[GHC] #11405: Incorrect failure of type-level skolem escape check

[GHC]

#11405: Incorrect failure of type-level skolem escape check
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        Reporter:  goldfire          |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  8.0.1-rc1
      Resolution:                    |             Keywords:  TypeInType
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 goldfire):

 I agree that we can fix this one problem, but I doubt that it would
 generalize. I'd like to understand better what's going on here before
 going down that route.

 See NoSubKinds (Issues from Dimitrios) for more information about levity-
 polymorphic binders. The short answer is that we need to know the runtime
 size of binders, and we don't know this for levity-polymorphic ones.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11405#comment:6>
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