#7384: Panic "ctEvTerm" when using functional dependencies and PolyKinds
------------------------------+---------------------------------------------
Reporter: goldfire | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.7 | Keywords: FunctionalDependencies
PolyKinds
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: None/Unknown | Testcase:
Blockedby: | Blocking:
Related: |
------------------------------+---------------------------------------------
The following code causes a panic:
{{{
{-# LANGUAGE FunctionalDependencies, PolyKinds #-}
class Baz a b | a -> b where
bar :: a -> ()
instance Baz Bool Bool where
bar _ = ()
foo = bar False
}}}
The panic reads:
{{{
ghc: panic! (the 'impossible' happened)
(GHC version 7.7.20121031 for x86_64-apple-darwin):
ctEvTerm: derived constraint cannot have id
<<details unavailable>>
}}}
The panic does not happen without {{{-XPolyKinds}}}.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7384>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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