[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
      Resolution:                |             Keywords:
Operating System:  Windows       |         Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown  |            Test Case:
      Blocked By:                |             Blocking:
 Related Tickets:                |  Differential Rev(s):
       Wiki Page:                |
---------------------------------+----------------------------------------
Changes (by bgamari):

 * os:  Unknown/Multiple => Windows


Old description:

> 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)
> ```

New description:

 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)
 }}}

--

Comment:

 It seems there is some funniness around `printf` and MinGW. See `Note
 [Symbols for MinGW's printf]`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16387#comment:1>
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