Panic "ctEvTerm" when using functional dependencies and PolyKinds
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
.
Trac metadata
Trac field | Value |
---|---|
Version | 7.7 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |