[GHC] #9196: Higher-rank constraint treated as type instead

[GHC]

#9196: Higher-rank constraint treated as type instead
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        Reporter:  goldfire          |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by archblob):

 Experimenting with this I found that ghc will go along with `foo :: a ->
 ((forall b. P b) => b) -> a` and transform it in `foo :: a -> ((forall b.
 P b) -> b) -> a`.
 I may have a simple fix for this, just a check for foralls when
 typechecking a context.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9196#comment:2>
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