[GHC] #12959: GHC doesn't warn about missing implementations for class methods beginning with an underscore

[GHC]

#12959: GHC doesn't warn about missing implementations for class methods beginning
with an underscore
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        Reporter:  RyanGlScott       |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2849
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"503219e3e1667ac39607021b2d9586260fbab32b/ghc" 503219e/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="503219e3e1667ac39607021b2d9586260fbab32b"
 Warn about missing instance methods that start with an underscore

 Previously, GHC would not warn whenever there was a class instance that
 didn't implement a class method whose name begins with an underscore.

 Fixes #12959.

 Test Plan: make test TEST=WarnMinimal

 Reviewers: austin, bgamari, simonpj

 Reviewed By: bgamari, simonpj

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2849

 GHC Trac Issues: #12959
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12959#comment:8>
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