[GHC] #15591: Inconsistent kind variable binder visibility between associated and non-associated type families

[GHC]

#15591: Inconsistent kind variable binder visibility between associated and non-
associated type families
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:
                                     |  TypeApplications, TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15592            |  Differential Rev(s):  Phab:D5159
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by RyanGlScott):

 * status:  new => patch
 * differential:   => Phab:D5159


Comment:

 By gum, I think I figured out this one. The trick was to pass the type
 variables bound by the class directly `kcLHsQTyVars` and to use that to
 one's advantage. See Phab:D5159.

 I still haven't figured out how to make the non-CUSK case for
 `kcLHsQTyVars` work yet (that code confuses the bejeezus out of me), but
 that's the topic of a separate ticket (#15592) anyway, so I'll leave that
 for later.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15591#comment:11>
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