Segfaults on levity-polymorphic type class
{-# Language FlexibleInstances, TypeFamilies, TypeInType, MagicHash #-}
import Data.Kind
import GHC.Exts
class Shw (a :: TYPE rep) where
shw :: a -> String
instance Int# ~ a => Shw (a :: TYPE IntRep) where
shw a = "I#" ++ show (I# a)
main = putStrLn (shw 3#)induces a segfault
$ runghc --version
runghc 8.0.1
$ runghc test.hs
I#Segmentation faultTrac metadata
| Trac field | Value |
|---|---|
| Version | 8.0.1 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |