I have built a similar static analysis tool for Ruby. The result is a new open-source project RubySonar. RubySonar can now process the full Ruby standard library, Ruby on Rails, and Ruby apps such as Homebrew.
RubySonar’s analysis is inter-procedural and is sensitive to both data-flow and control-flow, which makes it highly accurate. RubSonar uses the same type inference technique of PySonar, and thus can resolve some of the difficult cases that can challenge a good Ruby IDE.