Auto merge of #51319 - Mark-Simulacrum:rollup, r=Mark-Simulacrum

Rollup of 6 pull requests

Successful merges:

 - #51143 (Specify that packed types must derive, not implement, Copy)
 - #51226 (Make Layout's align a NonZeroUsize)
 - #51297 (Fix run button style)
 - #51306 (impl Default for &mut str)
 - #51312 (Clarify the difference between get_mut and into_mut for OccupiedEntry)
 - #51313 (use type name in E0599 enum variant suggestion)

Failed merges:

1 files changed, 15 insertions, 2 deletions

diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index 935ea4b62b5..5cbd8891364 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -2250,6 +2250,11 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> {
 
     /// Gets a mutable reference to the value in the entry.
     ///
+    /// If you need a reference to the `OccupiedEntry` which may outlive the
+    /// destruction of the `Entry` value, see [`into_mut`].
+    ///
+    /// [`into_mut`]: #method.into_mut
+    ///
     /// # Examples
     ///
     /// ```
@@ -2261,10 +2266,14 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> {
     ///
     /// assert_eq!(map["poneyland"], 12);
     /// if let Entry::Occupied(mut o) = map.entry("poneyland") {
-    ///      *o.get_mut() += 10;
+    ///     *o.get_mut() += 10;
+    ///     assert_eq!(*o.get(), 22);
+    ///
+    ///     // We can use the same Entry multiple times.
+    ///     *o.get_mut() += 2;
     /// }
     ///
-    /// assert_eq!(map["poneyland"], 22);
+    /// assert_eq!(map["poneyland"], 24);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut V {
@@ -2274,6 +2283,10 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> {
     /// Converts the OccupiedEntry into a mutable reference to the value in the entry
     /// with a lifetime bound to the map itself.
     ///
+    /// If you need multiple references to the `OccupiedEntry`, see [`get_mut`].
+    ///
+    /// [`get_mut`]: #method.get_mut
+    ///
     /// # Examples
     ///
     /// ```