the 'impossible' happened, initTc: unsolved constraints

Compile simple program using stack: stack ghc Main.hs

code:

import Control.Monad.Writer.Strict

logNumber :: Int -> Writer [String] Int  
logNumber x = Writer (x, ["Got number: " ++ show x])  

multWithLog :: Writer [String] Int  
multWithLog = do  
  a <- logNumber 3  
  b <- logNumber 5  
  tell ["Gonnay multiply these two"]
  return (a*b)  

[1 of 1] Compiling Main             ( Main.hs, Main.o )                 
ghc: panic! (the 'impossible' happened)                                 
  (GHC version 8.0.2 for x86_64-unknown-linux):                         
        initTc: unsolved constraints                                    
  WC {wc_insol = [W] Writer_a19y :: t_a19x[tau:1] (CHoleCan: Writer)}   

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