Bug 2146 - NullReferenceException when calling Remove() extension method
Summary: NullReferenceException when calling Remove() extension method
Status: RESOLVED FIXED
Alias: None
Product: Class Libraries
Classification: Mono
Component: System.XML ()
Version: 2.10.x
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2011-11-21 19:52 UTC by Marc Gallagher
Modified: 2012-01-19 05:53 UTC (History)
2 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:


Attachments
Example code (730 bytes, text/plain)
2011-11-21 19:52 UTC, Marc Gallagher
Details


Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.


Please create a new report on GitHub or Developer Community with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:
Status:
RESOLVED FIXED

Description Marc Gallagher 2011-11-21 19:52:49 UTC
Created attachment 924 [details]
Example code

The MSDN documentation for System.Xml.Linq.Extensions.Remove() (http://msdn.microsoft.com/en-us/library/bb357554(v=VS.90).aspx) has the following in the remarks section:

"This method uses snapshot semantics—that is, it copies the nodes in the source collection to a List<T> before disconnecting them from their parents. This is required to avoid issues with mixed imperative/declarative code."

However, Mono's version does not take similar precautions which can lead to the enumerator being placed in an inconsistent state. This is especially noticeable when using NodesBeforeSelf() and NodesAfterSelf().

The attached code fragment demonstrates the issue.
Comment 1 Atsushi Eno 2012-01-19 05:53:01 UTC
That's a good catch. Fixed in git master df47a23. Thanks for the report.