Fix the comparison of union set sizes

rust-lang · Jan 18, 2021 · 2c66e28 · 2c66e28
1 parent 496b1bc
commit 2c66e28
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/src/set.rs b/src/set.rs
@@ -736,7 +736,9 @@ where
     /// ```
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn union<'a>(&'a self, other: &'a Self) -> Union<'a, T, S, A> {
-        let (smaller, larger) = if self.len() >= other.len() {
+        // We'll iterate one set in full, and only the remaining difference from the other.
+        // Use the smaller set for the difference in order to reduce hash lookups.
+        let (smaller, larger) = if self.len() <= other.len() {
             (self, other)
         } else {
             (other, self)