USING NIM TO GENERATE A DLL FOR USE IN C#/VB6-C#

main.nim

{.passc:"-m32"}
{.passl:"-m32"}
import winim,os

#nim c --cpu:i386 --app:lib --nomain
# https://www.appsloveworld.com/csharp/100/446/using-nim-to-generate-a-dll-for-use-in-c-vb6
proc TestFunc(a: cint):cint {.exportc, stdcall, dynlib.} =
    echo "function called!"
    a + 5

when defined(vcc):
    {.emit: "N_LIB_EXPORT N_CDECL(void, NimMain)(void);".}
else:
    proc NimMain() {.cdecl, importc.}

proc DllMain(hModule: HINSTANCE, reasonForCall: DWORD, lpReserved: LPVOID): WINBOOL {.exportc, dynlib, stdcall.} =
    case reasonForCall:
    of DLL_PROCESS_ATTACH:
        when defined(vcc):
            {.emit: "NimMain();".}
        else:
            NimMain()
        AllocConsole()
        discard stdout.reopen("CONOUT$", fmWrite)
        discard execShellCmd("chcp 65001")
        echo "Hello from Nim Code!"

    else:
        discard
    return TRUE

main.vb

Private Declare Function TestFunc Lib "nim.dll" Alias "TestFunc@4" (ByVal a As Long) As Long

Private Sub Form_Load()
    Caption = CStr(TestFunc(5))
End Sub