[GHC] #14198: Inconsistent treatment of implicitly bound kind variables as free-floating

[GHC]

#14198: Inconsistent treatment of implicitly bound kind variables as free-floating
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #7873             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Going with option 1 (have both be an error) sounds fine to me. But I'm not
 quite sure what the error message should be when we encounter an inferred,
 free-floating kind variable, as in `data Foo = MkFoo (forall a. Proxy a)`,
 where the `k` in `(a :: k)` is inferred. We could go with the usual `Kind
 variable ‘k’ is implicitly bound in data type` fare, but users might find
 that befuddling.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14198#comment:3>
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