#13819: TypeApplications-related GHC panic -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler (Type | Version: 8.2.1-rc2 checker) | Keywords: Resolution: | TypeApplications Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #13846, #13850 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * related: => #13846, #13850 Comment: Two more ways to trigger this panic: * #13846: {{{ $ ghci -XTypeApplications -ignore-dot-ghci GHCi, version 8.3.20170605: http://www.haskell.org/ghc/ :? for help Prelude> :t fmap @(_ -> _) ghc: panic! (the 'impossible' happened) (GHC version 8.3.20170605 for x86_64-unknown-linux): repSplitAppTys w0_a1pF[tau:2] w0_a1pH[tau:2] [] 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:809:9 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} * #13850 {{{
cat wibble.hs ecase :: Either a b -> (a -> c) (b -> c) -> c ecase (Left a) f _ = f a ecase (Right b) _ g = g b
ghci wibble.hs GHCi, version 8.2.0.20170507: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/erikd/.ghci [1 of 1] Compiling Main ( wibble.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.2.0.20170507 for x86_64-unknown-linux): repSplitAppTys a_a1pA[sk:1] c_a1pC[sk:1] [] Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1134:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1138:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:808:9 in ghc:Type }}}
Both of these were also caused by b207b536ded40156f9adb168565ca78e1eef2c74. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13819#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler