[Form] raise exception when label for choice cannot be read

src/Symfony/Component/Form/Extension/Core/ChoiceList/ChoiceList.php

@@ -254,12 +254,17 @@ class ChoiceList implements ChoiceListInterface
      * @param array              $labels             The labels corresponding to the choices.
      * @param array              $preferredChoices   The preferred choices.
      *
+     * @throws \InvalidArgumentException     If the structures of the choices and labels array do not match.
      * @throws InvalidConfigurationException If no valid value or index could be created for a choice.
      */
     protected function addChoices(array &$bucketForPreferred, array &$bucketForRemaining, $choices, array $labels, array $preferredChoices)
     {
         // Add choices to the nested buckets
         foreach ($choices as $group => $choice) {
+            if (!isset($labels[$group])) {
+                throw new \InvalidArgumentException('The structures of the choices and labels array do not match.');
+            }
+
             if (is_array($choice)) {
                 // Don't do the work if the array is empty
                 if (count($choice) > 0) {

src/Symfony/Component/Form/Tests/Extension/Core/ChoiceList/ChoiceListTest.php

@@ -173,4 +173,15 @@ class ChoiceListTest extends \PHPUnit_Framework_TestCase
         $choices = array($this->obj2, $this->obj3, 'foobar');
         $this->assertSame(array('1', '2'), $this->list->getValuesForChoices($choices));
     }
+
+    /**
+     * @expectedException \InvalidArgumentException
+     */
+    public function testNonMatchingLabels()
+    {
+        $this->list = new ChoiceList(
+            array($this->obj1, $this->obj2),
+            array('A')
+        );
+    }
 }