Auto merge of #79245 - ssomers:btree_curb_ord_bound, r=dtolnay

BTree: remove Ord bound where it is absent elsewhere

Some btree methods don't really need an Ord bound and don't have one, while some methods that more obviously don't need it, do have one.

An example of the former is `iter`, even though it explicitly exposes the work of the Ord implementation (["sorted by key"](https://doc.rust-lang.org/std/collections/struct.BTreeMap.html#method.iter) - but I'm not suggesting it should have the Ord bound). An example of the latter is `new`, which doesn't involve any keys whatsoever.

4 files changed, 22 insertions, 20 deletions

diff --git a/library/alloc/src/collections/btree/map.rs b/library/alloc/src/collections/btree/map.rs
index 8fb9198a7cb..c26388a1db1 100644
--- a/library/alloc/src/collections/btree/map.rs
+++ b/library/alloc/src/collections/btree/map.rs
@@ -500,11 +500,8 @@ impl<K, V> BTreeMap<K, V> {
     /// assert!(a.is_empty());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn clear(&mut self)
-    where
-        K: Ord,
-    {
-        *self = BTreeMap::new();
+    pub fn clear(&mut self) {
+        *self = BTreeMap { root: None, length: 0 };
     }
 
     /// Returns a reference to the value corresponding to the key.
@@ -1227,10 +1224,7 @@ impl<K, V> BTreeMap<K, V> {
     /// ```
     #[inline]
     #[unstable(feature = "map_into_keys_values", issue = "75294")]
-    pub fn into_keys(self) -> IntoKeys<K, V>
-    where
-        K: Ord,
-    {
+    pub fn into_keys(self) -> IntoKeys<K, V> {
         IntoKeys { inner: self.into_iter() }
     }
 
@@ -1253,10 +1247,7 @@ impl<K, V> BTreeMap<K, V> {
     /// ```
     #[inline]
     #[unstable(feature = "map_into_keys_values", issue = "75294")]
-    pub fn into_values(self) -> IntoValues<K, V>
-    where
-        K: Ord,
-    {
+    pub fn into_values(self) -> IntoValues<K, V> {
         IntoValues { inner: self.into_iter() }
     }
 }
diff --git a/library/alloc/src/collections/btree/map/tests.rs b/library/alloc/src/collections/btree/map/tests.rs
index 78edf11d393..1993c6e047d 100644
--- a/library/alloc/src/collections/btree/map/tests.rs
+++ b/library/alloc/src/collections/btree/map/tests.rs
@@ -1711,12 +1711,19 @@ fn test_ord_absence() {
     fn map<K>(mut map: BTreeMap<K, ()>) {
         map.is_empty();
         map.len();
+        map.clear();
         map.iter();
         map.iter_mut();
         map.keys();
         map.values();
         map.values_mut();
-        map.into_iter();
+        if true {
+            map.into_values();
+        } else if true {
+            map.into_iter();
+        } else {
+            map.into_keys();
+        }
     }
 
     fn map_debug<K: Debug>(mut map: BTreeMap<K, ()>) {
@@ -1726,7 +1733,13 @@ fn test_ord_absence() {
         format!("{:?}", map.keys());
         format!("{:?}", map.values());
         format!("{:?}", map.values_mut());
-        format!("{:?}", map.into_iter());
+        if true {
+            format!("{:?}", map.into_iter());
+        } else if true {
+            format!("{:?}", map.into_keys());
+        } else {
+            format!("{:?}", map.into_values());
+        }
     }
 
     fn map_clone<K: Clone>(mut map: BTreeMap<K, ()>) {
diff --git a/library/alloc/src/collections/btree/set.rs b/library/alloc/src/collections/btree/set.rs
index 8072762d879..c619b5bf8ed 100644
--- a/library/alloc/src/collections/btree/set.rs
+++ b/library/alloc/src/collections/btree/set.rs
@@ -457,10 +457,7 @@ impl<T> BTreeSet<T> {
     /// assert!(v.is_empty());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn clear(&mut self)
-    where
-        T: Ord,
-    {
+    pub fn clear(&mut self) {
         self.map.clear()
     }
 
diff --git a/library/alloc/src/collections/btree/set/tests.rs b/library/alloc/src/collections/btree/set/tests.rs
index 79e469eb0db..3762af7236a 100644
--- a/library/alloc/src/collections/btree/set/tests.rs
+++ b/library/alloc/src/collections/btree/set/tests.rs
@@ -641,9 +641,10 @@ fn test_send() {
 
 #[allow(dead_code)]
 fn test_ord_absence() {
-    fn set<K>(set: BTreeSet<K>) {
+    fn set<K>(mut set: BTreeSet<K>) {
         set.is_empty();
         set.len();
+        set.clear();
         set.iter();
         set.into_iter();
     }