From caca373383ba15aae7084a73bb22c68d3f164cd8 Mon Sep 17 00:00:00 2001
From: Christian Flothmann <christian.flothmann@sensiolabs.de>
Date: Tue, 15 Jan 2019 14:43:24 +0100
Subject: [PATCH] the string "0" is a valid service identifier

---
 .../Component/DependencyInjection/Loader/XmlFileLoader.php    | 4 ++--
 .../DependencyInjection/Tests/Fixtures/xml/services6.xml      | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
index 4236b72f252a..4677a61ca4c1 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
@@ -496,7 +496,7 @@ private function getArgumentsAsPhp(\DOMElement $node, $name, $file, $lowercase =
 
             switch ($arg->getAttribute('type')) {
                 case 'service':
-                    if (!$arg->getAttribute('id')) {
+                    if ('' === $arg->getAttribute('id')) {
                         throw new InvalidArgumentException(sprintf('Tag "<%s>" with type="service" has no or empty "id" attribute in "%s".', $name, $file));
                     }
                     if ($arg->hasAttribute('strict')) {
@@ -549,7 +549,7 @@ private function getArgumentsAsPhp(\DOMElement $node, $name, $file, $lowercase =
      * @param \DOMNode $node
      * @param mixed    $name
      *
-     * @return array
+     * @return \DOMElement[]
      */
     private function getChildren(\DOMNode $node, $name)
     {
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
index cffd5df6059a..c85b7a7c01ef 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services6.xml
@@ -61,5 +61,9 @@
     </service>
     <service id="alias_for_foo" alias="foo" />
     <service id="another_alias_for_foo" alias="foo" public="false" />
+    <service id="0" class="FooClass" />
+    <service id="1" class="FooClass">
+      <argument type="service" id="0" />
+    </service>
   </services>
 </container>