[GHC] #10752: Print which warning-flag controls/enabled an emitted warning

[GHC]

#10752: Print which warning-flag controls/enabled an emitted warning
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        Reporter:  hvr               |                Owner:  barrucadu
            Type:  feature request   |               Status:  closed
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1943
       Wiki Page:  Design/Warnings   |
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Comment (by Thomas Miedema <thomasmiedema@…>):

 In [changeset:"f8a5dd05ed50fe46eb86f30dc12f4c341b980e61/ghc"
 f8a5dd05/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="f8a5dd05ed50fe46eb86f30dc12f4c341b980e61"
 Only add -fshow-warning-groups for ghc >= 7.11 (#10752)
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10752#comment:23>
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