Remove usage of as usize in places

And replace it with a safer alternative.

remote/src/net_relay/uuid.rs

@@ -196,8 +196,8 @@ impl Serialize for Uuid {
                 for idx in BYTE_POSITIONS[group]..BYTE_POSITIONS[group + 1] {
                     let byte = self.0[idx];
                     let out_idx = group + 2 * idx;
-                    buf[out_idx] = HEX_CHARS[(byte >> 4) as usize];
-                    buf[out_idx + 1] = HEX_CHARS[(byte & 0b1111) as usize];
+                    buf[out_idx] = HEX_CHARS[usize::from(byte >> 4)];
+                    buf[out_idx + 1] = HEX_CHARS[usize::from(byte & 0b1111)];
                 }
                 if group != 4 {
                     buf[HYPHEN_POSITIONS[group]] = b'-';

src/future.rs

@@ -288,8 +288,7 @@ impl<RT> ActorFutureBuilder<RT> {
         RT: Clone,
     {
         let rt = self.rt;
-        let (inbox, sender, receiver) =
-            inbox::Manager::new_channel(self.inbox_size.0.get() as usize);
+        let (inbox, sender, receiver) = inbox::Manager::new_channel(self.inbox_size.get());
         let actor_ref = ActorRef::local(sender);
         let ctx = actor::Context::new(receiver, rt.clone());
         let actor = match new_actor.new(ctx, argument) {
@@ -351,6 +350,7 @@ impl InboxSize {
 
     /// Returns itself as `usize`.
     pub const fn get(self) -> usize {
+        // TODO: replace with `usize::from`, once const stable.
         self.0.get() as usize
     }
 }