[GHC] #13885: Template Haskell doesn't freshen GADT type variables properly

[GHC]

#13885: Template Haskell doesn't freshen GADT type variables properly
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Template Haskell  |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:  th/T13885
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3867
       Wiki Page:                    |
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Changes (by RyanGlScott):

 * status:  closed => new
 * resolution:  fixed =>


Comment:

 As I discovered in https://phabricator.haskell.org/D3867#108979, there's
 some cases that Phab:D3867 missed. Reopening.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13885#comment:8>
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