[GHC] #13300: panic! isInjectiveTyCon sees a TcTyCon W

[GHC]

#13300: panic! isInjectiveTyCon sees a TcTyCon W
-------------------------------------+-------------------------------------
           Reporter:  siddhanathan   |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Compile-time
  Unknown/Multiple                   |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 The following code causes the compiler to panic

 {{{
 #!haskell
 {-# 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
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13300>
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