[GHC] #9301: Rank-2 constraints are assigned kind *

[GHC]

#9301: Rank-2 constraints are assigned kind *
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        Reporter:  heisenbug         |            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 heisenbug):

 Running GHC with debug options `ghci -XRankNTypes -XConstraintKinds
 -ddump-parsed -ddump-rn -ddump-types -ddump-tcstrangelet.hs` I get:
 {{{
 ==================== Parser ====================
 strangelet :: forall t. Num t => ()
 strangelet = \ _ -> ()

 ==================== Renamer ====================
 Main.strangelet :: forall t. Num t => ()
 Main.strangelet = \ _ -> ()

 TYPE SIGNATURES
   strangelet :: (forall t. Num t) -> ()
 TYPE CONSTRUCTORS
 COERCION AXIOMS
 Dependent modules: []
 Dependent packages: [base, ghc-prim, integer-gmp]

 ==================== Typechecker ====================
 AbsBinds [] []
   {Exports: [strangelet <= strangelet
                <>]
    Exported types: strangelet :: (forall t. Num t) -> ()
                    [LclId, Str=DmdType]
    Binds: strangelet = \ _ -> GHC.Tuple.()}

 Ok, modules loaded: Main.
 }}}

 The renamer still has it right, while both `-ddump-types -ddump-tc`
 already show the wrong signature.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9301#comment:2>
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