#13929: GHC panic with levity polymorphism ---------------------------------+-------------------------------------- Reporter: vagarenko | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 8.2.1-rc2 Resolution: | Keywords: TypeInType Operating System: Windows | Architecture: x86_64 (amd64) Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | ---------------------------------+-------------------------------------- Comment (by bgamari): For the record, a more complete callstack is, {{{ ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.2.0.20170704 for x86_64-unknown-linux): isUnliftedType GUnboxed g_a20x rg_a20y :: TYPE rg_a20y Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1954:10 in ghc:Type isUnliftedType, called at compiler/coreSyn/CoreUtils.hs:487:27 in ghc:CoreUtils needsCaseBinding, called at compiler/coreSyn/MkCore.hs:162:10 in ghc:MkCore mk_val_app, called at compiler/coreSyn/MkCore.hs:146:42 in ghc:MkCore mkCoreApps, called at compiler/coreSyn/MkCore.hs:154:26 in ghc:MkCore mkCoreConApps, called at compiler/coreSyn/MkCore.hs:364:5 in ghc:MkCore mkCoreUbxTup, called at compiler/coreSyn/MkCore.hs:370:32 in ghc:MkCore mkCoreTupBoxity, called at compiler/deSugar/DsExpr.hs:382:19 in ghc:DsExpr Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13929#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler