[GHC] #12927: Colorized error messages result in hard-to-read .dump-* files

[GHC]

#12927: Colorized error messages result in hard-to-read .dump-* files
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        Reporter:  RyanGlScott       |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #8809             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Rufflewind):

 Another workaround would be to pass `-fdiagnostics-color=never` to ghc.

 I think the right fix would be to not output ANSI color codes except when
 the destination is stderr.  It's a bit tricky though because I'm not sure
 how to detect this from within `mkLocMessageAnn`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12927#comment:2>
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