Document overrides of `clone_from()`

Specifically, when an override doesn't just forward to an inner type,
document the behavior and that it's preferred over simply assigning
a clone of source. Also, change instances where the second parameter is
"other" to "source".

1 files changed, 4 insertions, 0 deletions

diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index 98ded7f6cdf..fd36583ec8e 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -2084,6 +2084,10 @@ impl Clone for String {
         String { vec: self.vec.clone() }
     }
 
+    /// Clones the contents of `source` into `self`.
+    ///
+    /// This method is preferred over simply assigning `source.clone()` to `self`,
+    /// as it avoids reallocation if possible.
     fn clone_from(&mut self, source: &Self) {
         self.vec.clone_from(&source.vec);
     }