#13202: Levity polymorphism panic in GHCi -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.2.1 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 adamgundry): I've just seen this as well, in a different context: {{{ GHCi, version 8.1.20170217: http://www.haskell.org/ghc/ :? for help Prelude> import GHC.Records Prelude GHC.Records> :set -XTypeApplications -XDataKinds Prelude GHC.Records> let foo = getField @"name" ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20170217 for x86_64-unknown-linux): isUnliftedType forall (a :: TYPE q). a :: TYPE q Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1197:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1201:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1889:10 in ghc:Type isUnliftedType, called at compiler/typecheck/TcRnDriver.hs:1822:32 in ghc:TcRnDriver Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13202#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler