[GHC] #15278: Add -Werror=compat, enable it in the testsuite

[GHC]

#15278: Add -Werror=compat, enable it in the testsuite
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        Reporter:  int-index         |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"04e9fe5c7d3c2bac46933e3d647e561cb741edf4/ghc" 04e9fe5/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="04e9fe5c7d3c2bac46933e3d647e561cb741edf4"
 Add -Werror=compat

 Add a flag `-Werror=compat` to GHC which has the effect of `-Werror=x
 -Werror=y ...`, where `x, y, ...` are warnings from the `-Wcompat`
 option group.

 Test Plan: ./validate

 Reviewers: bgamari

 Reviewed By: bgamari

 Subscribers: rwbarton, thomie, carter

 GHC Trac Issues: #15278

 Differential Revision: https://phabricator.haskell.org/D4860
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15278#comment:2>
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