[GHC] #9230: Make -fwarn-tabs the default

[GHC]

#9230: Make -fwarn-tabs the default
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        Reporter:  dfeuer            |                   Owner:  mlen
            Type:  feature request   |                  Status:  closed
        Priority:  normal            |               Milestone:  7.10.1
       Component:  Compiler          |                 Version:  7.8.2
      Resolution:  fixed             |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:  Phab:D255,
                                     |  Phab:D399
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Comment (by beroal):

 What about people who use tab characters for indentation regularly? My
 code looks correct for any tab character width chosen.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9230#comment:33>
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