[GHC] #13940: Reduce duplicate implementations of argument handling on Windows

[GHC]

#13940: Reduce duplicate implementations of argument handling on Windows
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           Reporter:  AndreasK          |             Owner:  (none)
               Type:  task              |            Status:  new
           Priority:  low               |         Milestone:
          Component:  Runtime System    |           Version:
           Keywords:  unicode windows   |  Operating System:  Windows
       Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
          Test Case:                    |        Blocked By:
           Blocking:                    |   Related Tickets:  #12870
Differential Rev(s):                    |         Wiki Page:
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 On windows we currently ignore arguments to hs_init/main's argv and
 instead get the arguments from the windows api when they are requested
 from the Haskell side.

 This means
 * Passing custom arguments to hs_init when not using hs_main might behave
 unexpected (The haskell und RTS side see different arguments).
 * Duplication of code to simulate filtering of Arguments by the RTS on the
 Haskell side.
 * Behavior between Linux and Windows might differ as result of the above
 (eg #13287)

 Instead we can get the UTF16 encoded arguments inside of hs_main from the
 windows API and pass them along to the RTS UTF8-encoded. This allows
 argument handling to be fairly uniform between Linux and Windows and
 enables us to accept hs_init arguments on Windows.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13940>
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