[GHC] #11364: Possible type-checker regression in GHC 8.0

[GHC]

#11364: Possible type-checker regression in GHC 8.0
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        Reporter:  hvr               |                Owner:
            Type:  bug               |               Status:  closed
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  7.10.3
  checker)                           |
      Resolution:  invalid           |             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 simonpj):

 You can make it compile by adding a signature to fix `e0` to be `ee`.  For
 example:
 {{{
 unthrow :: forall aa ee proxy. proxy ee -> (Throws ee => aa) -> aa
 unthrow _ x = unWrap (coerceWrap (Wrap x :: Wrap ee aa))
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11364#comment:5>
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