[GHC] #14128: Possible bug in Renamer when dealing with orphans

[GHC]

#14128: Possible bug in Renamer when dealing with orphans
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        Reporter:  Shayan-Najd       |                Owner:  bgamari
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.2.2
       Component:  Compiler (Type    |              Version:  8.2.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3892
       Wiki Page:                    |
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Changes (by simonpj):

 * cc: ezyang (added)


Comment:

 Edward is the expert here.  Edward: might you look at Ben's proposed fix?
 If correct, it needs a careful Note along the lines of the Summary of
 Phab:D3892.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14128#comment:12>
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