[GHC] #10403: GHC crashes on a partial type signature

[GHC]

#10403: GHC crashes on a partial type signature
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        Reporter:  Artyom.Kazak      |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash                              |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by Artyom.Kazak):

 Error message (in GHCi 7.10.1):

 {{{#!hs
 $ ghci
 GHCi, version 7.10.1: http://www.haskell.org/ghc/  :? for help
 Prelude Control.Applicative Control.Monad Data.Ratio> :l Bug.hs
 [1 of 1] Compiling Main             ( Bug.hs, interpreted )

 Bug.hs:18:10:
     Couldn't match type `b' with `H I'
       `b' is untouchable
         inside the constraints ()
         bound by the type signature for app :: H (B t)
         at Bug.hs:17:8-14ghc: panic! (the 'impossible' happened)
   (GHC version 7.10.1 for x86_64-unknown-linux):
     No skolem info: b_aFd[sk]

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10403#comment:4>
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