[GHC] #11334: GHC panic when calling typeOf on a promoted data constructor

[GHC]

#11334: GHC panic when calling typeOf on a promoted data constructor
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        Reporter:  RyanGlScott       |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  8.0.1-rc1
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1757
       Wiki Page:                    |
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Comment (by bgamari):

 This fails,

 {{{#!hs
 {-# LANGUAGE DataKinds #-}
 import Data.Typeable
 import Data.Functor.Compose
 main :: IO ()
 main = print $ typeOf (undefined :: Proxy 'Compose)
 }}}

 with a compiler panic due to `TcInteract.mk_typeable_pred` calling
 `typeKind` on an ill-kinded type, `TYPE 'Lifted (TYPE 'Lifted *) ->
 Compose * * *`. Note the application `TYPE 'Lifted (TYPE 'Lifted *)`,
 which oversaturates `TYPE`. The problem here is apparently that the kind
 variables of `Compose` are all instantiated with `*` with `-XNoPolyKinds`
 I haven't yet determined where this occurs.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11334#comment:8>
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