[GHC] #11370: Redundant superclass warnings being included in -Wall destroys the "3 Release Policy"

[GHC]

#11370: Redundant superclass warnings being included in -Wall destroys the "3
Release Policy"
-------------------------------------+-------------------------------------
        Reporter:  ekmett            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  7.10.3
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11369            |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by hvr):

 * cc: quchen (added)


Comment:

 NB: Currently `-Wredundant-constraints` is part of the default warning set
 (i.e. it's active even w/o `-W` or `-Wall`)

 (also, a tentative plan for GHC 8.2 is to overhaul the warning system to
 support warning-sets more uniformly, see also Design/Warnings)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11370#comment:4>
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