[GHC] #15798: Flag to warn when deriving strategy is not explicitly specified

[GHC]

#15798: Flag to warn when deriving strategy is not explicitly specified
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        Reporter:  andrewthad        |                Owner:  (none)
            Type:  feature request   |               Status:  closed
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.6.1
      Resolution:  fixed             |             Keywords:  deriving,
                                     |  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
                                     |  rename/should_compile/T15798{a,b,c}
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |  https://gitlab.haskell.org/ghc/ghc/merge_requests/48
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"c121e33f9b039acf2ac6939af8bfafe593560039/ghc"
 c121e33f/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="c121e33f9b039acf2ac6939af8bfafe593560039"
 Add -Wmissing-deriving-strategies

 Warn users when -XDerivingStrategies is enabled but not used, at each
 potential use site.

 add -Wmissing-deriving-strategies

 Reviewers: bgamari, RyanGlScott

 Subscribers: andrewthad, rwbarton, carter

 GHC Trac Issues: #15798

 Differential Revision: https://phabricator.haskell.org/D5451
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15798#comment:7>
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