[GHC] #14880: GHC panic: updateRole

[GHC]

#14880: GHC panic: updateRole
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        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15076            |  Differential Rev(s):  Phab:D4769
       Wiki Page:                    |
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Comment (by goldfire):

 The next step would appear to be to duplicate the `FV` module (with
 identical function structure) but to drop the lists. Then use the new
 `NonDetFV` instead of `FV`. I would be shocked if the allocations go
 anywhere but down.

 Then, we'll have a new conundrum: why is `VarSet` slower than this
 `NonDetFV`? But let's not figure that out until we've made the observation
 that it is indeed slower.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:80>
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