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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
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  • #12423
Closed
Open
Issue created Jul 22, 2016 by knrafto@trac-knrafto

Panic with DeriveAnyClass

With the code

{-# LANGUAGE DefaultSignatures, DeriveAnyClass #-}
class Eq1 f where
  (==#) :: Eq a => f a -> f a -> Bool
  default (==#) :: Eq (f a) => f a -> f a -> Bool
  (==#) = (==)

data Foo a = Foo (Either a a)
    deriving (Eq, Eq1)

GHC 8.0.1 and 7.10.3 both panic:

ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.1 for x86_64-apple-darwin):
	in other argument

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Trac metadata
Trac field Value
Version 8.0.1
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler
Test case
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Architecture
Edited Mar 10, 2019 by David Feuer
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