#14175: Panic repSplitTyConApp_maybe -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.2.2 Component: Compiler (Type | Version: 8.2.1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #13910 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * cc: RyanGlScott (added) Comment: I suspect that this program (which panics after 0829821a6b886788a3ba6989e57e25a037bb6d05 on GHC HEAD) has the same underlying symptom: {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeFamilies #-} module Bug where class C k where data CD :: k -> k -> * instance C (Maybe a) where data CD :: (k -> *) -> (k -> *) -> * }}} {{{ $ inplace/bin/ghc-stage2 --interactive ../Bug.hs GHCi, version 8.3.20170818: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( ../Bug.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.3.20170818 for x86_64-unknown-linux): getRuntimeRep k_a1v3[sk:1] :: k_a1vl[tau:1] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1142:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1982:18 in ghc:Type }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14175#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler