[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:                    |
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Comment (by RyanGlScott):

 Using the latest commit on the `wip/T2893` branch, this program now gives
 you a stack overflow!

 {{{
 $ inplace/bin/ghc-stage2 --interactive ../Bug.hs
 GHCi, version 8.5.20180128: http://www.haskell.org/ghc/  :? for help
 Loaded GHCi configuration from /home/rgscott/.ghci
 [1 of 1] Compiling Main             ( ../Bug.hs, interpreted )

 ../Bug.hs:15:10: error:
     • Reduction stack overflow; size = 201
       When simplifying the following type: rel xx yy0
       Use -freduction-depth=0 to disable this check
       (any upper bound you could choose might fail unpredictably with
        minor updates to GHC, so disabling the check is recommended if
        you're sure that type checking should terminate)
     • In the instance declaration for ‘Category (With rel)’
    |
 15 | instance (Refl rel, Trans rel) => Category (With rel) where
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14832#comment:5>
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