#15597: GHC shouting: panic! -------------------------------------+------------------------------------- Reporter: tstr | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.1 Keywords: TypeInType | Operating System: Linux Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This program makes the impossible happen: {{{#!hs {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeInType #-} import GHC.Types data Bug :: (f x -> Type) -> Type where Bug :: forall (r::h -> forall x. f x -> Type) (a::f x) . (r::((f x -> Type) -> Type) -> forall x. f x -> Type) Bug a -> Bug (r::f x -> Type) }}} And asked for reporting the error: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.4.1 for x86_64-unknown-linux): piResultTy k_aozeA[tau:1] (x_aozeN[sk:2] |> {co_aozeO}) Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:950:35 in ghc:Type }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15597 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler