Integrating CanCan with Sinatra 1.3 / DataMapper 1.2 / Ruby 1.9.2, I encountered this error. This change fixes it, but I haven't tested with an alternate stack.
fix uninitialized constant warning in CanCan::Rule#model_adapter
The test suite passes against the RVM instance.
cc @ryanb What are you thoughts?
I don't see why adding the CanCan namespace here would fix this, but perhaps there was some naming conflict somewhere causing a problem. Either way this shouldn't break anything - merging in.