ghc: panic! (the 'impossible' happened)

• *When I build my program I get this:**

play-0.1.0.0: build (exe)
Preprocessing executable 'play' for play-0.1.0.0...
[1 of 1] Compiling Main             ( src/Main.hs, .stack-work/dist/x86_64-linux-nopie/Cabal-1.24.2.0/build/play/play-tmp/Main.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.2 for x86_64-unknown-linux):
	initTc: unsolved constraints
  WC {wc_insol =
        [W] interactD_aL2 :: t_aL1[tau:1] (CHoleCan: interactD)
        [W] interactD_aLt :: t_aLs[tau:1] (CHoleCan: interactD)}

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

• *The code:**

{-# LANGUAGE GADTs #-}

module Main where

import Control.Monad.Trans.Cont
import Control.Monad.Trans.Class

--main :: IO ()

{-- CONTT --
main = evalContT contt

contt :: ContT () IO ()
contt = do
    k <- do
      callCC $ \exit -> do
        lift $ putStrLn "Entry"
        exit $ \_ -> do
          putStrLn "Exit"
    lift $ putStrLn "Inside"
    lift $ k ()
    
--}
{--
class Monad m => Interact m where
  get :: m String
  say :: String -> m ()

instance Interact IO where
  get = getLine
  say = putStrLn

prog :: Interact a => a ()
prog = do 
  say "Hello what is your name?"
  name <- get
  say $ "Hello " ++ name ++ ", I am prog! Goodbye"

main :: IO ()
main = prog
--}


data InteractD m = InteractD 
  { getD :: m String
  , sayD :: String -> m () 
  }

interactDIO :: InteractD IO
interactDIO = interactD getLine putStrLn

interactDIO2 :: InteractD IO
interactDIO2 = interactD (return "James") putStrLn

Trac metadata

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