Bug imported from [C2HS Trac](http://hackage.haskell.org/trac/c2hs/ticket/47) Trac ticket created: 2012-07-04T15:17:44-0700 --- Declaring a {# fun ... #} with return type `()' leads to the following warning from GHC: Warning: Defined but not used: `res' Please consider either using res or declaring it as _ in this case, to prevent the warning.
