[GHC] #16263: GHC accepts illegal constraint in kind

[GHC]

#16263: GHC accepts illegal constraint in kind
-------------------------------------+-------------------------------------
           Reporter:  goldfire       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.6.3
           Keywords:  TypeInType     |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 GHC 8.6 accepts

 {{{#!hs
 data Q :: Eq a => Type
 }}}

 It shouldn't, as we can't have `Eq a` as a constraint in kinds. Note that
 writing a constructor for `Q` is rejected.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16263>
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