[GHC] #13951: InScope set assertion failure from monad-skeleton

[GHC]

#13951: InScope set assertion failure from monad-skeleton
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        Reporter:  mpickering        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by monoidal):

 I've reduced to:

 {{{
 #!hs
 {-# LANGUAGE PolyKinds, Rank2Types #-}
 module T13951 where

 viewL :: forall k. Bool -> (forall x. k x -> Int) -> Int
 viewL False _ = 0
 viewL True  r = r undefined
 }}}

 (note this is now a warning, not an assertion failure)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13951#comment:1>
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