[GHC] #14832: QuantifiedConstraints: Adding to the context causes failure

[GHC]

#14832: QuantifiedConstraints: Adding to the context causes failure
-------------------------------------+-------------------------------------
        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:                    |
-------------------------------------+-------------------------------------

Comment (by Iceland_jack):

 Is there hope for the user to guide this process and leaving the
 definition of `Trans` intact (not having to create `CCategory`)?

 If this were a rank-2 function we can explicitly instantiate `xx` `yy`
 `zz`

 {{{#!hs
 foo :: R X Y -> R Y Z -> (forall xx yy zz. (R xx yy, R yy zz) => R xx zz)
 -> R X Y
 foo xy yz f =
   f @X @Y @Z (xy, yz)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14832#comment:11>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler