tokio: simplify Option handling with idiomatic combinators (#8336)

tokio-util/src/codec/length_delimited.rs

@@ -1040,7 +1040,7 @@ impl Builder {
 
     fn num_head_bytes(&self) -> usize {
         let num = self.length_field_offset + self.length_field_len;
-        cmp::max(num, self.num_skip.unwrap_or(0))
+        cmp::max(num, self.num_skip.unwrap_or_default())
     }
 
     fn get_num_skip(&self) -> usize {

tokio-util/src/time/delay_queue.rs

@@ -580,12 +580,7 @@ impl<T> DelayQueue<T> {
     /// current task for wakeup if the value is not yet available, and returning
     /// `None` if the queue is exhausted.
     pub fn poll_expired(&mut self, cx: &mut task::Context<'_>) -> Poll<Option<Expired<T>>> {
-        if !self
-            .waker
-            .as_ref()
-            .map(|w| w.will_wake(cx.waker()))
-            .unwrap_or(false)
-        {
+        if !self.waker.as_ref().is_some_and(|w| w.will_wake(cx.waker())) {
             self.waker = Some(cx.waker().clone());
         }
 

tokio-util/src/time/wheel/mod.rs

@@ -111,8 +111,7 @@ where
         debug_assert!({
             self.levels[level]
                 .next_expiration(self.elapsed)
-                .map(|e| e.deadline >= self.elapsed)
-                .unwrap_or(true)
+                .map_or(true, |e| e.deadline >= self.elapsed)
         });
 
         Ok(())