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

[GHC]

#9230: Make -fwarn-tabs the default
-------------------------------+-------------------------------------------
        Reporter:  dfeuer      |            Owner:  jstolarek
            Type:  feature     |           Status:  new
  request                      |        Milestone:
        Priority:  normal      |          Version:  7.8.2
       Component:  Compiler    |         Keywords:
      Resolution:              |     Architecture:  Unknown/Multiple
Operating System:              |       Difficulty:  Easy (less than 1 hour)
  Unknown/Multiple             |       Blocked By:
 Type of failure:              |  Related Tickets:
  None/Unknown                 |
       Test Case:              |
        Blocking:              |
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Comment (by dfeuer):

 I looked into what making -fwarn-tabs the default would break in the GHC
 tree, and the answer appears to be "very little". It looks like the only
 files that use tabs for layout, use -Werror, and don't specify -fno-warn-
 tabs are libraries/time/Test/{ShowDST.hs,TimeZone.hs,CurrentTime.hs} and a
 test file that's designed to break from the tab warning. So contrary to
 some initial fears thoughtpolice raised in IRC, it will *not* be necessary
 to detab the whole GHC source to make this change.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9230#comment:4>
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