[GHC] #16191: GHC Panic deriving unbox vector (StrictData/unbox-strict-fields interaction)

[GHC]

#16191: GHC Panic deriving unbox vector (StrictData/unbox-strict-fields
interaction)
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        Reporter:  dbeacham          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 That looks bad.

 Is it possible to repro this without relying on vector?  And without TH?
 Perhaps by writing out the code that TH generates?

 Could it be #15523? Does it happen in HEAD?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16191#comment:2>
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