[GHC] #14331: Overzealous free-floating kind check causes deriving clause to be rejected

[GHC]

#14331: Overzealous free-floating kind check causes deriving clause to be rejected
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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:  deriving
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 I meant exactly what I wrote in the original description: it should emit:

 {{{#!hs
 instance C (a :: k) D
 }}}

 After all, the user wrote `deriving (C (a :: k))`, and the data type is
 `D`. What you get after doing the whole `deriving` macro-application-eta-
 reduction-kind-unification shebang is `C (a :: k) D`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14331#comment:5>
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