[GHC] #7849: Error on pattern matching of an existential whose context includes a type function

[GHC]

#7849: Error on pattern matching of an existential whose context includes a type
function
-------------------------------------+-------------------------------------
              Reporter:  guest       |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:  7.10.1
             Component:  Compiler    |          Version:  7.4.2
  (Type checker)                     |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------
Changes (by thomie):

 * difficulty:   => Unknown
 * milestone:   => 7.10.1


Comment:

 With HEAD (ghc-7.9.20141121), the error message is still the same, except
 for these 2 extra lines:
 {{{
     Expected type: IO b0
       Actual type: IO ()
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7849#comment:2>
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