Documentation states:

(4) Conversion of a Pointer to a uintptr when calling syscall.Syscall.
The Syscall functions in package syscall pass their uintptr arguments directly to the operating system, which then may, depending on the details of the call, reinterpret some of them as pointers. That is, the system call implementation is implicitly converting certain arguments back from uintptr to pointer.
If a pointer argument must be converted to uintptr for use as an argument, that conversion must appear in the call expression itself

However, there are calls within /x/sys/windows that do not follow this requirement. For an example, this call is casting an unsafe.Pointer to uintptr then is then passed to here

The generated calls in windows/zsyscall_windows.go should likely accept unsafe.Pointer arguments instead of uintptr.

Examples

// from windows/svc/service.go
handle, err := windows.RegisterServiceCtrlHandlerEx(windows.StringToUTF16Ptr(theService.name), ctlHandlerCallback, uintptr(unsafe.Pointer(&theService)))

// from windows/zsyscall_windows.go
func RegisterServiceCtrlHandlerEx(serviceName *uint16, handlerProc uintptr, context uintptr) (handle Handle, err error) {
	r0, _, e1 := syscall.Syscall(procRegisterServiceCtrlHandlerExW.Addr(), 3, uintptr(unsafe.Pointer(serviceName)), uintptr(handlerProc), uintptr(context))
	handle = Handle(r0)
	if handle == 0 {
		err = errnoErr(e1)
	}
	return
}