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

[GHC]

#9230: Make -fwarn-tabs the default
-------------------------------------+-------------------------------------
              Reporter:  dfeuer      |            Owner:  mlen
                  Type:  feature     |           Status:  patch
  request                            |        Milestone:  7.10.1
              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:  Phab:D255,  |
  Phab:D399                          |
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Comment (by Austin Seipp <austin@…>):

 In [changeset:"c6d4ae6f437fb041ea70f3d2b4f7f0d03ff797bf/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="c6d4ae6f437fb041ea70f3d2b4f7f0d03ff797bf"
 Fix test driver python3 compatibility issues

 Summary:
 Fixes python3 compatibility issues by replacing filter with a list
 comperhension and a potential issue with python2 when override_flags
 would be an empty list.

 Reviewers: austin, thomie

 Reviewed By: austin, thomie

 Subscribers: thomie, carter, simonmar, mlen

 Differential Revision: https://phabricator.haskell.org/D399

 GHC Trac Issues: #9230
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9230#comment:28>
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