[GHC] #11974: `default` declaration doesn't allow higher-kinded types

[GHC]

#11974: `default` declaration doesn't allow higher-kinded types
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        Reporter:  goldfire          |                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:  None/Unknown      |            Test Case:
                                     |  typecheck/should_compile/T11974,
                                     |  typecheck/should_fail/T11974b
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2136
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Fixing this seems to have (inadvertently?) changed the behavior of
 `ExtendedDefaultRules` in a subtle way in GHC 8.0.2. See #12907.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11974#comment:12>
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