[GHC] #12797: Default Rules stop working when providing some constraints

[GHC]

#12797: Default Rules stop working when providing some constraints
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        Reporter:  danilo2           |                Owner:
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  GHC rejects       |            Test Case:
  valid program                      |  typecheck/should_compile/T12797
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by bgamari):

 * status:  merge => closed
 * resolution:   => fixed


Comment:

 Merged to `ghc-8.0` as 28c62bb588f7026d9985afe235cbeec5e3fd9a76.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12797#comment:8>
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