[GHC] #11348: Local open type families instances ignored during type checking

[GHC]

#11348: Local open type families instances ignored during type checking
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        Reporter:  alexvieth         |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1-rc1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by alexvieth):

 Currently, we kind- and type-check `TyClGroup`s before we even consider
 any family instances. I suppose this is ok without `TypeInType`, where the
 kind of a type cannot depend upon a family instance. But with it, seems we
 have to check our `TyClGroup`s in tandem with our family instances! So the
 title of this ticket isn't so accurate; they're not ignored, they're just
 not considered until it's too late.

 The patch is no good. I believe I now understand the problem and I'm
 working on another patch.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11348#comment:1>
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