[Form] Fixed PropertyPath to not modify Collection instances (not even their clones)

Author: webmozart

src/Symfony/Component/Form/Tests/Util/PropertyPathCollectionTest.php

@@ -168,6 +168,7 @@ public function testSetValueCallsAdderAndRemoverForCollections()
  $axesBefore = $this->getCollection(array(1 => 'second', 3 => 'fourth', 4 => 'fifth'));
  $axesMerged = $this->getCollection(array(1 => 'first', 2 => 'second', 3 => 'third'));
  $axesAfter = $this->getCollection(array(1 => 'second', 5 => 'first', 6 => 'third'));
+ $axesMergedCopy = is_object($axesMerged) ? clone $axesMerged : $axesMerged;
 
  // Don't use a mock in order to test whether the collections are
  // modified while iterating them
@@ -178,6 +179,9 @@ public function testSetValueCallsAdderAndRemoverForCollections()
  $path->setValue($car, $axesMerged);
 
  $this->assertEquals($axesAfter, $car->getAxes());
+
+ // The passed collection was not modified
+ $this->assertEquals($axesMergedCopy, $axesMerged);
  }
 
  public function testSetValueCallsAdderAndRemoverForNestedCollections()

src/Symfony/Component/Form/Util/PropertyPath.php

@@ -485,7 +485,9 @@ private function writeProperty(&$objectOrArray, $property, $singular, $isIndex,
  $methods = $this->findAdderAndRemover($reflClass, $singulars);
  if (null !== $methods) {
  // At this point the add and remove methods have been found
- $itemsToAdd = is_object($value) ? clone $value : $value;
+ // Use iterator_to_array() instead of clone in order to prevent side effects
+ // see https://github.com/symfony/symfony/issues/4670
+ $itemsToAdd = is_object($value) ? iterator_to_array($value) : $value;
  $itemToRemove = array();
  $propertyValue = $this->readProperty($objectOrArray, $property, $isIndex);
  $previousValue = $propertyValue[self::VALUE];