#14040: Typed holes regression in GHC 8.0.2: No skolem info: z_a1sY[sk:2] -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.2 checker) | Keywords: TypeInType, Resolution: | TypeFamilies, | PartialTypeSignatures, TypedHoles Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #13877 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Here is a much simpler way to trigger the panic in comment:2: {{{#!hs {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeInType #-} module Bug where import Data.Kind import Data.Proxy newtype S (f :: k1 -> k2) = MkS (forall t. Proxy t -> Proxy (f t)) foo :: forall (a :: Type) (f :: forall (x :: a). Proxy x -> Type). S f -> () foo (MkS (sF :: _)) = () }}} {{{ $ ~/Software/ghc/inplace/bin/ghc-stage2 --interactive Bug.hs GHCi, version 8.5.20180420: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:15:17: error:ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.5.20180420 for x86_64-unknown-linux): No skolem info: [a1_a1Cb[sk:1]] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1162:37 in ghc:Outputable pprPanic, called at compiler/typecheck/TcErrors.hs:3224:5 in ghc:TcErrors }}} But it now appears that this bug is of a different nature than the original program. I'll close this ticket in favor of a new one. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14040#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler