[GHC] #16381: Regression: Implicitly kind variables not in scope

[GHC]

#16381: Regression: Implicitly kind variables not in scope
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  highest           |            Milestone:  8.10.1
       Component:  Compiler (Type    |              Version:  8.9
  checker)                           |
      Resolution:  invalid           |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 See also
 https://github.com/hvr/head.hackage/commit/8db44df47e6ca07ea2f8140dfa672d0f9f542ac7,
 which patches `singleton-bool` in the upstream `head.hackage` repo.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16381#comment:2>
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