[GHC] #12866: GHC internal error while building darcsden

[GHC]

#12866: GHC internal error while building darcsden
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        Reporter:  simonmic          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |
      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:                    |
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Changes (by bgamari):

 * component:  Compiler => Compiler (Type checker)
 * milestone:   => 8.2.1


@@ -2,1 +2,1 @@
-
+ {{{
@@ -34,0 +34,1 @@
+ }}}

New description:

 I get an internal error while building darcsden with GHC 8.0.1:
 {{{
 $ darcs get hub.darcs.net:simon/darcsden-ghc8
 $ cd darcsden-ghc8
 $ stack --stack-yaml=stack-ghc8.yaml build
 ...
 [12 of 56] Compiling DarcsDen.Backend.Transient (
 src/DarcsDen/Backend/Transient.hs, .stack-
 work/dist/i386-linux/Cabal-1.24.0.0/build/DarcsDen/Backend/Transient.o )

 /home/simon/src/darcsden/src/DarcsDen/Backend/Transient.hs:10:33: error:
     • GHC internal error: ‘BackendTransientM’ is not in scope during type
 checking, but it passed the renamer
       tcl_env of environment: [ajE2 :-> Type variable ‘bt’ = bt]
     • In the first argument of ‘MonadIO’, namely ‘BackendTransientM bt’
       In the type ‘(BT bt, MonadIO (BackendTransientM bt))’
       In the type declaration for ‘BTIO’

 /home/simon/src/darcsden/src/DarcsDen/Backend/Transient.hs:44:1: error:
     • Non type-variable argument
         in the constraint: Functor (BackendTransientM bt)
       (Use FlexibleContexts to permit this)
     • In the context: (Functor (BackendTransientM bt),
                        Monad (BackendTransientM bt))
       While checking the super-classes of class ‘BackendTransient’
       In the class declaration for ‘BackendTransient’

 --  While building package darcsden-1.1.99 using:
       /home/simon/.stack/setup-exe-cache/i386-linux/setup-Simple-
 Cabal-1.24.0.0-ghc-8.0.1 --builddir=.stack-
 work/dist/i386-linux/Cabal-1.24.0.0 build lib:darcsden exe:darcsden exe
 :darcsden-post-hook exe:da...
     Process exited with code: ExitFailure 1
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12866#comment:2>
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