[Bug 57888] New: Incorrect decimal fixed-point multiplication

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57888

Bug ID: 57888
           Summary: Incorrect decimal fixed-point multiplication
           Product: Wine
           Version: 10.0
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Sample code in .NET 4.8
-----------------------------
decimal x1 = 100m / 3m;
decimal x2 = 1.5m;
Console.WriteLine($"{x1} * {x2} = {x1 * x2}");
Console.WriteLine($"{x2} * {x1} = {x2 * x1}");
------------------------------
Output under Windows:
33,333333333333333333333333333 * 1,5 = 50,000000000000000000000000000
1,5 * 33,333333333333333333333333333 = 50,000000000000000000000000000
------------------------------
Output under WINE
33.333333333333333333333333333 * 1.5 = 50.000000000000000000000000000
1.5 * 33.333333333333333333333333333 = 2.4631024914413974438736297979
------------------------------

[Bug 57888] Incorrect decimal fixed-point multiplication

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57888

--- Comment #1 from Rafał Mużyło  ---
Is the output from wine produced with wine-mono or manually installed .NET 4.8
?

[Bug 57888] Incorrect decimal fixed-point multiplication

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57888

Sergey Isakov  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[e-mail]

--- Comment #2 from Sergey Isakov  ---
Can you upload this sample.exe to test?

[Bug 57888] Incorrect decimal fixed-point multiplication

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57888

--- Comment #3 from Alexander  ---
This is produced with manually installed .NET 4.8 (and other 4.x version) ?

[Bug 57888] Incorrect decimal fixed-point multiplication

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57888

--- Comment #4 from Alexander  ---
Created attachment 78147
  --> https://bugs.winehq.org/attachment.cgi?id=78147
Sample .exe to reproduce the bug

[Bug 57888] Incorrect decimal fixed-point multiplication

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57888

--- Comment #5 from Alexander  ---
This is produced with manually installed .NET 4.8 (and other 4.x version)

To multiple decimals, .NET Framework calls platfirm-specific internal unmanaged
function:

[SecurityCritical]
[MethodImpl(MethodImplOptions.InternalCall)]
private static extern void FCallMultiply(ref Decimal d1, ref Decimal d2);

IMHO, this bug is a result of incorrect processing of overflowing the
fractional part of the number with a fixed point after multiplication