#14520: GHC panic (TypeInType) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: TypeInType | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs {-# Language TypeInType, TypeFamilies, TypeOperators #-} import Data.Kind type a ~>> b = (a, b) -> Type data family Sing (a::k) type family (·) (f::a~>>b) (x::a)::b class PCategory kat where type Id ::kat·a·a type Comp::kat·b·c -> kat·a·b -> kat·a·c class SCategory kat where sId :: Sing a -> Sing (Id::kat a a) sComp :: Sing f -> Sing g -> Sing (Comp f g) }}} triggers a panic {{{ $ ghci -ignore-dot-ghci Bug.hs GHCi, version 8.3.20171122: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( Bug.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.3.20171122 for x86_64-unknown-linux): piResultTy k_a1KI[tau:1] a_a1vb[sk:1] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1147:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:951:35 in ghc:Type piResultTy, called at compiler/types/Type.hs:2309:34 in ghc:Type typeKind, called at compiler/types/Type.hs:2309:46 in ghc:Type typeKind, called at compiler/typecheck/TcType.hs:1706:11 in ghc:TcType Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14520 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler