[GHC] #11099: Incorrect warning about redundant constraints

[GHC]

#11099: Incorrect warning about redundant constraints
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        Reporter:  diatchki          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.11
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by rwbarton):

 I think redundant here means basically: the definition of `f` would be
 accepted without the constraint. It doesn't mean that the type of `f`
 would be the same if you removed the constraint. The idea is to catch
 constraints that aren't actually used in the function, so that you could
 make the type of the function more general.

 In that case the constraint really is redundant, right?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11099#comment:1>
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