Remove all YAML references

UPGRADE.md

@@ -1,5 +1,10 @@
 # Upgrade to 3.0
 
+## BC Break: Removed ``YAML`` mapping drivers.
+
+If your code relies on ``YamlDriver``  or ``SimpleYamlDriver``, you should change to
+annotation or XML drivers instead.
+
 ## BC Break: Changed methods in ``ClassMetadata``
 
 * ``ClassMetadata::addInheritedProperty``

composer.json

@@ -24,13 +24,9 @@
         "symfony/console": "~2.5|~3.0"
     },
     "require-dev": {
-        "symfony/yaml": "~2.3|~3.0",
         "phpunit/phpunit": "^5.4",
         "phpbench/phpbench": "^0.11.2"
     },
-    "suggest": {
-        "symfony/yaml": "If you want to use YAML Metadata Mapping Driver"
-    },
     "autoload": {
         "psr-4": { "Doctrine\\ORM\\": "lib/Doctrine/ORM" }
     },

lib/Doctrine/ORM/Events.php

@@ -114,7 +114,7 @@ private function __construct()
 
     /**
      * The loadClassMetadata event occurs after the mapping metadata for a class
-     * has been loaded from a mapping source (annotations/xml/yaml).
+     * has been loaded from a mapping source (annotations/xml).
      *
      * @var string
      */

lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php

@@ -810,10 +810,10 @@ private function _getCascadeMappings(SimpleXMLElement $cascadeElement)
         /* @var $action SimpleXmlElement */
         foreach ($cascadeElement->children() as $action) {
             // According to the JPA specifications, XML uses "cascade-persist"
-            // instead of "persist". Here, both variations
-            // are supported because both YAML and Annotation use "persist"
-            // and we want to make sure that this driver doesn't need to know
-            // anything about the supported cascading actions
+            // instead of "persist". Here, both variations are supported
+            // because Annotation use "persist" and we want to make sure that
+            // this driver doesn't need to know anything about the supported
+            // cascading actions
             $cascades[] = str_replace('cascade-', '', $action->getName());
         }