[GHC] #13499: "Panic: no skolem info" with StaticPointers and typed hole

30 Mar 2017

      #13499: "Panic: no skolem info" with StaticPointers and typed hole
-------------------------------------+-------------------------------------
           Reporter:  Otini          |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Linux
  StaticPointers, hole, skolem,      |
  panic                              |
       Architecture:  x86_64         |   Type of failure:  Compile-time
  (amd64)                            |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 When compiling this minimal example:
 {{{#!hs
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE StaticPointers #-}

 import Data.Typeable (Typeable)
 import GHC.StaticPtr (StaticPtr)

 f :: Typeable a => StaticPtr (a -> a)
 f = static (\a -> _)

 main :: IO ()
 main = return ()
 }}}

 I get this output:

 {{{
 Bug.hs:8:19: error:ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.1 for x86_64-unknown-linux):
         No skolem info: a_aJo[sk]

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

 Unlike similar reported bugs, this happens on both 8.0.1 and 8.0.2.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13499
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