[GHC] #10742: GHC cannot deduce (irrelevant) reflexive type equality.

[GHC]

#10742: GHC cannot deduce (irrelevant) reflexive type equality.
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        Reporter:  ntc2              |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler (Type    |                 Version:  7.10.2
  checker)                           |                Keywords:  TypeLits
      Resolution:                    |  GADTs
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Changes (by thomie):

 * os:  Linux => Unknown/Multiple
 * architecture:  x86_64 (amd64) => Unknown/Multiple


Comment:

 Fwiw, ghc HEAD reports:
 {{{
 $ ghc-7.11.20150805 Test.hs
 [1 of 1] Compiling TypeLitsBug      ( Test.hs, Test.o )

 Test.hs:11:9: warning:
     Redundant constraints: ((x <=? y) ~ 'True, (y <=? z) ~ 'True)
     In the type signature for:
        test :: ((x <=? y) ~ 'True, (y <=? z) ~ 'True) => proxy x y z -> ()
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10742#comment:1>
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