[GHC] #9288: Type class overlapping instances check doesn't understand type equality

[GHC]

#9288: Type class overlapping instances check doesn't understand type equality
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              Reporter:  ezyang      |             Owner:
                  Type:  bug         |            Status:  closed
              Priority:  low         |         Milestone:
             Component:  Compiler    |           Version:  7.9
  (Type checker)                     |          Keywords:
            Resolution:  invalid     |  Operating System:  Unknown/Multiple
Differential Revisions:              |   Type of failure:  GHC accepts
          Architecture:              |  invalid program
  Unknown/Multiple                   |         Test Case:
            Difficulty:  Unknown     |          Blocking:
            Blocked By:              |
       Related Tickets:              |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"0fcf060418167e05adfbde174b2f030077cb1c1b/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="0fcf060418167e05adfbde174b2f030077cb1c1b"
 Improve documentation of overlapping instances (again)

 Prompted by Trac #9288
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9288#comment:4>
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