[GHC] #9056: --make paths are not deduplicated

[GHC]

#9056: --make paths are not deduplicated
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        Reporter:  evincarofautumn   |                   Owner:
            Type:  feature request   |                  Status:  closed
        Priority:  normal            |               Milestone:
       Component:  Driver            |                 Version:  7.8.2
      Resolution:  wontfix           |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by rwbarton):

 I generally agree with thomie here, but I think there is some room for
 interpretation since ghc's make mode already is a bit "do what I mean".
 For example, if module A imports module B, then `ghc A.hs B.hs` does the
 same as `ghc A.hs`, so there seems to be some kind of deduplication
 happening already.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9056#comment:4>
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