Use rayon-1.9.0's collect_vec_list

Cargo.toml

@@ -20,7 +20,7 @@ arbitrary = { version = "1.0", optional = true, default-features = false }
 quickcheck = { version = "1.0", optional = true, default-features = false }
 serde = { version = "1.0", optional = true, default-features = false }
 borsh = { version = "1.2", optional = true, default-features = false }
-rayon = { version = "1.5.3", optional = true }
+rayon = { version = "1.9", optional = true }
 
 # Internal feature, only used when building as part of rustc,
 # not part of the stable interface of this crate.

src/rayon/mod.rs

@@ -12,18 +12,5 @@ pub mod set;
 // This form of intermediate collection is also how Rayon collects `HashMap`.
 // Note that the order will also be preserved!
 fn collect<I: IntoParallelIterator>(iter: I) -> LinkedList<Vec<I::Item>> {
-    iter.into_par_iter()
-        .fold(Vec::new, |mut vec, elem| {
-            vec.push(elem);
-            vec
-        })
-        .map(|vec| {
-            let mut list = LinkedList::new();
-            list.push_back(vec);
-            list
-        })
-        .reduce(LinkedList::new, |mut list1, mut list2| {
-            list1.append(&mut list2);
-            list1
-        })
+    iter.into_par_iter().collect_vec_list()
 }