[GHC] #11000: Implement `-Wcompat`

[GHC]

#11000: Implement `-Wcompat`
-------------------------------------+-------------------------------------
        Reporter:  hvr               |                Owner:  quchen
            Type:  feature request   |               Status:  patch
        Priority:  high              |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.10.2
      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:D1495
       Wiki Page:  Design/Warnings   |
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"6d147939628c8503d682ffbe2985ca435d7a7c1d/ghc" 6d14793/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="6d147939628c8503d682ffbe2985ca435d7a7c1d"
 Add -Wcompat warning flag group

 Reviewers: hvr, austin, thomie, bgamari

 Reviewed By: hvr, austin, thomie, bgamari

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D1495

 GHC Trac Issues: #11000
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11000#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler