[GHC] #10635: -fwarn-redundant-constraints should not be part of -Wall

[GHC]

#10635: -fwarn-redundant-constraints should not be part of -Wall
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              Reporter:  Lemming     |             Owner:
                  Type:  feature     |            Status:  new
  request                            |         Milestone:
              Priority:  normal      |           Version:  7.11
             Component:  Compiler    |  Operating System:  Unknown/Multiple
  (Type checker)                     |   Type of failure:  Incorrect
              Keywords:              |  warning at compile-time
          Architecture:              |        Blocked By:
  Unknown/Multiple                   |   Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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 When I compile existing code with GHC-7.11.20150707 I get lot of
 "redundant constraints" warnings. Generally I think that this warning can
 be very useful for minimizing constraints, nonetheless there are good
 reasons not choose minimal constraints for a type signature.
 E.g. if I have to implement `Data.Map.singleton` I do not need the `Ord k`
 constraint for the key type. However, I might add it anyway in order to be
 able to change the implementation in future such that it uses `Ord k`
 dictionary.

 Thus I suggest to exclude `-fwarn-redundant-constraints` from `-Wall`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10635>
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