[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:
       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):

 > So far, a naive attempt at rewriting tcvs_of_type in terms of VarSet ->
 VarSet didn't produce significant performance improvements

 What does the naive attempt look like.  I'm expecting:
 {{{
 tcvs_of_type :: Type -> VarSet -> VarSet
 tcvs_of_type (App t1 t2) acc = tcvs_of_type t1 (tcvs_of_type t2 acc)
 ...etc...
 }}}
 Is that what you have?

 I would not worry about foralls -- they are relatively rare.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:51>
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