use dyn for trait objects

When switching to Rust 1.38 trait objects without an explicit `dyn`
are deprecated.

Signed-off-by: Andreea Florescu <[email protected]>

Author: andreeaflorescu

devices/src/virtio/block.rs

@@ -670,7 +670,7 @@ mod tests {
     struct DummyBlock {
         block: Block,
         epoll_raw_fd: i32,
-        _receiver: Receiver<Box<EpollHandler>>,
+        _receiver: Receiver<Box<dyn EpollHandler>>,
     }
 
     impl DummyBlock {

devices/src/virtio/net.rs

@@ -980,7 +980,7 @@ mod tests {
     struct DummyNet {
         net: Net,
         epoll_raw_fd: i32,
-        _receiver: Receiver<Box<EpollHandler>>,
+        _receiver: Receiver<Box<dyn EpollHandler>>,
     }
 
     impl DummyNet {

devices/src/virtio/vsock/mod.rs

@@ -282,7 +282,7 @@ mod tests {
         pub device: Vsock<TestBackend>,
 
         // This needs to live here, so that sending the handler, at device activation, works.
-        _handler_receiver: mpsc::Receiver<Box<EpollHandler>>,
+        _handler_receiver: mpsc::Receiver<Box<dyn EpollHandler>>,
     }
 
     impl TestContext {

net_util/src/tap.rs

@@ -442,7 +442,9 @@ mod tests {
     // For a given interface name, this returns a tuple that contains the MAC address of the
     // interface, an object that can be used to send Ethernet frames, and a receiver of
     // Ethernet frames arriving at the specified interface.
-    fn pnet_get_mac_tx_rx(ifname: String) -> (MacAddr, Box<DataLinkSender>, Box<DataLinkReceiver>) {
+    fn pnet_get_mac_tx_rx(
+        ifname: String,
+    ) -> (MacAddr, Box<dyn DataLinkSender>, Box<dyn DataLinkReceiver>) {
         let interface_name_matches = |iface: &NetworkInterface| iface.name == ifname;
 
         // Find the network interface with the provided name.