[GHC] #14596: Remove uses of unsafeGlobalDynFlags for state hack

[GHC]

#14596: Remove uses of unsafeGlobalDynFlags for state hack
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4265
       Wiki Page:                    |
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Changes (by bgamari):

 * cc: DemiMarie (added)
 * differential:   => Phab:D4265


Comment:

 DemiMarie has a patch (Phab:D4265) implementing this. Unfortunately it's
 quite invasive.

 On the call Simon proposed an alternate way forward: rather than making
 the decision of whether to apply the state hack during simplification,
 instead push the decision up to the typechecker. The `State#` tycon would
 carry whether or not it should be considered for the state hack. Simonpj
 will likely pop up here and fill in more details later.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14596#comment:1>
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