Re: [GHC] #10248: GHC panic when used with deferred type errors, again

2 May 2015


      #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:
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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

 }}}

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10248#comment:3
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