[GHC] #10176: Invalid core generated with GHC 7.10 RC3

[GHC]

#10176: Invalid core generated with GHC 7.10 RC3
-------------------------------------+-------------------------------------
        Reporter:  NeilMitchell      |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.1
       Component:  Compiler          |                 Version:  7.10.1-rc3
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by nomeata):

 Also, changing the code to
 {{{
 newtype Fun a b = Fun { runFun :: a -> b }
 type ReaderT r x = Fun r (IO x)
 }}}
 makes the problem go away. Must be some weird interaction with
 coercions...

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10176#comment:14>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler