Ill-kinded instance head involving -XTypeInType can invoke GHC panic
This code:
{-# LANGUAGE FlexibleInstances, TypeInType #-}
module FvProvFallsIntoAHole where
import Data.Kind
newtype UhOh (k :: * -> *) (a :: k *) = UhOh (k *)
instance Functor k => Functor (UhOh k) where
produces this GHC panic:
$ /opt/ghc/head/bin/ghc FvProvFallsIntoAHole.hs
[1 of 1] Compiling FvProvFallsIntoAHole ( FvProvFallsIntoAHole.hs, FvProvFallsIntoAHole.o )
ghc: panic! (the 'impossible' happened)
(GHC version 8.1.20160108 for x86_64-unknown-linux):
fvProv falls into a hole {aq6}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Trac metadata
Trac field | Value |
---|---|
Version | 8.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler (Type checker) |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | goldfire |
Operating system | |
Architecture |