X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=src%2Fliballoc%2Fcollections%2Fbtree%2Fmap.rs;h=b1f0ef0085f2d42a91f4145302ff788c7aea8358;hb=892cb143e5984f220e6b26b48d972bd1f4644298;hp=5b4b1c933472d8abeb16e36df78f8e89db18db56;hpb=82a366ad860b6f0eed639dd103995e6cee1585c7;p=rust.git

diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index 5b4b1c93347..b1f0ef0085f 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -227,7 +227,7 @@ impl<K: Clone, V: Clone> BTreeClone for BTreeMap<K, V> {
 impl<K: Clone + Ord, V: Clone> BTreeClone for BTreeMap<K, V> {
     fn clone_from(&mut self, other: &Self) {
         // This truncates `self` to `other.len()` by calling `split_off` on
-        // the first key after `other.len()` elements if it exists
+        // the first key after `other.len()` elements if it exists.
         let split_off_key = if self.len() > other.len() {
             let diff = self.len() - other.len();
             if diff <= other.len() {
@@ -247,11 +247,10 @@ fn clone_from(&mut self, other: &Self) {
         // After truncation, `self` is at most as long as `other` so this loop
         // replaces every key-value pair in `self`. Since `oiter` is in sorted
         // order and the structure of the `BTreeMap` stays the same,
-        // the BTree invariants are maintained at the end of the loop
+        // the BTree invariants are maintained at the end of the loop.
         while !siter.is_empty() {
             if let Some((ok, ov)) = oiter.next() {
-                // SAFETY: This is safe because the `siter.front != siter.back` check
-                // ensures that `siter` is nonempty
+                // SAFETY: This is safe because `siter` is nonempty.
                 let (sk, sv) = unsafe { siter.next_unchecked() };
                 sk.clone_from(ok);
                 sv.clone_from(ov);
@@ -259,7 +258,7 @@ fn clone_from(&mut self, other: &Self) {
                 break;
             }
         }
-        // If `other` is longer than `self`, the remaining elements are inserted
+        // If `other` is longer than `self`, the remaining elements are inserted.
         self.extend(oiter.map(|(k, v)| ((*k).clone(), (*v).clone())));
     }
 }
@@ -1471,7 +1470,22 @@ fn into_iter(self) -> IntoIter<K, V> {
 #[stable(feature = "btree_drop", since = "1.7.0")]
 impl<K, V> Drop for IntoIter<K, V> {
     fn drop(&mut self) {
-        self.for_each(drop);
+        struct DropGuard<'a, K, V>(&'a mut IntoIter<K, V>);
+
+        impl<'a, K, V> Drop for DropGuard<'a, K, V> {
+            fn drop(&mut self) {
+                // Continue the same loop we perform below. This only runs when unwinding, so we
+                // don't have to care about panics this time (they'll abort).
+                while let Some(_) = self.0.next() {}
+            }
+        }
+
+        while let Some(pair) = self.next() {
+            let guard = DropGuard(self);
+            drop(pair);
+            mem::forget(guard);
+        }
+
         unsafe {
             let leaf_node = ptr::read(&self.front).into_node();
             if leaf_node.is_shared_root() {