[GHC] #12890: Stdcall - treating as CCall (bogus warning on win 64 bit)

[GHC]

#12890: Stdcall - treating as CCall (bogus warning on win 64 bit)
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        Reporter:  tim-m89           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Windows           |         Architecture:  x86_64
 Type of failure:  Incorrect         |  (amd64)
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Phyx-):

 Hi,

 Thanks for the report.

 Win32 now contains a header you can include instead of needing to define
 the macros over and over again see
 https://github.com/haskell/win32/commit/7f91a92f74b7d93081df49d01b408ae1cd9c2ff9

 About the warning. While I agree, I don't know what the right thing here
 is. You most definitely should get a warning. But the Microsoft x64
 calling convention doesn't really have a name we can refer to. And the
 Haskell FFI standard doesn't allow you to omit the calling convention
 https://www.haskell.org/onlinereport/haskell2010/haskellch8.html#x15-1540008.4.

 We default to `cdecl` because that means in this case `do whatever is
 native to the platform`.

 If you have any suggestions on how we can do better here, I'm all for it!

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12890#comment:1>
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