#1999: panic with GADT etc.
-------------------------+--------------------------------------------------
Reporter: jeltsch | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.9
Severity: normal | Keywords:
Difficulty: Unknown | Testcase:
Architecture: x86 | Os: Linux
-------------------------+--------------------------------------------------
The following code causes a panic with GHC installed from
ghc-6.9.20071218-i386-unknown-linux.tar.bz2:
{{{
{-# LANGUAGE FlexibleContexts, FlexibleInstances, GADTs #-}
module Bug where
class C a where
f :: G a -> ()
instance (C ()) => C (b c) where
f (G x) = f x where
data G a where
G :: G () -> G (b c)
}}}
The output of ghci is:
{{{
GHCi, version 6.9.20071218: http://www.haskell.org/ghc/ :? for help
Loading package base ... linking ... done.
[1 of 1] Compiling Bug ( Bug.hs, interpreted )
ghc-6.9.20071218: panic! (the 'impossible' happened)
(GHC version 6.9.20071218 for i386-unknown-linux):
Coercion.splitCoercionKindOf
base:GHC.Prim.left{(w) tc 34B} $co${tc aog} [tv]
<pred>b{tv anB} [sk] ~ b{tv aoc} [sk]
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
The output of ghc -c is:
{{{
ghc-6.9.20071218: panic! (the 'impossible' happened)
(GHC version 6.9.20071218 for i386-unknown-linux):
Coercion.splitCoercionKindOf
base:GHC.Prim.left{(w) tc 34B} $co${tc a6t} [tv]
<pred>b{tv a5O} [sk] ~ b{tv a6p} [sk]
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1999>
GHC <http://www.haskell.org/ghc/>
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