colinyoung/cancan_strong_parameters — pull request #5 by ronen (2013-02-12 14:28:52+00:00)
Title: Ensure strong_parameters defines Parameters first

It seems that in my setup bundler was causing cancan_strong_parameters to be required before strong_parameters. So this file defined ActionController::Parameters as a new class, rather than including a module in an existing class. Which meant that when strong_parameters tried to define ActionController::Parameters as a subclass of HashWithIndifferentAccess, ruby raised a 'superclass mismatch' error.

Requiring 'strong_parameters' here fixed the problem for me. (Though there may be more sophisticated ways of ensuring load order.)