[GHC] #15795: Core lint error with unused kind variable in data type return kind

[GHC]

#15795: Core lint error with unused kind variable in data type return kind
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:  TypeInType
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 Simon Peyton Jones <simonpj@…>):

 In [changeset:"71e26a74da5e5e9a61163b87ab4d22de88a2d04a/ghc"
 71e26a74/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="71e26a74da5e5e9a61163b87ab4d22de88a2d04a"
 Make candidateQTvs contain tyvar with zonked kinds

 candidateQTyVars was failing to return fully-zonked
 tyvars, and that made things fall over chaotically
 when we try to sort them into a well-scoped telescope.
 Result: Trac #15795

 So I made candidateQTvs guarantee to have fully-zonked
 tyvars (i.e. with zonked kinds).  That's a bit annoying
 but not really difficult.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15795#comment:6>
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