Unacceptable result type in FFI

[Neal Alexander]

How do you get Haddock 2.4 to handle the return type of an FFI function 
that isnt "IO". It works automatically in the haddock version that ships 
with ghc 6.8.1.

I tried:

haddock --haddock-options=--optghc=-XGeneralizedNewtypeDe
riving