Merge branch '2.8' into 3.0

* 2.8:
  Updated all the README files
  [TwigBundle] Fix failing test on appveyor
  Improved the error message when using "@" in a decorated service
  Improve error reporting in router panel of web profiler
  [DoctrineBridge][Form] Fix performance regression in EntityType
  [FrameworkBundle] Fix a regression in handling absolute and namespaced template paths
  Allow to normalize \Traversable
  minor [Form] fix tests added by #16886
  Remove _path from query parameters when fragment is a subrequest and request attributes are already set Added tests for _path removal in FragmentListener
  Simplified everything
  Added a test
  Fixed the problem in an easier way
  Fixed a syntax issue
  Improved the error message when a template is not found
  [CodingStandards] Conformed to coding standards
  [TwigBundle] fixed Include file locations in "Template could not be found" exception

Author: fabpot

Encoder/XmlEncoder.php

@@ -366,7 +366,7 @@ private function buildXml(\DOMNode $parentNode, $data, $xmlRootNodeName = null)
     {
         $append = true;
 
-        if (is_array($data) || $data instanceof \Traversable) {
+        if (is_array($data) || ($data instanceof \Traversable && !$this->serializer->supportsNormalization($data, $this->format))) {
             foreach ($data as $key => $data) {
                 //Ah this is the magic @ attribute types.
                 if (0 === strpos($key, '@') && is_scalar($data) && $this->isElementNameValid($attributeName = substr($key, 1))) {

README.md

@@ -1,15 +1,16 @@
 Serializer Component
 ====================
 
-With the Serializer component it's possible to handle serializing data structures,
-including object graphs, into array structures or other formats like XML and JSON.
-It can also handle deserializing XML and JSON back to object graphs.
+With the Serializer component it's possible to handle serializing data
+structures, including object graphs, into array structures or other formats like
+XML and JSON. It can also handle deserializing XML and JSON back to object
+graphs.
 
 Resources
 ---------
 
-You can run the unit tests with the following command:
-
-    $ cd path/to/Symfony/Component/Serializer/
-    $ composer install
-    $ phpunit
+  * [Documentation](https://symfony.com/doc/current/components/serializer.html)
+  * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+  * [Report issues](https://github.com/symfony/symfony/issues) and
+    [send Pull Requests](https://github.com/symfony/symfony/pulls)
+    in the [main Symfony repository](https://github.com/symfony/symfony)

Tests/Encoder/XmlEncoderTest.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\Serializer\Tests\Encoder;
 
 use Symfony\Component\Serializer\Tests\Fixtures\Dummy;
+use Symfony\Component\Serializer\Tests\Fixtures\NormalizableTraversableDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\ScalarDummy;
 use Symfony\Component\Serializer\Encoder\XmlEncoder;
 use Symfony\Component\Serializer\Serializer;
@@ -248,6 +249,21 @@ public function testEncodeSerializerXmlRootNodeNameOption()
         $this->assertEquals($expected, $serializer->serialize($array, 'xml', $options));
     }
 
+    public function testEncodeTraversableWhenNormalizable() {
+        $this->encoder = new XmlEncoder();
+        $serializer = new Serializer(array(new CustomNormalizer()), array('xml' => new XmlEncoder()));
+        $this->encoder->setSerializer($serializer);
+
+        $expected = <<<XML
+<?xml version="1.0"?>
+<response><foo>normalizedFoo</foo><bar>normalizedBar</bar></response>
+
+XML;
+
+        $this->assertEquals($expected, $serializer->serialize(new NormalizableTraversableDummy(), 'xml'));
+
+    }
+
     public function testDecode()
     {
         $source = $this->getXmlSource();