#10248: GHC panic when used with deferred type errors, again ---------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.10.1-rc3 Resolution: | Keywords: Operating System: Linux | Architecture: x86 Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: ---------------------------------+------------------------------------- Description changed by Iceland_jack: Old description:

Similar to previous report of mine #9834. Given `error.hs` {{{#!hs data I a = I a }}}

I get the following result: {{{#!hs $ ghci -fdefer-type-errors -ignore-dot-ghci error.hs http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( error.hs, interpreted ) Ok, modules loaded: Main. *Main> I <$> _ I <$> _

<interactive>:2:7: Warning: Found hole ‘_’ with type: IO a0 Where: ‘a0’ is an ambiguous type variable In the second argument of ‘(<$>)’, namely ‘_’ In the first argument of ‘GHC.GHCi.ghciStepIO :: IO a_auR -> IO a_auR’, namely ‘I <$> _’ In a stmt of an interactive GHCi command: it <- GHC.GHCi.ghciStepIO :: IO a_auR -> IO a_auR (I <$> _) ghc: panic! (the 'impossible' happened) (GHC version 7.10.0.20150316 for i386-unknown-linux): nameModule $dShow_aIT

Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug

*Main> }}}

New description: Similar to previous report of mine #9834. Given `error.hs` {{{#!hs data I a = I a }}} I get the following result: {{{#!hs $ ghci -fdefer-type-errors -ignore-dot-ghci error.hs GHCi, version 7.10.0.20150316: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( error.hs, interpreted ) Ok, modules loaded: Main. *Main> I <$> _ I <$> _ <interactive>:2:7: Warning: Found hole ‘_’ with type: IO a0 Where: ‘a0’ is an ambiguous type variable In the second argument of ‘(<$>)’, namely ‘_’ In the first argument of ‘GHC.GHCi.ghciStepIO :: IO a_auR -> IO a_auR’, namely ‘I <$> _’ In a stmt of an interactive GHCi command: it <- GHC.GHCi.ghciStepIO :: IO a_auR -> IO a_auR (I <$> _) ghc: panic! (the 'impossible' happened) (GHC version 7.10.0.20150316 for i386-unknown-linux): nameModule $dShow_aIT Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug *Main> }}} -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10248#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10248: GHC panic when used with deferred type errors, again ---------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.10.1-rc3 Resolution: | Keywords: Operating System: Linux | Architecture: x86 Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: ---------------------------------+------------------------------------- Comment (by ion1): I encountered the following on GHC 7.10.1, looks like it might be the same bug: {{{ % ghc -ignore-dot-ghci -fdefer-typed-holes -e 'map (\a b -> undefined) _' <interactive>:1:25: Warning: Found hole ‘_’ with type: [a0] Where: ‘a0’ is an ambiguous type variable Relevant bindings include it :: [t -> t1] (bound at <interactive>:1:1) In the second argument of ‘map’, namely ‘_’ In the expression: map (\ a b -> undefined) _ In an equation for ‘it’: it = map (\ a b -> undefined) _ <interactive>:1:25: Warning: Found hole ‘_’ with type: [a0] Where: ‘a0’ is an ambiguous type variable Relevant bindings include it :: [t -> t2] (bound at <interactive>:1:1) In the second argument of ‘map’, namely ‘_’ In the expression: map (\ a b -> undefined) _ In an equation for ‘it’: it = map (\ a b -> undefined) _ <interactive>: <interactive>: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): nameModule $dShow_aMc Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10248#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10248: GHC panic when used with deferred type errors, again ---------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: GHCi | Version: 7.10.1-rc3 Resolution: fixed | Keywords: Operating System: Linux | Architecture: x86 Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: ---------------------------------+------------------------------------- Changes (by simonpj): * status: new => closed * resolution: => fixed Comment: Seems ok in 7.10 too -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10248#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10248: GHC panic when used with deferred type errors, again ---------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: GHCi | Version: 7.10.1-rc3 Resolution: fixed | Keywords: Operating System: Linux | Architecture: x86 Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: ---------------------------------+------------------------------------- Comment (by Simon Peyton Jones ): In [changeset:"fa0bdd3d6e1fa7bca044ee13b84f6aeeacbe50e2/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="fa0bdd3d6e1fa7bca044ee13b84f6aeeacbe50e2" Test Trac #10248 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10248#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler