[GHC] #11000: Implement `-Wcompat`

[GHC]

#11000: Implement `-Wcompat`
-------------------------------------+-------------------------------------
        Reporter:  hvr               |                Owner:  quchen
            Type:  feature request   |               Status:  new
        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   |
-------------------------------------+-------------------------------------
Changes (by hvr):

 * owner:   => quchen
 * differential:   => Phab:D1495


--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11000#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler