[GHC] #11762: GHC 8 superclass chain constraint regression

[GHC]

#11762: GHC 8 superclass chain constraint regression
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        Reporter:  _deepfire         |                Owner:
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  8.0.1-rc2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11427            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by _deepfire):

 Oh my god, does it mean we are going to sacrifice the very convenient,
 simple and obvious (for some value of "simple" and "obvious") implication
 on the altar of recursive superclasses?

 Because #11427 seems to conclude in that way..

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11762#comment:4>
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