Duplicate objects in collection of nested objects with multiple references

[klammbueddel]

Bug Report

Given 3 classes, a Container containing a list of Items and each item containing multiple Parts, if the container references both, the complete list of items ($container->items) and points to one item in the list ($container->currentItem), the parts of the item will be duplicated in the result set if fetched via DQL.

As a sidenote, the issue does not occur if the objects are already managed (see testIfAlreadyManaged in #9580).

Q	A
BC Break	no
Version	2.11.2

How to reproduce

$container = new Container();

# a container has items
$item = new Item();
$item->container = $container;
$container->items[]= $item;

# the container has a pointer on one item in the list of items
$container->currentItem = $item;

# an item has parts
$part = new Part();
$part->item = $item;
$item->parts[] = $part

$dql = <<<DQL
SELECT container, currentItem, currentItemPart, item, itemPart 
FROM Container container
LEFT JOIN container.currentItem currentItem
LEFT JOIN currentItem.parts currentItemPart  
LEFT JOIN container.items item 
LEFT JOIN item.parts itemPart
DQL;

# this test will fail
$containers = $this->_em->createQuery($dql)->execute();
self::assertCount(1, $containers);
self::assertCount(1, $containers[0]->items);
self::assertCount(1, $containers[0]->items[0]->parts); # << the item will contain 2 parts

Expected behavior

The $item->parts should not contain duplicates.

[klammbueddel]

Hi,
would be great if somebody could review the PR.
Thanks ;)