[GHC] #14880: GHC panic: updateRole

[GHC]

#14880: GHC panic: updateRole
-------------------------------------+-------------------------------------
        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:                    |
-------------------------------------+-------------------------------------

Comment (by goldfire):

 I guess my "bake into `VarSet`" idea was essentially to take the `FV`
 module and combine it into the `VarSet` module, making clear that the FV-
 derived functions are the right way to incrementally build up a `VarSet`.
 It's kind of like we know to build up a `String` using higher-order
 functions, not `++` -- but we should make it very clear, right in the
 `VarSet` module.

 Going even further, I imagine this would generalize to any `Map` and might
 be good to incorporate into `containers`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:96>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler