[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:  new
  request                            |        Milestone:
              Priority:  normal      |          Version:  7.8.2
             Component:  Compiler    |         Keywords:
            Resolution:              |     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:              |
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Comment (by mlen):

 The main patch can be found here:
 https://github.com/mlen/ghc/commit/62cd7b983aee6b581f42184fcc38b3d9bf50780e,
 while this commit includes only additions of -fno-warn-tabs:
 https://github.com/mlen/ghc/commit/1c60eaffe373bf6a6324d1a243130b9dbbf843b5
 I still need to take care of submodules.
 libraries/{haskeline,hpc,stm,time,unix,xhtml} and utils/hsc2hs need to be
 patched because of -Werror.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9230#comment:8>
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