[GHC] #13117: Derived functor instance for void types handles errors badly

[GHC]

#13117: Derived functor instance for void types handles errors badly
-------------------------------------+-------------------------------------
        Reporter:  dfeuer            |                Owner:  dfeuer
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by andreas.abel):

 What should the implementation of `fmap` be here?
 {{{#!hs
 fmap _ x = x `seq` error "Void fmap"
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13117#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler