diff --git a/src/Symfony/Component/Routing/Router.php b/src/Symfony/Component/Routing/Router.php
index 34c4d9ce23..3024c9f255 100644
--- a/src/Symfony/Component/Routing/Router.php
+++ b/src/Symfony/Component/Routing/Router.php
@@ -146,7 +146,7 @@ class Router implements RouterInterface, RequestMatcherInterface
         $invalid = [];
         foreach ($options as $key => $value) {
             $this->checkDeprecatedOption($key);
-            if (array_key_exists($key, $this->options)) {
+            if (\array_key_exists($key, $this->options)) {
                 $this->options[$key] = $value;
             } else {
                 $invalid[] = $key;
@@ -168,7 +168,7 @@ class Router implements RouterInterface, RequestMatcherInterface
      */
     public function setOption($key, $value)
     {
-        if (!array_key_exists($key, $this->options)) {
+        if (!\array_key_exists($key, $this->options)) {
             throw new \InvalidArgumentException(sprintf('The Router does not support the "%s" option.', $key));
         }
 
@@ -188,7 +188,7 @@ class Router implements RouterInterface, RequestMatcherInterface
      */
     public function getOption($key)
     {
-        if (!array_key_exists($key, $this->options)) {
+        if (!\array_key_exists($key, $this->options)) {
             throw new \InvalidArgumentException(sprintf('The Router does not support the "%s" option.', $key));
         }
 
diff --git a/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php b/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
index 6a79609917..6ed5aa1787 100644
--- a/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
+++ b/src/Symfony/Component/Routing/Tests/Generator/UrlGeneratorTest.php
@@ -724,6 +724,23 @@ class UrlGeneratorTest extends TestCase
         $this->assertEquals('/app.php/testing#fragment', $url);
     }
 
+    /**
+     * @dataProvider provideLookAroundRequirementsInPath
+     */
+    public function testLookRoundRequirementsInPath($expected, $path, $requirement)
+    {
+        $routes = $this->getRoutes('test', new Route($path, [], ['foo' => $requirement, 'baz' => '.+?']));
+        $this->assertSame($expected, $this->getGenerator($routes)->generate('test', ['foo' => 'a/b', 'baz' => 'c/d/e']));
+    }
+
+    public function provideLookAroundRequirementsInPath()
+    {
+        yield ['/app.php/a/b/b%28ar/c/d/e', '/{foo}/b(ar/{baz}', '.+(?=/b\\(ar/)'];
+        yield ['/app.php/a/b/bar/c/d/e', '/{foo}/bar/{baz}', '.+(?!$)'];
+        yield ['/app.php/bar/a/b/bam/c/d/e', '/bar/{foo}/bam/{baz}', '(?<=/bar/).+'];
+        yield ['/app.php/bar/a/b/bam/c/d/e', '/bar/{foo}/bam/{baz}', '(?<!^).+'];
+    }
+
     protected function getGenerator(RouteCollection $routes, array $parameters = [], $logger = null)
     {
         $context = new RequestContext('/app.php');
diff --git a/src/Symfony/Component/Security/Core/Authentication/Token/AbstractToken.php b/src/Symfony/Component/Security/Core/Authentication/Token/AbstractToken.php
index f879cf8a87..df75ab4b06 100644
--- a/src/Symfony/Component/Security/Core/Authentication/Token/AbstractToken.php
+++ b/src/Symfony/Component/Security/Core/Authentication/Token/AbstractToken.php
@@ -225,7 +225,7 @@ abstract class AbstractToken implements TokenInterface
      */
     public function hasAttribute($name)
     {
-        return array_key_exists($name, $this->attributes);
+        return \array_key_exists($name, $this->attributes);
     }
 
     /**
@@ -239,7 +239,7 @@ abstract class AbstractToken implements TokenInterface
      */
     public function getAttribute($name)
     {
-        if (!array_key_exists($name, $this->attributes)) {
+        if (!\array_key_exists($name, $this->attributes)) {
             throw new \InvalidArgumentException(sprintf('This token has no "%s" attribute.', $name));
         }
 
diff --git a/src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php b/src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php
index 058085e349..8509844f9a 100644
--- a/src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php
+++ b/src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php
@@ -42,7 +42,7 @@ class AccessDecisionManager implements AccessDecisionManagerInterface
     public function __construct(iterable $voters = [], string $strategy = self::STRATEGY_AFFIRMATIVE, bool $allowIfAllAbstainDecisions = false, bool $allowIfEqualGrantedDeniedDecisions = true)
     {
         $strategyMethod = 'decide'.ucfirst($strategy);
-        if (!\is_callable([$this, $strategyMethod])) {
+        if ('' === $strategy || !\is_callable([$this, $strategyMethod])) {
             throw new \InvalidArgumentException(sprintf('The strategy "%s" is not supported.', $strategy));
         }
 
diff --git a/src/Symfony/Component/Security/Core/Encoder/EncoderFactory.php b/src/Symfony/Component/Security/Core/Encoder/EncoderFactory.php
index a774d7e11c..8695ba3401 100644
--- a/src/Symfony/Component/Security/Core/Encoder/EncoderFactory.php
+++ b/src/Symfony/Component/Security/Core/Encoder/EncoderFactory.php
@@ -33,7 +33,7 @@ class EncoderFactory implements EncoderFactoryInterface
         $encoderKey = null;
 
         if ($user instanceof EncoderAwareInterface && (null !== $encoderName = $user->getEncoderName())) {
-            if (!array_key_exists($encoderName, $this->encoders)) {
+            if (!\array_key_exists($encoderName, $this->encoders)) {
                 throw new \RuntimeException(sprintf('The encoder "%s" was not configured.', $encoderName));
             }
 
diff --git a/src/Symfony/Component/Security/Http/Firewall/SimpleFormAuthenticationListener.php b/src/Symfony/Component/Security/Http/Firewall/SimpleFormAuthenticationListener.php
index f6fd0c1ec4..a8ccee0f7d 100644
--- a/src/Symfony/Component/Security/Http/Firewall/SimpleFormAuthenticationListener.php
+++ b/src/Symfony/Component/Security/Http/Firewall/SimpleFormAuthenticationListener.php
@@ -97,7 +97,7 @@ class SimpleFormAuthenticationListener extends AbstractAuthenticationListener
             $password = ParameterBagUtils::getRequestParameterValue($request, $this->options['password_parameter']);
         }
 
-        if (!\is_string($username) || (\is_object($username) && !\method_exists($username, '__toString'))) {
+        if (!\is_string($username) && (!\is_object($username) || !\method_exists($username, '__toString'))) {
             throw new BadRequestHttpException(sprintf('The key "%s" must be a string, "%s" given.', $this->options['username_parameter'], \gettype($username)));
         }
 
diff --git a/src/Symfony/Component/Security/Http/Firewall/UsernamePasswordFormAuthenticationListener.php b/src/Symfony/Component/Security/Http/Firewall/UsernamePasswordFormAuthenticationListener.php
index f6ce869b29..2b8ab8d09f 100644
--- a/src/Symfony/Component/Security/Http/Firewall/UsernamePasswordFormAuthenticationListener.php
+++ b/src/Symfony/Component/Security/Http/Firewall/UsernamePasswordFormAuthenticationListener.php
@@ -85,7 +85,7 @@ class UsernamePasswordFormAuthenticationListener extends AbstractAuthenticationL
             $password = ParameterBagUtils::getRequestParameterValue($request, $this->options['password_parameter']);
         }
 
-        if (!\is_string($username) || (\is_object($username) && !\method_exists($username, '__toString'))) {
+        if (!\is_string($username) && (!\is_object($username) || !\method_exists($username, '__toString'))) {
             throw new BadRequestHttpException(sprintf('The key "%s" must be a string, "%s" given.', $this->options['username_parameter'], \gettype($username)));
         }
 
diff --git a/src/Symfony/Component/Security/Http/Tests/Firewall/UsernamePasswordFormAuthenticationListenerTest.php b/src/Symfony/Component/Security/Http/Tests/Firewall/UsernamePasswordFormAuthenticationListenerTest.php
index 198ee6566d..f1536db6d2 100644
--- a/src/Symfony/Component/Security/Http/Tests/Firewall/UsernamePasswordFormAuthenticationListenerTest.php
+++ b/src/Symfony/Component/Security/Http/Tests/Firewall/UsernamePasswordFormAuthenticationListenerTest.php
@@ -81,7 +81,7 @@ class UsernamePasswordFormAuthenticationListenerTest extends TestCase
      * @expectedException \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
      * @expectedExceptionMessage The key "_username" must be a string, "array" given.
      */
-    public function testHandleNonStringUsername($postOnly)
+    public function testHandleNonStringUsernameWithArray($postOnly)
     {
         $request = Request::create('/login_check', 'POST', ['_username' => []]);
         $request->setSession($this->getMockBuilder('Symfony\Component\HttpFoundation\Session\SessionInterface')->getMock());
@@ -99,6 +99,79 @@ class UsernamePasswordFormAuthenticationListenerTest extends TestCase
         $listener->handle($event);
     }
 
+    /**
+     * @dataProvider postOnlyDataProvider
+     * @expectedException \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
+     * @expectedExceptionMessage The key "_username" must be a string, "integer" given.
+     */
+    public function testHandleNonStringUsernameWithInt($postOnly)
+    {
+        $request = Request::create('/login_check', 'POST', ['_username' => 42]);
+        $request->setSession($this->getMockBuilder('Symfony\Component\HttpFoundation\Session\SessionInterface')->getMock());
+        $listener = new UsernamePasswordFormAuthenticationListener(
+            new TokenStorage(),
+            $this->getMockBuilder('Symfony\Component\Security\Core\Authentication\AuthenticationManagerInterface')->getMock(),
+            new SessionAuthenticationStrategy(SessionAuthenticationStrategy::NONE),
+            $httpUtils = new HttpUtils(),
+            'foo',
+            new DefaultAuthenticationSuccessHandler($httpUtils),
+            new DefaultAuthenticationFailureHandler($this->getMockBuilder('Symfony\Component\HttpKernel\HttpKernelInterface')->getMock(), $httpUtils),
+            ['require_previous_session' => false, 'post_only' => $postOnly]
+        );
+        $event = new GetResponseEvent($this->getMockBuilder('Symfony\Component\HttpKernel\HttpKernelInterface')->getMock(), $request, HttpKernelInterface::MASTER_REQUEST);
+        $listener->handle($event);
+    }
+
+    /**
+     * @dataProvider postOnlyDataProvider
+     * @expectedException \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
+     * @expectedExceptionMessage The key "_username" must be a string, "object" given.
+     */
+    public function testHandleNonStringUsernameWithObject($postOnly)
+    {
+        $request = Request::create('/login_check', 'POST', ['_username' => new \stdClass()]);
+        $request->setSession($this->getMockBuilder('Symfony\Component\HttpFoundation\Session\SessionInterface')->getMock());
+        $listener = new UsernamePasswordFormAuthenticationListener(
+            new TokenStorage(),
+            $this->getMockBuilder('Symfony\Component\Security\Core\Authentication\AuthenticationManagerInterface')->getMock(),
+            new SessionAuthenticationStrategy(SessionAuthenticationStrategy::NONE),
+            $httpUtils = new HttpUtils(),
+            'foo',
+            new DefaultAuthenticationSuccessHandler($httpUtils),
+            new DefaultAuthenticationFailureHandler($this->getMockBuilder('Symfony\Component\HttpKernel\HttpKernelInterface')->getMock(), $httpUtils),
+            ['require_previous_session' => false, 'post_only' => $postOnly]
+        );
+        $event = new GetResponseEvent($this->getMockBuilder('Symfony\Component\HttpKernel\HttpKernelInterface')->getMock(), $request, HttpKernelInterface::MASTER_REQUEST);
+        $listener->handle($event);
+    }
+
+    /**
+     * @dataProvider postOnlyDataProvider
+     */
+    public function testHandleNonStringUsernameWith__toString($postOnly)
+    {
+        $usernameClass = $this->getMockBuilder(DummyUserClass::class)->getMock();
+        $usernameClass
+            ->expects($this->atLeastOnce())
+            ->method('__toString')
+            ->will($this->returnValue('someUsername'));
+
+        $request = Request::create('/login_check', 'POST', ['_username' => $usernameClass]);
+        $request->setSession($this->getMockBuilder('Symfony\Component\HttpFoundation\Session\SessionInterface')->getMock());
+        $listener = new UsernamePasswordFormAuthenticationListener(
+            new TokenStorage(),
+            $this->getMockBuilder('Symfony\Component\Security\Core\Authentication\AuthenticationManagerInterface')->getMock(),
+            new SessionAuthenticationStrategy(SessionAuthenticationStrategy::NONE),
+            $httpUtils = new HttpUtils(),
+            'foo',
+            new DefaultAuthenticationSuccessHandler($httpUtils),
+            new DefaultAuthenticationFailureHandler($this->getMockBuilder('Symfony\Component\HttpKernel\HttpKernelInterface')->getMock(), $httpUtils),
+            ['require_previous_session' => false, 'post_only' => $postOnly]
+        );
+        $event = new GetResponseEvent($this->getMockBuilder('Symfony\Component\HttpKernel\HttpKernelInterface')->getMock(), $request, HttpKernelInterface::MASTER_REQUEST);
+        $listener->handle($event);
+    }
+
     public function postOnlyDataProvider()
     {
         return [
@@ -115,3 +188,11 @@ class UsernamePasswordFormAuthenticationListenerTest extends TestCase
         ];
     }
 }
+
+class DummyUserClass
+{
+    public function __toString()
+    {
+        return '';
+    }
+}
diff --git a/src/Symfony/Component/Serializer/Mapping/ClassDiscriminatorFromClassMetadata.php b/src/Symfony/Component/Serializer/Mapping/ClassDiscriminatorFromClassMetadata.php
index 1178f03cfb..23554ffda9 100644
--- a/src/Symfony/Component/Serializer/Mapping/ClassDiscriminatorFromClassMetadata.php
+++ b/src/Symfony/Component/Serializer/Mapping/ClassDiscriminatorFromClassMetadata.php
@@ -55,7 +55,7 @@ class ClassDiscriminatorFromClassMetadata implements ClassDiscriminatorResolverI
         }
 
         $cacheKey = \is_object($object) ? \get_class($object) : $object;
-        if (!array_key_exists($cacheKey, $this->mappingForMappedObjectCache)) {
+        if (!\array_key_exists($cacheKey, $this->mappingForMappedObjectCache)) {
             $this->mappingForMappedObjectCache[$cacheKey] = $this->resolveMappingForMappedObject($object);
         }
 
diff --git a/src/Symfony/Component/Serializer/Normalizer/AbstractNormalizer.php b/src/Symfony/Component/Serializer/Normalizer/AbstractNormalizer.php
index 300c7f1b3c..e1f5d136dd 100644
--- a/src/Symfony/Component/Serializer/Normalizer/AbstractNormalizer.php
+++ b/src/Symfony/Component/Serializer/Normalizer/AbstractNormalizer.php
@@ -398,14 +398,14 @@ abstract class AbstractNormalizer implements NormalizerInterface, DenormalizerIn
                 $allowed = false === $allowedAttributes || \in_array($paramName, $allowedAttributes);
                 $ignored = !$this->isAllowedAttribute($class, $paramName, $format, $context);
                 if ($constructorParameter->isVariadic()) {
-                    if ($allowed && !$ignored && (isset($data[$key]) || array_key_exists($key, $data))) {
+                    if ($allowed && !$ignored && (isset($data[$key]) || \array_key_exists($key, $data))) {
                         if (!\is_array($data[$paramName])) {
                             throw new RuntimeException(sprintf('Cannot create an instance of %s from serialized data because the variadic parameter %s can only accept an array.', $class, $constructorParameter->name));
                         }
 
                         $params = array_merge($params, $data[$paramName]);
                     }
-                } elseif ($allowed && !$ignored && (isset($data[$key]) || array_key_exists($key, $data))) {
+                } elseif ($allowed && !$ignored && (isset($data[$key]) || \array_key_exists($key, $data))) {
                     $parameterData = $data[$key];
                     if (null === $parameterData && $constructorParameter->allowsNull()) {
                         $params[] = null;
@@ -417,9 +417,9 @@ abstract class AbstractNormalizer implements NormalizerInterface, DenormalizerIn
                     // Don't run set for a parameter passed to the constructor
                     $params[] = $this->denormalizeParameter($reflectionClass, $constructorParameter, $paramName, $parameterData, $context, $format);
                     unset($data[$key]);
-                } elseif (array_key_exists($key, $context[static::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class] ?? [])) {
+                } elseif (\array_key_exists($key, $context[static::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class] ?? [])) {
                     $params[] = $context[static::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class][$key];
-                } elseif (array_key_exists($key, $this->defaultContext[self::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class] ?? [])) {
+                } elseif (\array_key_exists($key, $this->defaultContext[self::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class] ?? [])) {
                     $params[] = $this->defaultContext[self::DEFAULT_CONSTRUCTOR_ARGUMENTS][$class][$key];
                 } elseif ($constructorParameter->isDefaultValueAvailable()) {
                     $params[] = $constructorParameter->getDefaultValue();
diff --git a/src/Symfony/Component/Serializer/Normalizer/DateTimeNormalizer.php b/src/Symfony/Component/Serializer/Normalizer/DateTimeNormalizer.php
index d3de806e18..51ad59a7e7 100644
--- a/src/Symfony/Component/Serializer/Normalizer/DateTimeNormalizer.php
+++ b/src/Symfony/Component/Serializer/Normalizer/DateTimeNormalizer.php
@@ -157,6 +157,7 @@ class DateTimeNormalizer implements NormalizerInterface, DenormalizerInterface,
     private function getTimezone(array $context)
     {
         $dateTimeZone = $context[self::TIMEZONE_KEY] ?? $this->defaultContext[self::TIMEZONE_KEY];
+
         if (null === $dateTimeZone) {
             return null;
         }
diff --git a/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php b/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php
index 530f168c6a..94ed6d8b63 100644
--- a/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php
+++ b/src/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php
@@ -113,7 +113,7 @@ class ObjectNormalizer extends AbstractObjectNormalizer
     protected function getAttributeValue($object, $attribute, $format = null, array $context = [])
     {
         $cacheKey = \get_class($object);
-        if (!array_key_exists($cacheKey, $this->discriminatorCache)) {
+        if (!\array_key_exists($cacheKey, $this->discriminatorCache)) {
             $this->discriminatorCache[$cacheKey] = null;
             if (null !== $this->classDiscriminatorResolver) {
                 $mapping = $this->classDiscriminatorResolver->getMappingForMappedObject($object);
diff --git a/src/Symfony/Component/Templating/TemplateReference.php b/src/Symfony/Component/Templating/TemplateReference.php
index 18c6bda2df..ddff4db857 100644
--- a/src/Symfony/Component/Templating/TemplateReference.php
+++ b/src/Symfony/Component/Templating/TemplateReference.php
@@ -41,7 +41,7 @@ class TemplateReference implements TemplateReferenceInterface
      */
     public function set($name, $value)
     {
-        if (array_key_exists($name, $this->parameters)) {
+        if (\array_key_exists($name, $this->parameters)) {
             $this->parameters[$name] = $value;
         } else {
             throw new \InvalidArgumentException(sprintf('The template does not support the "%s" parameter.', $name));
@@ -55,7 +55,7 @@ class TemplateReference implements TemplateReferenceInterface
      */
     public function get($name)
     {
-        if (array_key_exists($name, $this->parameters)) {
+        if (\array_key_exists($name, $this->parameters)) {
             return $this->parameters[$name];
         }
 
diff --git a/src/Symfony/Component/Translation/Dumper/FileDumper.php b/src/Symfony/Component/Translation/Dumper/FileDumper.php
index 57ce9d2141..8457ecc7ec 100644
--- a/src/Symfony/Component/Translation/Dumper/FileDumper.php
+++ b/src/Symfony/Component/Translation/Dumper/FileDumper.php
@@ -63,7 +63,7 @@ abstract class FileDumper implements DumperInterface
      */
     public function dump(MessageCatalogue $messages, $options = [])
     {
-        if (!array_key_exists('path', $options)) {
+        if (!\array_key_exists('path', $options)) {
             throw new InvalidArgumentException('The file dumper needs a path option.');
         }
 
diff --git a/src/Symfony/Component/Translation/Dumper/XliffFileDumper.php b/src/Symfony/Component/Translation/Dumper/XliffFileDumper.php
index 2718da010d..8d2694f24e 100644
--- a/src/Symfony/Component/Translation/Dumper/XliffFileDumper.php
+++ b/src/Symfony/Component/Translation/Dumper/XliffFileDumper.php
@@ -27,11 +27,11 @@ class XliffFileDumper extends FileDumper
     public function formatCatalogue(MessageCatalogue $messages, $domain, array $options = [])
     {
         $xliffVersion = '1.2';
-        if (array_key_exists('xliff_version', $options)) {
+        if (\array_key_exists('xliff_version', $options)) {
             $xliffVersion = $options['xliff_version'];
         }
 
-        if (array_key_exists('default_locale', $options)) {
+        if (\array_key_exists('default_locale', $options)) {
             $defaultLocale = $options['default_locale'];
         } else {
             $defaultLocale = \Locale::getDefault();
@@ -58,7 +58,7 @@ class XliffFileDumper extends FileDumper
     private function dumpXliff1($defaultLocale, MessageCatalogue $messages, $domain, array $options = [])
     {
         $toolInfo = ['tool-id' => 'symfony', 'tool-name' => 'Symfony'];
-        if (array_key_exists('tool_info', $options)) {
+        if (\array_key_exists('tool_info', $options)) {
             $toolInfo = array_merge($toolInfo, $options['tool_info']);
         }
 
@@ -204,6 +204,6 @@ class XliffFileDumper extends FileDumper
      */
     private function hasMetadataArrayInfo($key, $metadata = null)
     {
-        return null !== $metadata && array_key_exists($key, $metadata) && ($metadata[$key] instanceof \Traversable || \is_array($metadata[$key]));
+        return null !== $metadata && \array_key_exists($key, $metadata) && ($metadata[$key] instanceof \Traversable || \is_array($metadata[$key]));
     }
 }
diff --git a/src/Symfony/Component/Validator/Constraint.php b/src/Symfony/Component/Validator/Constraint.php
index ae27ba2163..b1a5e0c1a2 100644
--- a/src/Symfony/Component/Validator/Constraint.php
+++ b/src/Symfony/Component/Validator/Constraint.php
@@ -122,7 +122,7 @@ abstract class Constraint
         }
         if ($options && \is_array($options) && \is_string(key($options))) {
             foreach ($options as $option => $value) {
-                if (array_key_exists($option, $knownOptions)) {
+                if (\array_key_exists($option, $knownOptions)) {
                     $this->$option = $value;
                     unset($missingOptions[$option]);
                 } else {
@@ -136,7 +136,7 @@ abstract class Constraint
                 throw new ConstraintDefinitionException(sprintf('No default option is configured for constraint %s', \get_class($this)));
             }
 
-            if (array_key_exists($option, $knownOptions)) {
+            if (\array_key_exists($option, $knownOptions)) {
                 $this->$option = $options;
                 unset($missingOptions[$option]);
             } else {
diff --git a/src/Symfony/Component/Validator/Constraints/CollectionValidator.php b/src/Symfony/Component/Validator/Constraints/CollectionValidator.php
index 731501e08d..cbc3e198a3 100644
--- a/src/Symfony/Component/Validator/Constraints/CollectionValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/CollectionValidator.php
@@ -51,7 +51,7 @@ class CollectionValidator extends ConstraintValidator
 
         foreach ($constraint->fields as $field => $fieldConstraint) {
             // bug fix issue #2779
-            $existsInArray = \is_array($value) && array_key_exists($field, $value);
+            $existsInArray = \is_array($value) && \array_key_exists($field, $value);
             $existsInArrayAccess = $value instanceof \ArrayAccess && $value->offsetExists($field);
 
             if ($existsInArray || $existsInArrayAccess) {
diff --git a/src/Symfony/Component/Validator/Constraints/Email.php b/src/Symfony/Component/Validator/Constraints/Email.php
index 7d13eceaf7..c6c760c2c0 100644
--- a/src/Symfony/Component/Validator/Constraints/Email.php
+++ b/src/Symfony/Component/Validator/Constraints/Email.php
@@ -76,19 +76,19 @@ class Email extends Constraint
 
     public function __construct($options = null)
     {
-        if (\is_array($options) && array_key_exists('strict', $options)) {
+        if (\is_array($options) && \array_key_exists('strict', $options)) {
             @trigger_error(sprintf('The "strict" property is deprecated since Symfony 4.1. Use "mode"=>"%s" instead.', self::VALIDATION_MODE_STRICT), E_USER_DEPRECATED);
         }
 
-        if (\is_array($options) && array_key_exists('checkMX', $options)) {
+        if (\is_array($options) && \array_key_exists('checkMX', $options)) {
             @trigger_error('The "checkMX" option is deprecated since Symfony 4.2.', E_USER_DEPRECATED);
         }
 
-        if (\is_array($options) && array_key_exists('checkHost', $options)) {
+        if (\is_array($options) && \array_key_exists('checkHost', $options)) {
             @trigger_error('The "checkHost" option is deprecated since Symfony 4.2.', E_USER_DEPRECATED);
         }
 
-        if (\is_array($options) && array_key_exists('mode', $options) && !\in_array($options['mode'], self::$validationModes, true)) {
+        if (\is_array($options) && \array_key_exists('mode', $options) && !\in_array($options['mode'], self::$validationModes, true)) {
             throw new \InvalidArgumentException('The "mode" parameter value is not valid.');
         }
 
diff --git a/src/Symfony/Component/Validator/Constraints/IbanValidator.php b/src/Symfony/Component/Validator/Constraints/IbanValidator.php
index d6530ab101..e927f013aa 100644
--- a/src/Symfony/Component/Validator/Constraints/IbanValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/IbanValidator.php
@@ -182,7 +182,7 @@ class IbanValidator extends ConstraintValidator
         }
 
         // ...have a format available
-        if (!array_key_exists($countryCode, self::$formats)) {
+        if (!\array_key_exists($countryCode, self::$formats)) {
             $this->context->buildViolation($constraint->message)
                 ->setParameter('{{ value }}', $this->formatValue($value))
                 ->setCode(Iban::NOT_SUPPORTED_COUNTRY_CODE_ERROR)
diff --git a/src/Symfony/Component/Validator/Constraints/LessThanOrEqual.php b/src/Symfony/Component/Validator/Constraints/LessThanOrEqual.php
index 74f7aeb8fa..806ca4990f 100644
--- a/src/Symfony/Component/Validator/Constraints/LessThanOrEqual.php
+++ b/src/Symfony/Component/Validator/Constraints/LessThanOrEqual.php
@@ -20,7 +20,7 @@ namespace Symfony\Component\Validator\Constraints;
  */
 class LessThanOrEqual extends AbstractComparison
 {
-    const TOO_HIGH_ERROR = '079d7420-2d13-460c-8756-de810eeb37d2';
+    const TOO_HIGH_ERROR = '30fbb013-d015-4232-8b3b-8f3be97a7e14';
 
     protected static $errorNames = [
         self::TOO_HIGH_ERROR => 'TOO_HIGH_ERROR',
diff --git a/src/Symfony/Component/Validator/Constraints/Regex.php b/src/Symfony/Component/Validator/Constraints/Regex.php
index a71e4de259..dc9e5ea885 100644
--- a/src/Symfony/Component/Validator/Constraints/Regex.php
+++ b/src/Symfony/Component/Validator/Constraints/Regex.php
@@ -79,7 +79,7 @@ class Regex extends Constraint
         // Unescape the delimiter
         $pattern = str_replace('\\'.$delimiter, $delimiter, substr($this->pattern, 1, -1));
 
-        // If the pattern is inverted, we can simply wrap it in
+        // If the pattern is inverted, we can wrap it in
         // ((?!pattern).)*
         if (!$this->match) {
             return '((?!'.$pattern.').)*';
diff --git a/src/Symfony/Component/Validator/Constraints/Traverse.php b/src/Symfony/Component/Validator/Constraints/Traverse.php
index 4572c9b219..78d115fdbb 100644
--- a/src/Symfony/Component/Validator/Constraints/Traverse.php
+++ b/src/Symfony/Component/Validator/Constraints/Traverse.php
@@ -25,7 +25,7 @@ class Traverse extends Constraint
 
     public function __construct($options = null)
     {
-        if (\is_array($options) && array_key_exists('groups', $options)) {
+        if (\is_array($options) && \array_key_exists('groups', $options)) {
             throw new ConstraintDefinitionException(sprintf('The option "groups" is not supported by the constraint %s', __CLASS__));
         }
 
diff --git a/src/Symfony/Component/Validator/Constraints/Url.php b/src/Symfony/Component/Validator/Constraints/Url.php
index 2a237bffad..815d73be7c 100644
--- a/src/Symfony/Component/Validator/Constraints/Url.php
+++ b/src/Symfony/Component/Validator/Constraints/Url.php
@@ -109,10 +109,10 @@ class Url extends Constraint
     public function __construct($options = null)
     {
         if (\is_array($options)) {
-            if (array_key_exists('checkDNS', $options)) {
+            if (\array_key_exists('checkDNS', $options)) {
                 @trigger_error(sprintf('The "checkDNS" option in "%s" is deprecated since Symfony 4.1. Its false-positive rate is too high to be relied upon.', self::class), E_USER_DEPRECATED);
             }
-            if (array_key_exists('dnsMessage', $options)) {
+            if (\array_key_exists('dnsMessage', $options)) {
                 @trigger_error(sprintf('The "dnsMessage" option in "%s" is deprecated since Symfony 4.1.', self::class), E_USER_DEPRECATED);
             }
         }
diff --git a/src/Symfony/Component/Validator/Mapping/ClassMetadata.php b/src/Symfony/Component/Validator/Mapping/ClassMetadata.php
index afbe72b735..6e0256c290 100644
--- a/src/Symfony/Component/Validator/Mapping/ClassMetadata.php
+++ b/src/Symfony/Component/Validator/Mapping/ClassMetadata.php
@@ -366,7 +366,7 @@ class ClassMetadata extends GenericMetadata implements ClassMetadataInterface
      */
     public function hasPropertyMetadata($property)
     {
-        return array_key_exists($property, $this->members);
+        return \array_key_exists($property, $this->members);
     }
 
     /**
diff --git a/src/Symfony/Component/Validator/Mapping/ClassMetadataInterface.php b/src/Symfony/Component/Validator/Mapping/ClassMetadataInterface.php
index e48e241ab8..1b6f07ac8e 100644
--- a/src/Symfony/Component/Validator/Mapping/ClassMetadataInterface.php
+++ b/src/Symfony/Component/Validator/Mapping/ClassMetadataInterface.php
@@ -86,8 +86,8 @@ interface ClassMetadataInterface extends MetadataInterface
     /**
      * Returns all metadata instances for the given named property.
      *
-     * If your implementation does not support properties, simply throw an
-     * exception in this method (for example a <tt>BadMethodCallException</tt>).
+     * If your implementation does not support properties, throw an exception
+     * in this method (for example a <tt>BadMethodCallException</tt>).
      *
      * @param string $property The property name
      *
diff --git a/src/Symfony/Component/Validator/Resources/translations/validators.af.xlf b/src/Symfony/Component/Validator/Resources/translations/validators.af.xlf
index 177bb0038f..731e64aa7f 100644
--- a/src/Symfony/Component/Validator/Resources/translations/validators.af.xlf
+++ b/src/Symfony/Component/Validator/Resources/translations/validators.af.xlf
@@ -222,6 +222,118 @@
                 <source>Unsupported card type or invalid card number.</source>
                 <target>Nie-ondersteunde tipe kaart of ongeldige kredietkaart nommer.</target>
             </trans-unit>
+            <trans-unit id="59">
+                <source>This is not a valid International Bank Account Number (IBAN).</source>
+                <target>Hierdie is nie 'n geldige Internationale Bank Rekening Nommer (IBAN) nie.</target>
+            </trans-unit>
+            <trans-unit id="60">
+                <source>This value is not a valid ISBN-10.</source>
+                <target>Hierdie waarde is nie 'n geldige ISBN-10 nie.</target>
+            </trans-unit>
+            <trans-unit id="61">
+                <source>This value is not a valid ISBN-13.</source>
+                <target>Hierdie waarde is nie 'n geldige ISBN-13 nie.</target>
+            </trans-unit>
+            <trans-unit id="62">
+                <source>This value is neither a valid ISBN-10 nor a valid ISBN-13.</source>
+                <target>Hierdie waarde is nie 'n geldige ISBN-10 of ISBN-13 nie.</target>
+            </trans-unit>
+            <trans-unit id="63">
+                <source>This value is not a valid ISSN.</source>
+                <target>Hierdie waarde is nie 'n geldige ISSN nie.</target>
+            </trans-unit>
+            <trans-unit id="64">
+                <source>This value is not a valid currency.</source>
+                <target>Hierdie waarde is nie 'n geldige geldeenheid nie.</target>
+            </trans-unit>
+            <trans-unit id="65">
+                <source>This value should be equal to {{ compared_value }}.</source>
+                <target>Hierdie waarde moet gelyk aan {{ compared_value }} wees.</target>
+            </trans-unit>
+            <trans-unit id="66">
+                <source>This value should be greater than {{ compared_value }}.</source>
+                <target>Hierdie waarde moet meer as {{ compared_value }} wees.</target>
+            </trans-unit>
+            <trans-unit id="67">
+                <source>This value should be greater than or equal to {{ compared_value }}.</source>
+                <target>Hierdie waarde moet meer of gelyk aan {{ compared_value }} wees.</target>
+            </trans-unit>
+            <trans-unit id="68">
+                <source>This value should be identical to {{ compared_value_type }} {{ compared_value }}.</source>
+                <target>Hierdie waarde moet identies aan {{ compared_value_type }} {{ compared_value }} wees.</target>
+            </trans-unit>
+            <trans-unit id="69">
+                <source>This value should be less than {{ compared_value }}.</source>
+                <target>Hierdie waarde moet minder as {{ compared_value }} wees.</target>
+            </trans-unit>
+            <trans-unit id="70">
+                <source>This value should be less than or equal to {{ compared_value }}.</source>
+                <target>Hierdie waarde moet minder of gelyk aan {{ compared_value }} wees.</target>
+            </trans-unit>
+            <trans-unit id="71">
+                <source>This value should not be equal to {{ compared_value }}.</source>
+                <target>Hierdie waarde moet nie dieselfde as {{ compared_value }} wees nie.</target>
+            </trans-unit>
+            <trans-unit id="72">
+                <source>This value should not be identical to {{ compared_value_type }} {{ compared_value }}.</source>
+                <target>Hierdie waarde moet nie identies as {{ compared_value_type }} {{ compared_value }} wees nie.</target>
+            </trans-unit>
+            <trans-unit id="73">
+                <source>The image ratio is too big ({{ ratio }}). Allowed maximum ratio is {{ max_ratio }}.</source>
+                <target>Die beeld aspek is te groot ({{ ratio }}). Die maksimum toegelate aspek is {{ max_ratio }}.</target>
+            </trans-unit>
+            <trans-unit id="74">
+                <source>The image ratio is too small ({{ ratio }}). Minimum ratio expected is {{ min_ratio }}.</source>
+                <target>Die beeld aspek is te klein ({{ ratio }}). Die minimum toegelate aspek is {{ min_ratio }}.</target>
+            </trans-unit>
+            <trans-unit id="75">
+                <source>The image is square ({{ width }}x{{ height }}px). Square images are not allowed.</source>
+                <target>Die beeld is vierkantig ({{ width }}x{{ height }}px). Vierkantige beelde word nie toegelaat nie.</target>
+            </trans-unit>
+            <trans-unit id="76">
+                <source>The image is landscape oriented ({{ width }}x{{ height }}px). Landscape oriented images are not allowed.</source>
+                <target>Die beeld is landskap georiënteerd ({{ width }}x{{ height }}px). Landskap georiënteerde beelde word nie toegelaat nie.</target>
+            </trans-unit>
+            <trans-unit id="77">
+                <source>The image is portrait oriented ({{ width }}x{{ height }}px). Portrait oriented images are not allowed.</source>
+                <target>Die beeld dis portret georiënteerd ({{ width }}x{{ height }}px). Portret georiënteerde beelde word nie toegelaat nie.</target>
+            </trans-unit>
+            <trans-unit id="78">
+                <source>An empty file is not allowed.</source>
+                <target>'n Leë lêer word nie toegelaat nie.</target>
+            </trans-unit>
+            <trans-unit id="79">
+                <source>The host could not be resolved.</source>
+                <target>Die gasheer kon nie opgelos word nie.</target>
+            </trans-unit>
+            <trans-unit id="80">
+                <source>This value does not match the expected {{ charset }} charset.</source>
+                <target>Die waarde stem nie ooreen met die verwagte {{ charset }} karakterstel nie.</target>
+            </trans-unit>
+            <trans-unit id="81">
+                <source>This is not a valid Business Identifier Code (BIC).</source>
+                <target>Hierdie is nie 'n geldige Besigheids Identifikasie Kode (BIC) nie.</target>
+            </trans-unit>
+            <trans-unit id="82">
+                <source>Error</source>
+                <target>Fout</target>
+            </trans-unit>
+            <trans-unit id="83">
+                <source>This is not a valid UUID.</source>
+                <target>Hierdie is nie 'n geldige UUID nie.</target>
+            </trans-unit>
+            <trans-unit id="84">
+                <source>This value should be a multiple of {{ compared_value }}.</source>
+                <target>Hierdie waarde moet 'n veelvoud van {{ compared_value }} wees.</target>
+            </trans-unit>
+            <trans-unit id="85">
+                <source>This Business Identifier Code (BIC) is not associated with IBAN {{ iban }}.</source>
+                <target>Hierdie Besigheids Identifikasie Kode (BIK) is nie geassosieer met IBAN {{ iban }} nie.</target>
+            </trans-unit>
+            <trans-unit id="86">
+                <source>This value should be valid JSON.</source>
+                <target>Hierdie waarde moet geldige JSON wees.</target>
+            </trans-unit>
         </body>
     </file>
 </xliff>
diff --git a/src/Symfony/Component/Validator/Resources/translations/validators.el.xlf b/src/Symfony/Component/Validator/Resources/translations/validators.el.xlf
index a3199bcc9d..3b9bbef66e 100644
--- a/src/Symfony/Component/Validator/Resources/translations/validators.el.xlf
+++ b/src/Symfony/Component/Validator/Resources/translations/validators.el.xlf
@@ -278,6 +278,58 @@
                 <source>This value should not be identical to {{ compared_value_type }} {{ compared_value }}.</source>
                 <target>Αυτή η τιμή δεν πρέπει να είναι πανομοιότυπη με {{ compared_value_type }} {{ compared_value }}.</target>
             </trans-unit>
+            <trans-unit id="73">
+                <source>The image ratio is too big ({{ ratio }}). Allowed maximum ratio is {{ max_ratio }}.</source>
+                <target>Η αναλογία πλάτους-ύψους της εικόνας είναι πολύ μεγάλη ({{ ratio }}). Μέγιστη επιτρεπτή αναλογία {{ max_ratio }}.</target>
+            </trans-unit>
+            <trans-unit id="74">
+                <source>The image ratio is too small ({{ ratio }}). Minimum ratio expected is {{ min_ratio }}.</source>
+                <target>Η αναλογία πλάτους-ύψους της εικόνας είναι πολύ μικρή ({{ ratio }}). Ελάχιστη επιτρεπτή αναλογία {{ min_ratio }}.</target>
+            </trans-unit>
+            <trans-unit id="75">
+                <source>The image is square ({{ width }}x{{ height }}px). Square images are not allowed.</source>
+                <target>Η εικόνα είναι τετράγωνη ({{ width }}x{{ height }}px). Δεν επιτρέπονται τετράγωνες εικόνες.</target>
+            </trans-unit>
+            <trans-unit id="76">
+                <source>The image is landscape oriented ({{ width }}x{{ height }}px). Landscape oriented images are not allowed.</source>
+                <target>Η εικόνα έχει οριζόντιο προσανατολισμό ({{ width }}x{{ height }}px). Δεν επιτρέπονται εικόνες με οριζόντιο προσανατολισμό.</target>
+            </trans-unit>
+            <trans-unit id="77">
+                <source>The image is portrait oriented ({{ width }}x{{ height }}px). Portrait oriented images are not allowed.</source>
+                <target>Η εικόνα έχει κάθετο προσανατολισμό ({{ width }}x{{ height }}px). Δεν επιτρέπονται εικόνες με κάθετο προσανατολισμό.</target>
+            </trans-unit>
+            <trans-unit id="78">
+                <source>An empty file is not allowed.</source>
+                <target>Δεν επιτρέπεται κενό αρχείο.</target>
+            </trans-unit>
+            <trans-unit id="79">
+                <source>The host could not be resolved.</source>
+                <target>Η διεύθυνση δεν μπόρεσε να επιλυθεί.</target>
+            </trans-unit>
+            <trans-unit id="80">
+                <source>This value does not match the expected {{ charset }} charset.</source>
+                <target>Αυτή η τιμή δεν ταιριάζει στο αναμενόμενο {{ charset }} σύνολο χαρακτήρων.</target>
+            </trans-unit>
+            <trans-unit id="81">
+                <source>This is not a valid Business Identifier Code (BIC).</source>
+                <target>Αυτός δεν έιναι ένας έγκυρος κωδικός BIC.</target>
+            </trans-unit>
+            <trans-unit id="82">
+                <source>Error</source>
+                <target>Σφάλμα</target>
+            </trans-unit>
+            <trans-unit id="83">
+                <source>This is not a valid UUID.</source>
+                <target>Αυτό δεν είναι ένα έγκυρο UUID.</target>
+            </trans-unit>
+            <trans-unit id="84">
+                <source>This value should be a multiple of {{ compared_value }}.</source>
+                <target>Αυτή η τιμή θα έπρεπε να είναι πολλαπλάσιο του {{ compared_value }}.</target>
+            </trans-unit>
+            <trans-unit id="85">
+                <source>This Business Identifier Code (BIC) is not associated with IBAN {{ iban }}.</source>
+                <target>Αυτός ο κωδικός BIC δεν σχετίζεται με το IBAN {{ iban }}.</target>
+            </trans-unit>
         </body>
     </file>
 </xliff>
diff --git a/src/Symfony/Component/Validator/Resources/translations/validators.hr.xlf b/src/Symfony/Component/Validator/Resources/translations/validators.hr.xlf
index 126ef90332..ab033a11c3 100644
--- a/src/Symfony/Component/Validator/Resources/translations/validators.hr.xlf
+++ b/src/Symfony/Component/Validator/Resources/translations/validators.hr.xlf
@@ -318,6 +318,22 @@
                 <source>Error</source>
                 <target>Greška</target>
             </trans-unit>
+            <trans-unit id="83">
+                <source>This is not a valid UUID.</source>
+                <target>Ovo nije validan UUID.</target>
+            </trans-unit>
+            <trans-unit id="84">
+                <source>This value should be a multiple of {{ compared_value }}.</source>
+                <target>Ova vrijednost treba biti višekratnik od {{ compared_value }}.</target>
+            </trans-unit>
+            <trans-unit id="85">
+                <source>This Business Identifier Code (BIC) is not associated with IBAN {{ iban }}.</source>
+                <target>Poslovni identifikacijski broj (BIC) nije povezan sa IBAN brojem {{ iban }}.</target>
+            </trans-unit>
+            <trans-unit id="86">
+                <source>This value should be valid JSON.</source>
+                <target>Ova vrijednost treba biti validan JSON.</target>
+            </trans-unit>
         </body>
     </file>
 </xliff>
diff --git a/src/Symfony/Component/Validator/Resources/translations/validators.pt_BR.xlf b/src/Symfony/Component/Validator/Resources/translations/validators.pt_BR.xlf
index b617062318..8616edf4b9 100644
--- a/src/Symfony/Component/Validator/Resources/translations/validators.pt_BR.xlf
+++ b/src/Symfony/Component/Validator/Resources/translations/validators.pt_BR.xlf
@@ -314,6 +314,26 @@
                 <source>This is not a valid Business Identifier Code (BIC).</source>
                 <target>Este não é um Código Identificador Bancário (BIC) válido.</target>
             </trans-unit>
+            <trans-unit id="82">
+                <source>Error</source>
+                <target>Erro</target>
+            </trans-unit>
+            <trans-unit id="83">
+                <source>This is not a valid UUID.</source>
+                <target>Este não é um UUID válido.</target>
+            </trans-unit>
+            <trans-unit id="84">
+                <source>This value should be a multiple of {{ compared_value }}.</source>
+                <target>Este valor deve ser múltiplo de {{ compared_value }}.</target>
+            </trans-unit>
+            <trans-unit id="85">
+                <source>This Business Identifier Code (BIC) is not associated with IBAN {{ iban }}.</source>
+                <target>Este Código Identificador Bancário (BIC) não está associado ao IBAN {{ iban }}.</target>
+            </trans-unit>
+            <trans-unit id="86">
+                <source>This value should be valid JSON.</source>
+                <target>Este valor deve ser um JSON válido.</target>
+            </trans-unit>
         </body>
     </file>
 </xliff>
diff --git a/src/Symfony/Component/Validator/Tests/Fixtures/CustomArrayObject.php b/src/Symfony/Component/Validator/Tests/Fixtures/CustomArrayObject.php
index ac48a512c6..1edf1de081 100644
--- a/src/Symfony/Component/Validator/Tests/Fixtures/CustomArrayObject.php
+++ b/src/Symfony/Component/Validator/Tests/Fixtures/CustomArrayObject.php
@@ -26,7 +26,7 @@ class CustomArrayObject implements \ArrayAccess, \IteratorAggregate, \Countable,
 
     public function offsetExists($offset)
     {
-        return array_key_exists($offset, $this->array);
+        return \array_key_exists($offset, $this->array);
     }
 
     public function offsetGet($offset)
diff --git a/src/Symfony/Component/VarDumper/Caster/DoctrineCaster.php b/src/Symfony/Component/VarDumper/Caster/DoctrineCaster.php
index 6adf9dd837..696b87816e 100644
--- a/src/Symfony/Component/VarDumper/Caster/DoctrineCaster.php
+++ b/src/Symfony/Component/VarDumper/Caster/DoctrineCaster.php
@@ -26,7 +26,7 @@ class DoctrineCaster
     public static function castCommonProxy(CommonProxy $proxy, array $a, Stub $stub, $isNested)
     {
         foreach (['__cloner__', '__initializer__'] as $k) {
-            if (array_key_exists($k, $a)) {
+            if (\array_key_exists($k, $a)) {
                 unset($a[$k]);
                 ++$stub->cut;
             }
@@ -38,7 +38,7 @@ class DoctrineCaster
     public static function castOrmProxy(OrmProxy $proxy, array $a, Stub $stub, $isNested)
     {
         foreach (['_entityPersister', '_identifier'] as $k) {
-            if (array_key_exists($k = "\0Doctrine\\ORM\\Proxy\\Proxy\0".$k, $a)) {
+            if (\array_key_exists($k = "\0Doctrine\\ORM\\Proxy\\Proxy\0".$k, $a)) {
                 unset($a[$k]);
                 ++$stub->cut;
             }
@@ -50,7 +50,7 @@ class DoctrineCaster
     public static function castPersistentCollection(PersistentCollection $coll, array $a, Stub $stub, $isNested)
     {
         foreach (['snapshot', 'association', 'typeClass'] as $k) {
-            if (array_key_exists($k = "\0Doctrine\\ORM\\PersistentCollection\0".$k, $a)) {
+            if (\array_key_exists($k = "\0Doctrine\\ORM\\PersistentCollection\0".$k, $a)) {
                 $a[$k] = new CutStub($a[$k]);
             }
         }
diff --git a/src/Symfony/Component/VarDumper/Cloner/Data.php b/src/Symfony/Component/VarDumper/Cloner/Data.php
index 92a6f41cdd..838aeb0c6a 100644
--- a/src/Symfony/Component/VarDumper/Cloner/Data.php
+++ b/src/Symfony/Component/VarDumper/Cloner/Data.php
@@ -245,7 +245,7 @@ class Data implements \ArrayAccess, \Countable, \IteratorAggregate
         $children = $this->data[$item->position];
 
         foreach ($keys as $key) {
-            if (isset($children[$key]) || array_key_exists($key, $children)) {
+            if (isset($children[$key]) || \array_key_exists($key, $children)) {
                 $data = clone $this;
                 $data->key = $key;
                 $data->position = $item->position;
diff --git a/src/Symfony/Component/VarDumper/Cloner/VarCloner.php b/src/Symfony/Component/VarDumper/Cloner/VarCloner.php
index a50adef9f5..b8318c514f 100644
--- a/src/Symfony/Component/VarDumper/Cloner/VarCloner.php
+++ b/src/Symfony/Component/VarDumper/Cloner/VarCloner.php
@@ -31,6 +31,7 @@ class VarCloner extends AbstractCloner
         $indexedArrays = [];       // Map of queue indexes that hold numerically indexed arrays
         $hardRefs = [];            // Map of original zval ids to stub objects
         $objRefs = [];             // Map of original object handles to their stub object counterpart
+        $objects = [];             // Keep a ref to objects to ensure their handle cannot be reused while cloning
         $resRefs = [];             // Map of original resource handles to their stub object counterpart
         $values = [];              // Map of stub objects' ids to original values
         $maxItems = $this->maxItems;
@@ -193,6 +194,7 @@ class VarCloner extends AbstractCloner
                         }
                         if (empty($objRefs[$h])) {
                             $objRefs[$h] = $stub;
+                            $objects[] = $v;
                         } else {
                             $stub = $objRefs[$h];
                             ++$stub->refCount;
diff --git a/src/Symfony/Component/Workflow/DependencyInjection/ValidateWorkflowsPass.php b/src/Symfony/Component/Workflow/DependencyInjection/ValidateWorkflowsPass.php
index b4e222d335..175a1f5b96 100644
--- a/src/Symfony/Component/Workflow/DependencyInjection/ValidateWorkflowsPass.php
+++ b/src/Symfony/Component/Workflow/DependencyInjection/ValidateWorkflowsPass.php
@@ -34,13 +34,13 @@ class ValidateWorkflowsPass implements CompilerPassInterface
         $taggedServices = $container->findTaggedServiceIds($this->definitionTag, true);
         foreach ($taggedServices as $id => $tags) {
             foreach ($tags as $tag) {
-                if (!array_key_exists('name', $tag)) {
+                if (!\array_key_exists('name', $tag)) {
                     throw new RuntimeException(sprintf('The "name" for the tag "%s" of service "%s" must be set.', $this->definitionTag, $id));
                 }
-                if (!array_key_exists('type', $tag)) {
+                if (!\array_key_exists('type', $tag)) {
                     throw new RuntimeException(sprintf('The "type" for the tag "%s" of service "%s" must be set.', $this->definitionTag, $id));
                 }
-                if (!array_key_exists('marking_store', $tag)) {
+                if (!\array_key_exists('marking_store', $tag)) {
                     throw new RuntimeException(sprintf('The "marking_store" for the tag "%s" of service "%s" must be set.', $this->definitionTag, $id));
                 }
 
diff --git a/src/Symfony/Component/Workflow/Tests/Validator/StateMachineValidatorTest.php b/src/Symfony/Component/Workflow/Tests/Validator/StateMachineValidatorTest.php
index c43292899b..4e34456055 100644
--- a/src/Symfony/Component/Workflow/Tests/Validator/StateMachineValidatorTest.php
+++ b/src/Symfony/Component/Workflow/Tests/Validator/StateMachineValidatorTest.php
@@ -94,7 +94,7 @@ class StateMachineValidatorTest extends TestCase
 
         (new StateMachineValidator())->validate($definition, 'foo');
 
-        // the test simply ensures that the validation does not fail (i.e. it does not throw any exceptions)
+        // the test ensures that the validation does not fail (i.e. it does not throw any exceptions)
         $this->addToAssertionCount(1);
 
         // The graph looks like:
diff --git a/src/Symfony/Component/Workflow/Tests/Validator/WorkflowValidatorTest.php b/src/Symfony/Component/Workflow/Tests/Validator/WorkflowValidatorTest.php
index cdf10ecdab..4a5c5a57dd 100644
--- a/src/Symfony/Component/Workflow/Tests/Validator/WorkflowValidatorTest.php
+++ b/src/Symfony/Component/Workflow/Tests/Validator/WorkflowValidatorTest.php
@@ -29,7 +29,7 @@ class WorkflowValidatorTest extends TestCase
 
         (new WorkflowValidator(true))->validate($definition, 'foo');
 
-        // the test simply ensures that the validation does not fail (i.e. it does not throw any exceptions)
+        // the test ensures that the validation does not fail (i.e. it does not throw any exceptions)
         $this->addToAssertionCount(1);
     }
 
@@ -64,7 +64,7 @@ class WorkflowValidatorTest extends TestCase
 
         (new WorkflowValidator())->validate($definition, 'foo');
 
-        // the test simply ensures that the validation does not fail (i.e. it does not throw any exceptions)
+        // the test ensures that the validation does not fail (i.e. it does not throw any exceptions)
         $this->addToAssertionCount(1);
     }
 }
diff --git a/src/Symfony/Component/Yaml/Inline.php b/src/Symfony/Component/Yaml/Inline.php
index 1619b3183a..4b12b9b11a 100644
--- a/src/Symfony/Component/Yaml/Inline.php
+++ b/src/Symfony/Component/Yaml/Inline.php
@@ -555,7 +555,7 @@ class Inline
                 throw new ParseException('A reference must contain at least one character.', self::$parsedLineNumber + 1, $value, self::$parsedFilename);
             }
 
-            if (!array_key_exists($value, $references)) {
+            if (!\array_key_exists($value, $references)) {
                 throw new ParseException(sprintf('Reference "%s" does not exist.', $value), self::$parsedLineNumber + 1, $value, self::$parsedFilename);
             }
 
diff --git a/src/Symfony/Component/Yaml/Parser.php b/src/Symfony/Component/Yaml/Parser.php
index 04b00d9870..4519edb840 100644
--- a/src/Symfony/Component/Yaml/Parser.php
+++ b/src/Symfony/Component/Yaml/Parser.php
@@ -237,7 +237,7 @@ class Parser
                     $allowOverwrite = true;
                     if (isset($values['value'][0]) && '*' === $values['value'][0]) {
                         $refName = substr(rtrim($values['value']), 1);
-                        if (!array_key_exists($refName, $this->refs)) {
+                        if (!\array_key_exists($refName, $this->refs)) {
                             if (false !== $pos = array_search($refName, $this->refsBeingParsed, true)) {
                                 throw new ParseException(sprintf('Circular reference [%s, %s] detected for reference "%s".', implode(', ', \array_slice($this->refsBeingParsed, $pos)), $refName, $refName), $this->currentLineNb + 1, $this->currentLine, $this->filename);
                             }
@@ -653,7 +653,7 @@ class Parser
                 $value = substr($value, 1);
             }
 
-            if (!array_key_exists($value, $this->refs)) {
+            if (!\array_key_exists($value, $this->refs)) {
                 if (false !== $pos = array_search($value, $this->refsBeingParsed, true)) {
                     throw new ParseException(sprintf('Circular reference [%s, %s] detected for reference "%s".', implode(', ', \array_slice($this->refsBeingParsed, $pos)), $value, $value), $this->currentLineNb + 1, $this->currentLine, $this->filename);
                 }