[GHC] #14401: Add a test ensuring that TypeReps can be stored in compact regions

[GHC]

#14401: Add a test ensuring that TypeReps can be stored in compact regions
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           Reporter:  dfeuer         |             Owner:  (none)
               Type:  task           |            Status:  new
           Priority:  normal         |         Milestone:  8.2.2
          Component:  Test Suite     |           Version:  8.2.1
           Keywords:  Typeable       |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 My work thus far on Phab:D4085 has involved `TypeRep`s with cyclical
 structure. That bit me in `break011` and `break024` because `:force`
 doesn't work with cyclical structures. This would also have caused trouble
 for storing `TypeRep`s in compact regions. If we eventually make `:force`
 work with cyclical structures (see #14400), then cyclical `TypeRep`s won't
 break the test suite but might break user code using compact regions. So
 let's test for that.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14401>
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