[GHC] #8929: Deriving Generics broken

[GHC]

#8929: Deriving Generics broken
----------------------------------+-------------------------------------
       Reporter:  guest           |             Owner:
           Type:  bug             |            Status:  new
       Priority:  normal          |         Milestone:
      Component:  Compiler        |           Version:  7.6.3
       Keywords:                  |  Operating System:  Unknown/Multiple
   Architecture:  x86_64 (amd64)  |   Type of failure:  None/Unknown
     Difficulty:  Unknown         |         Test Case:
     Blocked By:                  |          Blocking:
Related Tickets:                  |
----------------------------------+-------------------------------------
 I load the following code into ghci:

 ==
 {-# LANGUAGE DeriveGeneric #-}

 import GHC.Generics
 import Data.Binary

 data Foo = Foo deriving (Show, Generic)

 instance Binary Foo
 ==

 Then I execute:

 (decode . encode $ Foo) :: Foo

 In 7.6.3 (stage 2 booted 7.6.3), I get an error.

 In 7.6.3 (stage 2 booted 7.6.2), the desired result "Foo" is shown.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8929>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler