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

[GHC]

#9230: Make -fwarn-tabs the default
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              Reporter:  dfeuer      |            Owner:  mlen
                  Type:  feature     |           Status:  closed
  request                            |        Milestone:  7.10.1
              Priority:  normal      |          Version:  7.8.2
             Component:  Compiler    |         Keywords:
            Resolution:  fixed       |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Easy (less than 1
  Unknown/Multiple                   |  hour)
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:  Phab:D255,  |
  Phab:D399                          |
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Comment (by Polarina):

 Tabs are generally not the cause for incorrect indentation. It is mixing
 them with spaces that do.

 An alternative approach would be to warn if a tab character is preceded by
 a space. That would keep the tabs people happy, even those that use tabs
 for indentation and spaces for alignment; while catching most cases of
 tab/space mix-ups.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9230#comment:30>
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