[GHC] #14579: GeneralizedNewtypeDeriving produces ambiguously-kinded code

[GHC]

#14579: GeneralizedNewtypeDeriving produces ambiguously-kinded code
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.10.1
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  deriving
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  GHC rejects       |            Test Case:
  valid program                      |  deriving/should_compile/T14579{a}
      Blocked By:  12045             |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4264,
       Wiki Page:                    |  Phab:D5229
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Comment (by simonpj):

 > I was originally hopeful that we could avoid generating any explicit
 kind signatures and exclusively use visible kind application.

 Yes I agree with your analysis.  Visible kind application (VKA) can only
 be used for Specified arguments, and user-defined types can have Inferred
 arguments.  So yes, if there are no Inferred ones (a common case) you can
 use VKA; but not if not.  Annoying!

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14579#comment:22>
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