ghci cause panic on 8.0.1

The following code panics when called with ghci:

module Foo where

import GHC.TypeLits (Symbol)
import Unsafe.Coerce

instance Read Symbol where
    readsPrec = unsafeCoerce (readsPrec :: Int -> ReadS String)

data Bar = TyCon !Symbol deriving (Read)

% ghci foo.hs                                                                                                                                                                                                                            
GHCi, version 8.0.1: http://www.haskell.org/ghc/  :? for help
Loaded GHCi configuration from /home/zv/.ghc/ghci.conf
[1 of 1] Compiling Foo              ( foo.hs, interpreted )
ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.1 for x86_64-unknown-linux):
	atomPrimRep case a1_s2AG of _ [Occ=Dead] { }

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Unknown/Multiple
Architecture