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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
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  • #9222
Closed
Open
Issue created Jun 21, 2014 by Edward Kmett@ekmett

Unexpected DataKind Panic

Here's a simplified version of a panic I'm getting:

{-# LANGUAGE RankNTypes, GADTs, DataKinds, PolyKinds, TypeOperators, TypeFamilies #-}
import Data.Proxy
data Want :: (i,j) -> * where
  Want :: (a ~ '(b,c) => Proxy b) -> Want a
GHCi, version 7.8.2: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
ghc: panic! (the 'impossible' happened)
  (GHC version 7.8.2 for x86_64-apple-darwin):
	tcTyVarDetails k{tv aAv} [tv]

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Trac metadata
Trac field Value
Version 7.8.2
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler (Type checker)
Test case
Differential revisions
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CC ekmett
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