[GHC] #16232: Add setField to HasField

[GHC]

#16232: Add setField to HasField
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        Reporter:  adamgundry        |                Owner:  adamgundry
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.10.1
       Component:  Compiler (Type    |              Version:  8.7
  checker)                           |
      Resolution:                    |             Keywords:  ORF
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):

 You are right that does seem a bit tricky.

 Another possibility is generating renamed syntax when solving the
 constraint then type checking it and desugaring it using `tcExpr` and
 `dsExpr` to generate the necessary evidence? This is all possible to do in
 `ClsInst`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16232#comment:4>
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