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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
  • GHCGHC
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  • #15817
Closed
Open
Issue created Oct 27, 2018 by Icelandjack@IcelandjackReporter

Data family quantification = GHC panic, ‘impossible’ happened

{-# Language RankNTypes       #-}
{-# Language TypeApplications #-}
{-# Language PolyKinds        #-}
{-# Language KindSignatures   #-}
{-# Language TypeFamilies     #-}

data family   Pair :: forall a. forall b. *
data instance Pair @a @b = MkPair a b
$ ghci -ignore-dot-ghci 593_bug.hs
GHCi, version 8.7.20181017: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( 593_bug.hs, interpreted )
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 8.7.20181017 for x86_64-unknown-linux):
        ASSERT failed!
  kind axiom D:R:Pairabab0 ::
         forall a b (a :: a) (b :: b).
           Pair = R:Pairabab -- Defined at 593_bug.hs:8:15
  forall k k (a :: k) (b :: k). *
  forall a b -> a -> b -> *
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable
        pprPanic, called at compiler/utils/Outputable.hs:1219:5 in ghc:Outputable
        assertPprPanic, called at compiler/typecheck/FamInst.hs:158:61 in ghc:FamInst

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

>
Trac metadata
Trac field Value
Version 8.6.1
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC mnguyen
Operating system
Architecture
Edited Mar 10, 2019 by Icelandjack
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