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Panic with piResultTys1 again

The code

{-# LANGUAGE RankNTypes, TypeFamilies #-}

module Panic where

class C a where
  data T a
  panic :: (forall s . T a) -> ()

instance C () where
  data T () = T
  panic T = ()

produces the output

ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.1 for x86_64-apple-darwin):
	piResultTys1
  R:T()
  [Any]
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
Architecture
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