[GHC] #11970: Simplify Parent for patten synonyms

[GHC]

#11970: Simplify Parent for patten synonyms
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        Reporter:  simonpj           |                Owner:  mpickering
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             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 simonpj):

 Replying to [comment:3 mpickering]:
 > I have looked a bit at this. The problem from last time is that when
 renaming exports we need to reject data constructors if they are exported
 with a type constructor which is not their parent.

 As I mention above, I think this would best be done in `tcExports`, which
 is where you reject pattern synonyms that are exported with a type
 constructor that is not their parent.

 Would that solve it?  I think it might make the `rnExport` code quite a
 bit simpler.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11970#comment:4>
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