[GHC] #2159: Use a more efficient representation than [DynFlag]

[GHC]

#2159: Use a more efficient representation than [DynFlag]
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        Reporter:  igloo             |                Owner:
            Type:  bug               |               Status:  closed
        Priority:  lowest            |            Milestone:
       Component:  Compiler          |              Version:  6.8.2
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by bgamari):

 * status:  new => closed
 * resolution:   => fixed


Comment:

 Unless I am mistaken this has already been implemented. `DynFlags` now
 represents dump flags, extension flags, and general flags as `IntSet`s,
 using the `Enum` instances of the respective types to map each flag to a
 bit. I'm not entirely sure when this change was made but it was quite a
 while ago.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2159#comment:20>
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