still more to come to complete FFi support, but that part is done
btw #682, #566 and #817 should be closed
teach builtin proc how to handle nativefunction as bound_method
NativeFunction: handle FFI callback as return type
As a general remark, did you look into getting (more of) the specs to run so we can verify the behavior and make sure it doesn't break in the future?
I started working on FFI because I wanted my https://github.com/jeremyz/ffi-efl binding to work with rubinius.
Actually only :varargs parameter type is needed to complete this.
But in the meantime my target has changed and is now to be able to run spec/ruby/optional/ffi/*
So next step for me is to implement FFI::ManagedStruct and some might run.