[GHC] #9499: Add -prelude-is flag

[GHC]

#9499: Add -prelude-is flag
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              Reporter:  agibiansky  |            Owner:  agibiansky
                  Type:  feature     |           Status:  new
  request                            |        Milestone:
              Priority:  normal      |          Version:  7.9
             Component:  Compiler    |         Keywords:  flag
            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:D171   |
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Comment (by agibiansky):

 ezyang, if I implement this using the module renaming support, will that
 work if the new prelude `MyPrelude` isn't in a package? For example, if I
 just have two files named `A.hs` and `B.hs`, the current implementation
 allows you to write `ghc -prelude-is A B.hs` to use the module `A` as a
 prelude, even though you have no package structure at all.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9499#comment:5>
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