#14828: panic! when using :print on some functions with class constraints? -------------------------------------+------------------------------------- Reporter: jol | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.2.2 Resolution: | Keywords: debugger Operating System: Linux | Architecture: x86_64 Type of failure: Compile-time | (amd64) crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by olligobber): Note this is still an issue in 8.6.2 {{{ GHCi, version 8.6.2: http://www.haskell.org/ghc/ :? for help Prelude> :print fmap ghc: panic! (the 'impossible' happened) (GHC version 8.6.2 for x86_64-unknown-linux): isUnliftedType t1_a1x6[rt] :: TYPE t_a1x5[rt] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:2021:10 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14828#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler