panic! isInjectiveTyCon sees a TcTyCon W

The following code causes the compiler to panic

{-# LANGUAGE GADTs #-}

data W where
  WI :: Int
  WD :: Double

data Superblock
  = A { f :: W }
  | B { f :: W }

[1 of 1] Compiling Main             ( src/Main.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.2.0/build/hdf5/hdf5-tmp/Main.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.2 for x86_64-unknown-linux):
	isInjectiveTyCon sees a TcTyCon W

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


--  While building package hdf5-0.1.0.0 using:
      /home/siddhu/.stack/setup-exe-cache/x86_64-linux/setup-Simple-Cabal-1.24.2.0-ghc-8.0.2 --builddir=.stack-work/dist/x86_64-linux/Cabal-1.24.2.0 build exe:hdf5 --ghc-options " -ddump-hi -ddump-to-file"
    Process exited with code: ExitFailure 1

Trac metadata

Trac field	Value
Version	8.0.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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