since this is the only usecase, return a *libusbDevice for a new

pointer.

usb/fakelibusb_test.go

@@ -306,7 +306,7 @@ func newFakeLibusb() *fakeLibusb {
 		// without using the full USB stack. Since the fake library uses the
 		// libusbDevice only as an identifier, use an arbitrary unique pointer.
 		// The contents of these pointers is never accessed.
-		fl.fakeDevices[(*libusbDevice)(newCPointer())] = &fakeDevice{
+		fl.fakeDevices[newDevicePointer()] = &fakeDevice{
 			desc: d,
 			alt:  0,
 		}

usb/libusb.go

@@ -426,6 +426,6 @@ func libusbSetDebug(c *libusbContext, lvl int) {
 	C.libusb_set_debug((*C.libusb_context)(c), C.int(lvl))
 }
 
-func newCPointer() unsafe.Pointer {
-	return unsafe.Pointer(C.malloc(1))
+func newDevicePointer() *libusbDevice {
+	return (*libusbDevice)(unsafe.Pointer(C.malloc(1)))
 }