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Co-authored-by: NDavid Tolnay <dtolnay@gmail.com>

library/std/src/collections/hash/set.rs

@@ -590,8 +590,9 @@ pub fn symmetric_difference<'a>(
     ///
     /// When an equal element is present in `self` and `other`
     /// then the resulting `Intersection` may yield references to
-    /// one or the other, which will be visible in properties of `T`
-    /// not participating in the `Eq` implementation.
+    /// one or the other. This can be relevant if `T` contains fields which
+    /// are not compared by its `Eq` implementation, and may hold different
+    /// value between the two equal copies of `T` in the two sets.
     ///
     /// # Examples
     ///