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 FalseThe 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 | |
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| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |