GHC panic: newtype F rep = F (forall (a :: TYPE rep). a)

{-# Language RankNTypes     #-}
{-# Language KindSignatures #-}
{-# Language PolyKinds      #-}

import GHC.Exts

newtype Foo rep = MkFoo (forall (a :: TYPE rep). a)

$ ~/code/unmodifiedghc/inplace/bin/ghc-stage2 --interactive -ignore-dot-ghci /tmp/U.hs
GHCi, version 8.7.20181029: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( /tmp/U.hs, interpreted )
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 8.7.20181029 for x86_64-unknown-linux):
        isUnliftedType
  forall (a :: TYPE rep_a1AA[sk:0]). a :: TYPE rep_a1AA[sk:0]
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable
        pprPanic, called at compiler/types/Type.hs:2332:10 in ghc:Type
        isUnliftedType, called at compiler/typecheck/TcTyClsDecls.hs:3055:25 in ghc:TcTyClsDecls

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

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Trac metadata

Trac field	Value
Version	8.6.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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