[GHC] #11582: Redundant constraints warning complains that (a ~ b) is redundant

[GHC]

#11582: Redundant constraints warning complains that (a ~ b) is redundant
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  8.0.1-rc2
  checker)                           |
      Resolution:  invalid           |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by simonpj):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 I don't agree.  "Redundant" means that if you leave it off the function
 will still compile.  And indeed
 {{{
 asTypeOf1 :: a -> b -> a
 asTypeOf1 x _ = x
 }}}
 is just fine. So I don't know what you mean by saying "the type checker
 has gleaned something from it".

 I say it's behaving precisely as advertised, so I'll close as invalid. Re-
 open if I have misunderstood.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11582#comment:1>
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