[GHC] #9193: GHC panic usinig HList and Lens

[GHC]

#9193: GHC panic usinig HList and Lens
-------------------------------------------+-------------------------------
       Reporter:  maxigit                  |             Owner:
           Type:  bug                      |            Status:  new
       Priority:  normal                   |         Milestone:
      Component:  Compiler                 |           Version:  7.6.3
       Keywords:                           |  Operating System:
   Architecture:  x86                      |  Unknown/Multiple
     Difficulty:  Easy (less than 1 hour)  |   Type of failure:  GHCi crash
     Blocked By:                           |         Test Case:
Related Tickets:                           |          Blocking:
-------------------------------------------+-------------------------------
 This bug might have been fixed in GHC 7.8.2 but I haven't been able to
 test it. Some packages required to reproduce the bug are broken under
 7.8.*.

 GHC 'panic' whilst trying to compile the following.
 Strangely, removing doing the last line of code 'manually' in ghci works.


 {{{
 {-# LANGUAGE TypeFamilies, DataKinds, PolyKinds, TypeOperators #-}
 {-# LANGUAGE NoMonomorphismRestriction #-}
 module Database.Harehouse.SQLFragment where
 import Data.HList
 import Control.Lens hiding(from)

 x = hLens' (Label :: Label "x")
 }}}

 Note. I'm using HList-0.3.4.1 and lens-4.1.2.1. I think it wasn't working
 with lens 4.2 either, but since I tried to install ghc 7.8.2 I haven't be
 able to reinstall lens 4.2. (cabal hell).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9193>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler