[GHC] #15852: Bad axiom produced for polykinded data family

[GHC]

#15852: Bad axiom produced for polykinded data family
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        Reporter:  goldfire          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.7
      Resolution:                    |             Keywords:  TypeFamilies,
                                     |  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 goldfire):

 My guess is that it is a pretty-printing bug, as if it were anything more
 serious would have been discovered by now.

 I would start by looking at `Coercion.pprCoAxiom`.

 Actually, better than just fixing this bug would be removing
 `Coercion.pprCoAxiom` in favor of the `IfaceAxiom` case of `pprIfaceDecl`.

 Unless it's not a pretty-printing bug.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15852#comment:1>
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