[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 simonpj):

 Re comment:83

 1. I think that `InterestingVarFun` is `const True`, so it only adds
 overhead.

 2. I think you mean that `NDFV` keeps a set of forall-bound variables, and
 checks in that set before adding to the accumulator.   But foralls are
 rare (I think), so the set will typically be empty.

 3.  That leaves the accumulator-style as the main candidate.

 As Richard says, though, the way to find out is to try it one thing at a
 time.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:84>
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