[GHC] #12907: ExtendedDefaultRules-related regression in GHC 8.0.2

[GHC]

#12907: ExtendedDefaultRules-related regression in GHC 8.0.2
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        Reporter:  RyanGlScott       |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:  8.0.2
       Component:  Compiler (Type    |              Version:  8.0.2-rc1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2774
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"a452c6e57a286f3b31f0e3fbef83cbea0cee8b34/ghc"
 a452c6e5/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a452c6e57a286f3b31f0e3fbef83cbea0cee8b34"
 Make note of #12907 in 8.0.2 release notes

 Test Plan: Read it, commit it, merge it, ship it

 Reviewers: goldfire, bgamari, austin, hvr, simonpj

 Reviewed By: simonpj

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2774

 GHC Trac Issues: #12907
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12907#comment:5>
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