Rollup merge of rust-lang#76926 - ssomers:btree_cleanup_1, r=Mark-Simulacrum

BTreeMap: code readability tweaks

Gathered over the past months

r? @Mark-Simulacrum

Author: RalfJung

library/alloc/src/collections/btree/map.rs

@@ -1715,7 +1715,7 @@ impl<'a, K: 'a, V: 'a> DrainFilterInner<'a, K, V> {
     /// Allow Debug implementations to predict the next element.
     pub(super) fn peek(&self) -> Option<(&K, &V)> {
         let edge = self.cur_leaf_edge.as_ref()?;
-        edge.reborrow().next_kv().ok().map(|kv| kv.into_kv())
+        edge.reborrow().next_kv().ok().map(Handle::into_kv)
     }
 
     /// Implementation of a typical `DrainFilter::next` method, given the predicate.

library/alloc/src/collections/btree/navigate.rs

@@ -218,7 +218,7 @@ impl<BorrowType, K, V> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::E
         let mut edge = self.forget_node_type();
         loop {
             edge = match edge.right_kv() {
-                Ok(internal_kv) => return Ok(internal_kv),
+                Ok(kv) => return Ok(kv),
                 Err(last_edge) => match last_edge.into_node().ascend() {
                     Ok(parent_edge) => parent_edge.forget_node_type(),
                     Err(root) => return Err(root),
@@ -239,7 +239,7 @@ impl<BorrowType, K, V> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::E
         let mut edge = self.forget_node_type();
         loop {
             edge = match edge.left_kv() {
-                Ok(internal_kv) => return Ok(internal_kv),
+                Ok(kv) => return Ok(kv),
                 Err(last_edge) => match last_edge.into_node().ascend() {
                     Ok(parent_edge) => parent_edge.forget_node_type(),
                     Err(root) => return Err(root),

library/alloc/src/collections/btree/node.rs

@@ -929,14 +929,14 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, mark
     /// The returned pointer points to the inserted value.
     fn insert(mut self, key: K, val: V) -> (InsertResult<'a, K, V, marker::Leaf>, *mut V) {
         if self.node.len() < CAPACITY {
-            let ptr = self.insert_fit(key, val);
+            let val_ptr = self.insert_fit(key, val);
             let kv = unsafe { Handle::new_kv(self.node, self.idx) };
-            (InsertResult::Fit(kv), ptr)
+            (InsertResult::Fit(kv), val_ptr)
         } else {
             let (middle_kv_idx, insertion) = splitpoint(self.idx);
             let middle = unsafe { Handle::new_kv(self.node, middle_kv_idx) };
             let (mut left, k, v, mut right) = middle.split();
-            let ptr = match insertion {
+            let val_ptr = match insertion {
                 InsertionPlace::Left(insert_idx) => unsafe {
                     Handle::new_edge(left.reborrow_mut(), insert_idx).insert_fit(key, val)
                 },
@@ -948,7 +948,7 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, mark
                     .insert_fit(key, val)
                 },
             };
-            (InsertResult::Split(SplitResult { left: left.forget_type(), k, v, right }), ptr)
+            (InsertResult::Split(SplitResult { left: left.forget_type(), k, v, right }), val_ptr)
         }
     }
 }