[GHC] #13128: Refactor AvailInfo to be more sensible

[GHC]

#13128: Refactor AvailInfo to be more sensible
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        Reporter:  mpickering        |                Owner:  mpickering
            Type:  task              |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:  12662
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 > `AvailInfo` has been the bane of my life for the last 12 months and I
 want to tame it.

 I'm all for making things better!  But while both (1) and (2) are valid
 complaints, but neither quite justifies "bane".  Have you been hammered
 with efficiency problems from (2)?  Has (1) really bitten you?  Can you
 point to code that it painful as a result?

 > The next plan of attack is to distinguish between `IfaceAvailInfo` and
 `AvailInfo`.

 That makes sense to me.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13128#comment:2>
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