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Opened by Icelandjack@IcelandjackReporter

GHC panic when used with deferred type errors, again

Similar to previous report of mine #9834 (closed). Given error.hs

data I a = I a

I get the following result:

$ 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>
Edited by Icelandjack