[GHC] #12468: GADTs don't refine hole types

[GHC]

#12468: GADTs don't refine hole types
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        Reporter:  benjamin.hodgson  |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11325            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 On second thoughts, I don't think I'd fully realised that there was a type
 signature to guide the type checker.  Yes, it probably does make sense to
 "normalise" the hole with all the "givens". And it's very easy to do, a
 2-line change.  Patch coming

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12468#comment:6>
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