[GHC] #10745: Error in fusion when compiling Data.Yaml

[GHC]

#10745: Error in fusion when compiling Data.Yaml
-----------------------------------------+---------------------------------
              Reporter:  nclarke         |             Owner:
                  Type:  bug             |            Status:  new
              Priority:  normal          |         Milestone:
             Component:  Compiler        |           Version:  7.10.2
              Keywords:                  |  Operating System:  Linux
          Architecture:  x86_64 (amd64)  |   Type of failure:  None/Unknown
             Test Case:                  |        Blocked By:
              Blocking:                  |   Related Tickets:
Differential Revisions:                  |
-----------------------------------------+---------------------------------
 {{{
 [2 of 7] Compiling Data.Yaml.Internal ( Data/Yaml/Internal.hs, dist/dist-
 sandbox-b22ce51e/build/Data/Yaml/Internal.o )

 Data/Yaml/Internal.hs:28:1: Warning:
     The import of ‘Control.Applicative’ is redundant
       except perhaps to import instances from ‘Control.Applicative’
     To import instances alone, use: import Control.Applicative()
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.10.2 for x86_64-unknown-linux):
         Tick in rule
   unstream
     @ a34_ayco
     @ Void
     @ m_aycm
     @ b_aycn
     (ConduitWithStream
        @ a34_ayco
        @ Void
        @ m_aycm
        @ b_aycn
        (let {
           $dApplicative_aycu :: Applicative (ConduitM a34_ayco Void
 m_aycm)
           [LclId, Str=DmdType]
           $dApplicative_aycu =
             $fApplicativeConduitM
               @ a34_ayco
               @ Void
               @ m_aycm
               ($fFunctorConduitM @ a34_ayco @ Void @ m_aycm) } in
         letrec {
           loop_aycv :: b_aycn -> ConduitM a34_ayco Void m_aycm b_aycn
           [LclId, Arity=1, Str=DmdType]
           loop_aycv =
             \ (accum_aycw :: b_aycn) ->
               $fMonadConduitM_$c>>=
                 @ a34_ayco
                 @ Void
                 @ m_aycm
                 $dApplicative_aycu
                 @ (Maybe a34_ayco)
                 @ b_aycn
                 ((await @ a34_ayco @ m_aycm $dMonad1_aycq) @ Void)
                 (maybe
                    @ (ConduitM a34_ayco Void m_aycm b_aycn)
                    @ a34_ayco
                    ($fMonadConduitM_$creturn
                       @ a34_ayco @ Void @ m_aycm $dApplicative_aycu @
 b_aycn accum_aycw)
                    (\ (a35_aycx :: a34_ayco) ->
                       $fMonadConduitM_$c>>=
                         @ a34_ayco
                         @ Void
                         @ m_aycm
                         $dApplicative_aycu
                         @ b_aycn
                         @ b_aycn
                         ($ @ (m_aycm b_aycn)
                            @ (ConduitM a34_ayco Void m_aycm b_aycn)
                            ($fMonadBasebaseConduitM_$clift
                               @ a34_ayco @ Void @ m_aycm @ b_aycn
 $dMonad1_aycq)
                            (f_aycs accum_aycw a35_aycx))
                         (\ (accum'_aycy :: b_aycn) ->
                            case accum'_aycy of wild_aycz { __DEFAULT ->
                            loop_aycv wild_aycz
                            }))); } in
         loop_aycv b1_ayct)
        (foldMS
           @ b_aycn @ a34_ayco @ m_aycm $dMonad1_aycq f_aycs b1_ayct @
 Void))

 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10745>
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