GSoC/GCI Archive
Google Code-in 2010 Mono Project

Gendarme rule to avoid unneeded overrides

completed by: Nagato Yuki

mentors: spouliot


Gendarme is a static analysis tool to find problems in .NET software. Gendarme inspects executables and libraries that contain code in ECMA CIL format (Mono and .NET) and looks for common problems with the code, problems that compiler do not typically check or have not historically checked.



The task is to write one Gendarme rule that check if unneeded overrides are present in types since the extra call degrades performance. In particular this rule must check all overriding methods to see if they actually do something and not just call the base class.

Bad example:
public override string ToString ()
   return base.ToString ();

Note that this is quite common on the .NET framework and there are some good reason for them - so the rule must also check for:

  • extra attributes on the override;
  • extra security declaration (they aren't attributes even if they look like them) on the override;

but if they are identical to the base class, then the rule must warn about them.



To complete the task the student must provide:

*  the rules, written in C#. The source code must follow the Mono source code guidelines (available at Also a 'self-check' must be done one the code (i.e. you need to run gendarme on your own code) and the defects, if any, must be fixed (in doubt please ask for guidance on IRC).

* its documentation (in-source xmldoc) that includes 'good' and 'bad' examples; and

* the unit tests (also in C# using the gendarme helpers around NUnit) proving the rule is working as intended

Once ready the files (or the patch) can be submitted to the mentor for review.



* In order to avoid misunderstandings you should start by writing your unit tests and ask for a review of them. That will quickly tell you if you're on the right path to solve the problem.

* Gendarme provides hundreds of rules that can be used as example, here's one





* Gendarme web site:

* Mailing-list / discussions:

* IRC: #gendarme on GimpNET