[GHC] #4426: Simplify the rules for implicit quantification

[GHC]

#4426: Simplify the rules for implicit quantification
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              Reporter:  simonpj     |            Owner:
                  Type:  feature     |           Status:  new
  request                            |        Milestone:  7.10.1
              Priority:  highest     |          Version:  6.12.3
             Component:  Compiler    |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:  #7880
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:  Phab:D211   |
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Comment (by goldfire):

 I'm very late to this conversation, so please ignore me if this is silly.

 Why not just jump the gun and make this an error right now? Has anyone
 tried to see how many packages on Hackage this would break? Spreading the
 effects of this change over 3 releases (warning in 7.10, error in 7.12
 while deprecating the warning flag, remove warning flag in 7.14) seems
 like a lot of overhead when the amount of affected code is (in my
 uneducated guess) very small.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4426#comment:18>
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