[GHC] #9316: GHC 7.8.3 no longer infers correct type in presence of type families and constraints

[GHC]

#9316: GHC 7.8.3 no longer infers correct type in presence of type families and
constraints
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              Reporter:  ocharles    |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:
             Component:  Compiler    |           Version:  7.8.3
            Resolution:              |          Keywords:
Differential Revisions:              |  Operating System:  Unknown/Multiple
          Architecture:              |   Type of failure:  None/Unknown
  Unknown/Multiple                   |         Test Case:
            Difficulty:  Unknown     |          Blocking:
            Blocked By:              |
       Related Tickets:              |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"4b3df0bb705c9287046c07bbc6c038960fbf8d53/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="4b3df0bb705c9287046c07bbc6c038960fbf8d53"
 Further improvements to floating equalities

 This equality-floating stuff is horribly delicate!  Trac #9316 showed
 up yet another corner case.

 The main changes are
  * include CTyVarEqs when "growing" the skolem set
  * do not include the kind argument to (~) when growing the skolem set

 I added a lot more comments as well
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9316#comment:1>
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