#12709: GHC panic -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by nfrisby): I don't know if it's exactly the same as this ticket, but I get a similar panic from the following minimization. {{{#!hs {-# Language TypeFamilies, TypeInType #-} import Data.Kind (Type) data U = U type family A (k :: Type) :: Type where A U = Type type family B (ty :: k) :: A k bad :: B 'U -> U bad _ = U }}} That gives the following panic when loaded in GHCi. {{{ ghc.exe: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-mingw32): kindPrimRep.go U }}} It does not panic when ''compiling'' with GHC. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12709#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler