[GHC] #14863: QuantifiedConstraints: Can't deduce `c' from `(a, b)' and `a |- b |- c'

[GHC]

#14863: QuantifiedConstraints: Can't deduce `c' from `(a, b)' and `a |- b |- c'
-------------------------------------+-------------------------------------
        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:
                                     |  QuantifiedConstraints wipT2893
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 In `uncurryC2` we have a given
 {{{
 [G] Implies a (Implies b c)
 }}}
 by taking its superclass we also have
 {{{
 [G] forall. a => Implies b c
 }}}
 But now we are stuck because I have not yet implemented the superclass
 story for quantified constraints.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14863#comment:2>
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