Syscall() vs Call()?

Question

I've been experimenting with Go and Win32, and I found these two variants for calling OS functions (code is abbreviated):

modUser32 = syscall.NewLazyDLL("user32.dll")
procMessageBox = modUser32.NewProc("MessageBoxW")

// 1st variant
syscall.Syscall6(procMessageBox.Addr(), 4,
    uintptr(hwnd), toUtf16(msg), toUtf16(caption), uintptr(flags),
    0, 0)

// 2nd variant
procMessageBox.Call(uintptr(hwnd), uintptr(hwnd),
    toUtf16(msg), toUtf16(caption), uintptr(flags))

2nd variant is obviously simpler, but are there any disadvantages to it?

Answer 1

They basically don't make much difference, Syscall may just be a layer of encapsulation for the Call . Both variants have a limit on the number of parameters.

syscall.Syscall
syscall.Syscall6
syscall.Syscall9
syscall.Syscall12
syscall.Syscall15

Corresponding to parameters <= 3/6/9/12/15.

Call() method has up to 15 parameters.