Fix

Author: nicolas-grekas

src/Symfony/Component/Config/Resource/ReflectionClassResource.php

@@ -197,7 +197,7 @@ private function generateSignature(\ReflectionClass $class)
                         } else {
                             $t = \PHP_VERSION_ID >= 70000 ? $p->getType() : '';
                             $stack[] = $p->isOptional();
-                            $stack[] = $t instanceof \ReflectionNamedType ? $t->getName() : (string) $t;
+                            $stack[] = $t instanceof \ReflectionNamedType ? ((string) $t->allowsNull()).$t->getName() : (string) $t;
                             $stack[] = $p->isPassedByReference();
                             $stack[] = \PHP_VERSION_ID >= 50600 ? $p->isVariadic() : '';
                             $stack[] = $p->getName();

src/Symfony/Component/DependencyInjection/Compiler/FactoryReturnTypePass.php

@@ -93,7 +93,7 @@ private function updateDefinition(ContainerBuilder $container, $id, Definition $
 
         $returnType = $m->getReturnType();
         if (null !== $returnType && !$returnType->isBuiltin()) {
-            $returnType = $returnType instanceof \ReflectionNamedType ? $returnType->getName() : $returnType->__toString();
+            $returnType = $returnType instanceof \ReflectionNamedType ? $returnType->getName() : (string) $returnType;
             if (null !== $class) {
                 $declaringClass = $m->getDeclaringClass()->getName();
                 if ('self' === strtolower($returnType)) {

src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadataFactory.php

@@ -105,7 +105,7 @@ private function getType(\ReflectionParameter $parameter, \ReflectionFunctionAbs
             if (!$type = $parameter->getType()) {
                 return null;
             }
-            $name = $type instanceof \ReflectionNamedType ? $type->getName() : $type->__toString();
+            $name = $type instanceof \ReflectionNamedType ? $type->getName() : (string) $type;
             if ('array' === $name && !$type->isBuiltin()) {
                 // Special case for HHVM with variadics
                 return null;

src/Symfony/Component/OptionsResolver/OptionsResolver.php

@@ -1076,7 +1076,7 @@ private function getParameterClassName(\ReflectionParameter $parameter)
             return ($class = $parameter->getClass()) ? $class->name : null;
         }
 
-        if (!($type = $parameter->getType()) instanceof \ReflectionNamedType || $type->isBuiltin()) {
+        if (!($type = $parameter->getType()) || $type->isBuiltin()) {
             return null;
         }