Merge branch '5.0' into 5.1

* 5.0: (28 commits)
  [Cache] $lifetime cannot be null
  [Serializer] minor cleanup
  fix merge
  Run PHP 8 as 7.4.99
  Remove calls to deprecated ReflectionParameter::getClass().
  [VarDumper] fix PHP 8 support
  Add php 8 to travis.
  [Cache] Accessing undefined constants raises an Error in php8
  [Cache] allow DBAL v3
  Skip Doctrine DBAL on php 8 until we have a compatible version.
  [DomCrawler] Catch expected ValueError.
  Made method signatures compatible with their corresponding traits.
  [ErrorHandler] Apply php8 fixes from Debug component.
  [DomCrawler] Catch expected ValueError.
  [Validator] Catch expected ValueError.
  [VarDumper] ReflectionFunction::isDisabled() is deprecated.
  [BrowserKit] Raw body with custom Content-Type header
  [PropertyAccess] Parse php 8 TypeErrors correctly.
  [Intl] Fix call to ReflectionProperty::getValue() for static properties.
  [HttpKernel] Prevent calling method_exists() with non-string values.
  ...

Author: nicolas-grekas

OptionsResolver.php

@@ -185,7 +185,7 @@ public function setDefault(string $option, $value)
             $reflClosure = new \ReflectionFunction($value);
             $params = $reflClosure->getParameters();
 
-            if (isset($params[0]) && null !== ($class = $params[0]->getClass()) && Options::class === $class->name) {
+            if (isset($params[0]) && Options::class === $this->getParameterClassName($params[0])) {
                 // Initialize the option if no previous value exists
                 if (!isset($this->defaults[$option])) {
                     $this->defaults[$option] = null;
@@ -206,7 +206,7 @@ public function setDefault(string $option, $value)
                 return $this;
             }
 
-            if (isset($params[0]) && null !== ($class = $params[0]->getClass()) && self::class === $class->name && (!isset($params[1]) || (null !== ($class = $params[1]->getClass()) && Options::class === $class->name))) {
+            if (isset($params[0]) && null !== ($type = $params[0]->getType()) && self::class === $type->getName() && (!isset($params[1]) || (null !== ($type = $params[1]->getType()) && Options::class === $type->getName()))) {
                 // Store closure for later evaluation
                 $this->nested[$option][] = $value;
                 $this->defaults[$option] = [];
@@ -1280,4 +1280,13 @@ private function formatOptions(array $options): string
 
         return implode('", "', $options);
     }
+
+    private function getParameterClassName(\ReflectionParameter $parameter): ?string
+    {
+        if (!($type = $parameter->getType()) || $type->isBuiltin()) {
+            return null;
+        }
+
+        return $type->getName();
+    }
 }