[FLEX-33913] XMLListCollection addItem(item) modifies a parent XMLList of the item

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Adobe Flex SDK 3.6 (Release), Adobe Flex SDK 4.1 (Release), Apache Flex 4.11.0
• Fix Version/s: Apache Flex 4.12.0
• Component/s: .Unspecified - Framework
• Labels: easytest
• Environment: Reproduced with the SDKs above in FP 11.9 on Windows IE; Likely an issue in all OS/SDK/FP combinations.
• Assignee: Justin Mclean
• Reporter: Stepan Hilbert
• Created: 19/Nov/13 04:07
• Updated: 04/Jan/14 01:57
• Resolved: 04/Jan/14 01:56

Description

Sample code:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" >
	<mx:Script>
		<![CDATA[
			import mx.collections.XMLListCollection;
			import mx.controls.Alert;
			protected var mainXML:XML = 
				<root>
					<item id="1"/>
					<item id="2"/>
					<item id="3"/>
				</root>;
			
			protected function addButton_clickHandler(event:MouseEvent):void
			{
				trace("Length before adding: " + mainXML.item.length()); // traces '3'
				var some:XMLListCollection = new XMLListCollection();
				for each (var o:Object in mainXML.item)	{
					some.addItem(o);
				}
				trace("Length After adding: " + mainXML.item.length()); // traces '5' BUT SHOULD BE STILL 3
			}
		]]>
	</mx:Script>
	<mx:Button label="Add Items" click="addButton_clickHandler(event)" />
</mx:Application>

Result:
mainXML.item XMLList is gets modified - the 2nd and 3rd items are added to it. That shouldn't happen and can cause very severe issues.

Workaround:
Do not use XMLListCollection. Array or ArrayCollection seem to be unaffected by this bug.

Related Issues:
This issue might share the same underlying cause: FLEX-21831