[GHC] #16387: Duplicate vsnwprintf symbol on Windows

[GHC]

#16387: Duplicate vsnwprintf symbol on Windows
-------------------------------------+-------------------------------------
           Reporter:  bgamari        |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.6.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Leading to failure of `T5836`:

 ```
 Stderr ( T5836 ):
 GHC runtime linker: fatal error: I found a duplicate definition for symbol
    __mingw_vsnwprintf
 whilst processing object file
 C:\GitLabRunner\builds\8fc0e283\0\ghc\ghc\inplace\mingw\x86_64-w64-mingw32\lib\libmingwex.a
 The symbol was previously defined in
    (GHCi built-in symbols)
 This could be caused by:
    * Loading two different object files which export the same symbol
    * Specifying the same object file twice on the GHCi command line
    * An incorrect `package.conf' entry, causing some object to be
      loaded twice.
 ghc-stage2.exe: panic! (the 'impossible' happened)
   (GHC version 8.9.20190303 for x86_64-unknown-mingw32):
         loadArchive
 "C:\\GitLabRunner\\builds\\8fc0e283\\0\\ghc\\ghc\\inplace\\mingw\\x86_64-w64-mingw32\\lib\\libmingwex.a":
 failed

 Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug
 *** unexpected failure for T5836(ghci)
 ```

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16387>
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