[GHC] #16195: Program with trivial polymorphism leads to out of scope dictionary

[GHC]

#16195: Program with trivial polymorphism leads to out of scope dictionary
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        Reporter:  mpickering        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.7
      Resolution:                    |             Keywords:
                                     |  TypedTemplateHaskell
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 mpickering):

 I tried adding a call to `captureTopConstraints` around the `zonkTcGblEnv`
 where the splices are run but it doesn't seem to capture any evidence.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16195#comment:1>
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