[GHC] #13158: Pattern synonyms should use type annotation information when typechecking

[GHC]

#13158: Pattern synonyms should use type annotation information when typechecking
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        Reporter:  lexi.lambda       |                Owner:
            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:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13159            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by goldfire):

 Your code looks reasonable to me and should be accepted. My guess is that
 this is just a type-checking bug, but I've not looked at the GHC code.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13158#comment:2>
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