Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

16 files changed, 1652 insertions, 0 deletions

diff --git a/third_party/rust/rayon/tests/chars.rs b/third_party/rust/rayon/tests/chars.rs
new file mode 100644
index 0000000000..ac8e3f3046
--- /dev/null
+++ b/third_party/rust/rayon/tests/chars.rs
@@ -0,0 +1,39 @@
+use rayon::prelude::*;
+use std::char;
+
+#[test]
+fn half_open_correctness() {
+    let low = char::from_u32(0xD800 - 0x7).unwrap();
+    let high = char::from_u32(0xE000 + 0x7).unwrap();
+
+    let range = low..high;
+    let mut chars: Vec<char> = range.into_par_iter().collect();
+    chars.sort();
+
+    assert_eq!(
+        chars,
+        vec![
+            '\u{D7F9}', '\u{D7FA}', '\u{D7FB}', '\u{D7FC}', '\u{D7FD}', '\u{D7FE}', '\u{D7FF}',
+            '\u{E000}', '\u{E001}', '\u{E002}', '\u{E003}', '\u{E004}', '\u{E005}', '\u{E006}',
+        ]
+    );
+}
+
+#[test]
+fn closed_correctness() {
+    let low = char::from_u32(0xD800 - 0x7).unwrap();
+    let high = char::from_u32(0xE000 + 0x7).unwrap();
+
+    let range = low..=high;
+    let mut chars: Vec<char> = range.into_par_iter().collect();
+    chars.sort();
+
+    assert_eq!(
+        chars,
+        vec![
+            '\u{D7F9}', '\u{D7FA}', '\u{D7FB}', '\u{D7FC}', '\u{D7FD}', '\u{D7FE}', '\u{D7FF}',
+            '\u{E000}', '\u{E001}', '\u{E002}', '\u{E003}', '\u{E004}', '\u{E005}', '\u{E006}',
+            '\u{E007}',
+        ]
+    );
+}
diff --git a/third_party/rust/rayon/tests/clones.rs b/third_party/rust/rayon/tests/clones.rs
new file mode 100644
index 0000000000..2b78f09876
--- /dev/null
+++ b/third_party/rust/rayon/tests/clones.rs
@@ -0,0 +1,200 @@
+use rayon::prelude::*;
+
+fn check<I>(iter: I)
+where
+    I: ParallelIterator + Clone,
+    I::Item: std::fmt::Debug + PartialEq,
+{
+    let a: Vec<_> = iter.clone().collect();
+    let b: Vec<_> = iter.collect();
+    assert_eq!(a, b);
+}
+
+#[test]
+fn clone_binary_heap() {
+    use std::collections::BinaryHeap;
+    let heap: BinaryHeap<_> = (0..1000).collect();
+    check(heap.par_iter());
+    check(heap.into_par_iter());
+}
+
+#[test]
+fn clone_btree_map() {
+    use std::collections::BTreeMap;
+    let map: BTreeMap<_, _> = (0..1000).enumerate().collect();
+    check(map.par_iter());
+}
+
+#[test]
+fn clone_btree_set() {
+    use std::collections::BTreeSet;
+    let set: BTreeSet<_> = (0..1000).collect();
+    check(set.par_iter());
+}
+
+#[test]
+fn clone_hash_map() {
+    use std::collections::HashMap;
+    let map: HashMap<_, _> = (0..1000).enumerate().collect();
+    check(map.par_iter());
+}
+
+#[test]
+fn clone_hash_set() {
+    use std::collections::HashSet;
+    let set: HashSet<_> = (0..1000).collect();
+    check(set.par_iter());
+}
+
+#[test]
+fn clone_linked_list() {
+    use std::collections::LinkedList;
+    let list: LinkedList<_> = (0..1000).collect();
+    check(list.par_iter());
+    check(list.into_par_iter());
+}
+
+#[test]
+fn clone_vec_deque() {
+    use std::collections::VecDeque;
+    let deque: VecDeque<_> = (0..1000).collect();
+    check(deque.par_iter());
+    check(deque.into_par_iter());
+}
+
+#[test]
+fn clone_option() {
+    let option = Some(0);
+    check(option.par_iter());
+    check(option.into_par_iter());
+}
+
+#[test]
+fn clone_result() {
+    let result = Ok::<_, ()>(0);
+    check(result.par_iter());
+    check(result.into_par_iter());
+}
+
+#[test]
+fn clone_range() {
+    check((0..1000).into_par_iter());
+}
+
+#[test]
+fn clone_range_inclusive() {
+    check((0..=1000).into_par_iter());
+}
+
+#[test]
+fn clone_str() {
+    let s = include_str!("clones.rs");
+    check(s.par_chars());
+    check(s.par_lines());
+    check(s.par_split('\n'));
+    check(s.par_split_terminator('\n'));
+    check(s.par_split_whitespace());
+}
+
+#[test]
+fn clone_vec() {
+    let v: Vec<_> = (0..1000).collect();
+    check(v.par_iter());
+    check(v.par_chunks(42));
+    check(v.par_chunks_exact(42));
+    check(v.par_rchunks(42));
+    check(v.par_rchunks_exact(42));
+    check(v.par_windows(42));
+    check(v.par_split(|x| x % 3 == 0));
+    check(v.into_par_iter());
+}
+
+#[test]
+fn clone_array() {
+    let a = [0i32; 100];
+    check(a.into_par_iter());
+}
+
+#[test]
+fn clone_adaptors() {
+    let v: Vec<_> = (0..1000).map(Some).collect();
+    check(v.par_iter().chain(&v));
+    check(v.par_iter().cloned());
+    check(v.par_iter().copied());
+    check(v.par_iter().enumerate());
+    check(v.par_iter().filter(|_| true));
+    check(v.par_iter().filter_map(|x| *x));
+    check(v.par_iter().flat_map(|x| *x));
+    check(v.par_iter().flat_map_iter(|x| *x));
+    check(v.par_iter().flatten());
+    check(v.par_iter().flatten_iter());
+    check(v.par_iter().with_max_len(1).fold(|| 0, |x, _| x));
+    check(v.par_iter().with_max_len(1).fold_with(0, |x, _| x));
+    check(v.par_iter().with_max_len(1).fold_chunks(1, || 0, |x, _| x));
+    check(
+        v.par_iter()
+            .with_max_len(1)
+            .fold_chunks_with(1, 0, |x, _| x),
+    );
+    check(v.par_iter().with_max_len(1).try_fold(|| 0, |_, &x| x));
+    check(v.par_iter().with_max_len(1).try_fold_with(0, |_, &x| x));
+    check(v.par_iter().inspect(|_| ()));
+    check(v.par_iter().update(|_| ()));
+    check(v.par_iter().interleave(&v));
+    check(v.par_iter().interleave_shortest(&v));
+    check(v.par_iter().intersperse(&None));
+    check(v.par_iter().chunks(3));
+    check(v.par_iter().map(|x| x));
+    check(v.par_iter().map_with(0, |_, x| x));
+    check(v.par_iter().map_init(|| 0, |_, x| x));
+    check(v.par_iter().panic_fuse());
+    check(v.par_iter().positions(|_| true));
+    check(v.par_iter().rev());
+    check(v.par_iter().skip(1));
+    check(v.par_iter().take(1));
+    check(v.par_iter().cloned().while_some());
+    check(v.par_iter().with_max_len(1));
+    check(v.par_iter().with_min_len(1));
+    check(v.par_iter().zip(&v));
+    check(v.par_iter().zip_eq(&v));
+    check(v.par_iter().step_by(2));
+}
+
+#[test]
+fn clone_empty() {
+    check(rayon::iter::empty::<i32>());
+}
+
+#[test]
+fn clone_once() {
+    check(rayon::iter::once(10));
+}
+
+#[test]
+fn clone_repeat() {
+    let x: Option<i32> = None;
+    check(rayon::iter::repeat(x).while_some());
+    check(rayon::iter::repeatn(x, 1000));
+}
+
+#[test]
+fn clone_splitter() {
+    check(rayon::iter::split(0..1000, |x| (x, None)));
+}
+
+#[test]
+fn clone_multizip() {
+    let v: &Vec<_> = &(0..1000).collect();
+    check((v,).into_par_iter());
+    check((v, v).into_par_iter());
+    check((v, v, v).into_par_iter());
+    check((v, v, v, v).into_par_iter());
+    check((v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v, v, v, v, v).into_par_iter());
+}
diff --git a/third_party/rust/rayon/tests/collect.rs b/third_party/rust/rayon/tests/collect.rs
new file mode 100644
index 0000000000..48b80f6998
--- /dev/null
+++ b/third_party/rust/rayon/tests/collect.rs
@@ -0,0 +1,111 @@
+use rayon::prelude::*;
+
+use std::panic;
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::Ordering;
+use std::sync::Mutex;
+
+#[test]
+fn collect_drop_on_unwind() {
+    struct Recorddrop<'a>(i64, &'a Mutex<Vec<i64>>);
+
+    impl<'a> Drop for Recorddrop<'a> {
+        fn drop(&mut self) {
+            self.1.lock().unwrap().push(self.0);
+        }
+    }
+
+    let test_collect_panic = |will_panic: bool| {
+        let test_vec_len = 1024;
+        let panic_point = 740;
+
+        let mut inserts = Mutex::new(Vec::new());
+        let mut drops = Mutex::new(Vec::new());
+
+        let mut a = (0..test_vec_len).collect::<Vec<_>>();
+        let b = (0..test_vec_len).collect::<Vec<_>>();
+
+        let _result = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+            let mut result = Vec::new();
+            a.par_iter_mut()
+                .zip(&b)
+                .map(|(&mut a, &b)| {
+                    if a > panic_point && will_panic {
+                        panic!("unwinding for test");
+                    }
+                    let elt = a + b;
+                    inserts.lock().unwrap().push(elt);
+                    Recorddrop(elt, &drops)
+                })
+                .collect_into_vec(&mut result);
+
+            // If we reach this point, this must pass
+            assert_eq!(a.len(), result.len());
+        }));
+
+        let inserts = inserts.get_mut().unwrap();
+        let drops = drops.get_mut().unwrap();
+        println!("{:?}", inserts);
+        println!("{:?}", drops);
+
+        assert_eq!(inserts.len(), drops.len(), "Incorrect number of drops");
+        // sort to normalize order
+        inserts.sort();
+        drops.sort();
+        assert_eq!(inserts, drops, "Incorrect elements were dropped");
+    };
+
+    for &should_panic in &[true, false] {
+        test_collect_panic(should_panic);
+    }
+}
+
+#[test]
+fn collect_drop_on_unwind_zst() {
+    static INSERTS: AtomicUsize = AtomicUsize::new(0);
+    static DROPS: AtomicUsize = AtomicUsize::new(0);
+
+    struct RecorddropZst;
+
+    impl Drop for RecorddropZst {
+        fn drop(&mut self) {
+            DROPS.fetch_add(1, Ordering::SeqCst);
+        }
+    }
+
+    let test_collect_panic = |will_panic: bool| {
+        INSERTS.store(0, Ordering::SeqCst);
+        DROPS.store(0, Ordering::SeqCst);
+
+        let test_vec_len = 1024;
+        let panic_point = 740;
+
+        let a = (0..test_vec_len).collect::<Vec<_>>();
+
+        let _result = panic::catch_unwind(panic::AssertUnwindSafe(|| {
+            let mut result = Vec::new();
+            a.par_iter()
+                .map(|&a| {
+                    if a > panic_point && will_panic {
+                        panic!("unwinding for test");
+                    }
+                    INSERTS.fetch_add(1, Ordering::SeqCst);
+                    RecorddropZst
+                })
+                .collect_into_vec(&mut result);
+
+            // If we reach this point, this must pass
+            assert_eq!(a.len(), result.len());
+        }));
+
+        let inserts = INSERTS.load(Ordering::SeqCst);
+        let drops = DROPS.load(Ordering::SeqCst);
+
+        assert_eq!(inserts, drops, "Incorrect number of drops");
+        assert!(will_panic || drops == test_vec_len)
+    };
+
+    for &should_panic in &[true, false] {
+        test_collect_panic(should_panic);
+    }
+}
diff --git a/third_party/rust/rayon/tests/cross-pool.rs b/third_party/rust/rayon/tests/cross-pool.rs
new file mode 100644
index 0000000000..f0a2128a77
--- /dev/null
+++ b/third_party/rust/rayon/tests/cross-pool.rs
@@ -0,0 +1,21 @@
+use rayon::prelude::*;
+use rayon::ThreadPoolBuilder;
+
+#[test]
+fn cross_pool_busy() {
+    let pool1 = ThreadPoolBuilder::new().num_threads(1).build().unwrap();
+    let pool2 = ThreadPoolBuilder::new().num_threads(1).build().unwrap();
+
+    let n: i32 = 100;
+    let sum: i32 = pool1.install(move || {
+        // Each item will block on pool2, but pool1 can continue processing other work from the
+        // parallel iterator in the meantime. There's a chance that pool1 will still be awake to
+        // see the latch set without being tickled, and then it will drop that stack job. The latch
+        // internals must not assume that the job will still be alive after it's set!
+        (1..=n)
+            .into_par_iter()
+            .map(|i| pool2.install(move || i))
+            .sum()
+    });
+    assert_eq!(sum, n * (n + 1) / 2);
+}
diff --git a/third_party/rust/rayon/tests/debug.rs b/third_party/rust/rayon/tests/debug.rs
new file mode 100644
index 0000000000..1cbf4e6edc
--- /dev/null
+++ b/third_party/rust/rayon/tests/debug.rs
@@ -0,0 +1,221 @@
+use rayon::prelude::*;
+use std::fmt::Debug;
+
+fn check<I>(iter: I)
+where
+    I: ParallelIterator + Debug,
+{
+    println!("{:?}", iter);
+}
+
+#[test]
+fn debug_binary_heap() {
+    use std::collections::BinaryHeap;
+    let mut heap: BinaryHeap<_> = (0..10).collect();
+    check(heap.par_iter());
+    check(heap.par_drain());
+    check(heap.into_par_iter());
+}
+
+#[test]
+fn debug_btree_map() {
+    use std::collections::BTreeMap;
+    let mut map: BTreeMap<_, _> = (0..10).enumerate().collect();
+    check(map.par_iter());
+    check(map.par_iter_mut());
+    check(map.into_par_iter());
+}
+
+#[test]
+fn debug_btree_set() {
+    use std::collections::BTreeSet;
+    let set: BTreeSet<_> = (0..10).collect();
+    check(set.par_iter());
+    check(set.into_par_iter());
+}
+
+#[test]
+fn debug_hash_map() {
+    use std::collections::HashMap;
+    let mut map: HashMap<_, _> = (0..10).enumerate().collect();
+    check(map.par_iter());
+    check(map.par_iter_mut());
+    check(map.par_drain());
+    check(map.into_par_iter());
+}
+
+#[test]
+fn debug_hash_set() {
+    use std::collections::HashSet;
+    let mut set: HashSet<_> = (0..10).collect();
+    check(set.par_iter());
+    check(set.par_drain());
+    check(set.into_par_iter());
+}
+
+#[test]
+fn debug_linked_list() {
+    use std::collections::LinkedList;
+    let mut list: LinkedList<_> = (0..10).collect();
+    check(list.par_iter());
+    check(list.par_iter_mut());
+    check(list.into_par_iter());
+}
+
+#[test]
+fn debug_vec_deque() {
+    use std::collections::VecDeque;
+    let mut deque: VecDeque<_> = (0..10).collect();
+    check(deque.par_iter());
+    check(deque.par_iter_mut());
+    check(deque.par_drain(..));
+    check(deque.into_par_iter());
+}
+
+#[test]
+fn debug_option() {
+    let mut option = Some(0);
+    check(option.par_iter());
+    check(option.par_iter_mut());
+    check(option.into_par_iter());
+}
+
+#[test]
+fn debug_result() {
+    let mut result = Ok::<_, ()>(0);
+    check(result.par_iter());
+    check(result.par_iter_mut());
+    check(result.into_par_iter());
+}
+
+#[test]
+fn debug_range() {
+    check((0..10).into_par_iter());
+}
+
+#[test]
+fn debug_range_inclusive() {
+    check((0..=10).into_par_iter());
+}
+
+#[test]
+fn debug_str() {
+    let s = "a b c d\ne f g";
+    check(s.par_chars());
+    check(s.par_lines());
+    check(s.par_split('\n'));
+    check(s.par_split_terminator('\n'));
+    check(s.par_split_whitespace());
+}
+
+#[test]
+fn debug_string() {
+    let mut s = "a b c d\ne f g".to_string();
+    s.par_drain(..);
+}
+
+#[test]
+fn debug_vec() {
+    let mut v: Vec<_> = (0..10).collect();
+    check(v.par_iter());
+    check(v.par_iter_mut());
+    check(v.par_chunks(42));
+    check(v.par_chunks_exact(42));
+    check(v.par_chunks_mut(42));
+    check(v.par_chunks_exact_mut(42));
+    check(v.par_rchunks(42));
+    check(v.par_rchunks_exact(42));
+    check(v.par_rchunks_mut(42));
+    check(v.par_rchunks_exact_mut(42));
+    check(v.par_windows(42));
+    check(v.par_split(|x| x % 3 == 0));
+    check(v.par_split_mut(|x| x % 3 == 0));
+    check(v.par_drain(..));
+    check(v.into_par_iter());
+}
+
+#[test]
+fn debug_array() {
+    let a = [0i32; 10];
+    check(a.into_par_iter());
+}
+
+#[test]
+fn debug_adaptors() {
+    let v: Vec<_> = (0..10).collect();
+    check(v.par_iter().chain(&v));
+    check(v.par_iter().cloned());
+    check(v.par_iter().copied());
+    check(v.par_iter().enumerate());
+    check(v.par_iter().filter(|_| true));
+    check(v.par_iter().filter_map(Some));
+    check(v.par_iter().flat_map(Some));
+    check(v.par_iter().flat_map_iter(Some));
+    check(v.par_iter().map(Some).flatten());
+    check(v.par_iter().map(Some).flatten_iter());
+    check(v.par_iter().fold(|| 0, |x, _| x));
+    check(v.par_iter().fold_with(0, |x, _| x));
+    check(v.par_iter().fold_chunks(3, || 0, |x, _| x));
+    check(v.par_iter().fold_chunks_with(3, 0, |x, _| x));
+    check(v.par_iter().try_fold(|| 0, |x, _| Some(x)));
+    check(v.par_iter().try_fold_with(0, |x, _| Some(x)));
+    check(v.par_iter().inspect(|_| ()));
+    check(v.par_iter().update(|_| ()));
+    check(v.par_iter().interleave(&v));
+    check(v.par_iter().interleave_shortest(&v));
+    check(v.par_iter().intersperse(&-1));
+    check(v.par_iter().chunks(3));
+    check(v.par_iter().map(|x| x));
+    check(v.par_iter().map_with(0, |_, x| x));
+    check(v.par_iter().map_init(|| 0, |_, x| x));
+    check(v.par_iter().panic_fuse());
+    check(v.par_iter().positions(|_| true));
+    check(v.par_iter().rev());
+    check(v.par_iter().skip(1));
+    check(v.par_iter().take(1));
+    check(v.par_iter().map(Some).while_some());
+    check(v.par_iter().with_max_len(1));
+    check(v.par_iter().with_min_len(1));
+    check(v.par_iter().zip(&v));
+    check(v.par_iter().zip_eq(&v));
+    check(v.par_iter().step_by(2));
+}
+
+#[test]
+fn debug_empty() {
+    check(rayon::iter::empty::<i32>());
+}
+
+#[test]
+fn debug_once() {
+    check(rayon::iter::once(10));
+}
+
+#[test]
+fn debug_repeat() {
+    let x: Option<i32> = None;
+    check(rayon::iter::repeat(x));
+    check(rayon::iter::repeatn(x, 10));
+}
+
+#[test]
+fn debug_splitter() {
+    check(rayon::iter::split(0..10, |x| (x, None)));
+}
+
+#[test]
+fn debug_multizip() {
+    let v: &Vec<_> = &(0..10).collect();
+    check((v,).into_par_iter());
+    check((v, v).into_par_iter());
+    check((v, v, v).into_par_iter());
+    check((v, v, v, v).into_par_iter());
+    check((v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v, v, v, v).into_par_iter());
+    check((v, v, v, v, v, v, v, v, v, v, v, v).into_par_iter());
+}
diff --git a/third_party/rust/rayon/tests/drain_vec.rs b/third_party/rust/rayon/tests/drain_vec.rs
new file mode 100644
index 0000000000..08f1120b79
--- /dev/null
+++ b/third_party/rust/rayon/tests/drain_vec.rs
@@ -0,0 +1,41 @@
+use rayon::prelude::*;
+
+#[test]
+fn drain_vec_yielded() {
+    let mut vec_org = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+    let yielded = vec_org.par_drain(0..5).collect::<Vec<_>>();
+
+    assert_eq!(&yielded, &[0, 1, 2, 3, 4]);
+    assert_eq!(&vec_org, &[5, 6, 7, 8, 9]);
+}
+
+#[test]
+fn drain_vec_dropped() {
+    let mut vec_org = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+    let yielded = vec_org.par_drain(0..5);
+
+    drop(yielded);
+    assert_eq!(&vec_org, &[5, 6, 7, 8, 9]);
+}
+
+#[test]
+fn drain_vec_empty_range_yielded() {
+    let mut vec_org = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+    let yielded = vec_org.par_drain(5..5).collect::<Vec<_>>();
+
+    assert_eq!(&yielded, &[]);
+    assert_eq!(&vec_org, &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
+}
+
+#[test]
+fn drain_vec_empty_range_dropped() {
+    let mut vec_org = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+
+    let yielded = vec_org.par_drain(5..5);
+
+    drop(yielded);
+    assert_eq!(&vec_org, &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
+}
diff --git a/third_party/rust/rayon/tests/intersperse.rs b/third_party/rust/rayon/tests/intersperse.rs
new file mode 100644
index 0000000000..aaa5b6530d
--- /dev/null
+++ b/third_party/rust/rayon/tests/intersperse.rs
@@ -0,0 +1,60 @@
+use rayon::prelude::*;
+
+#[test]
+fn check_intersperse() {
+    let v: Vec<_> = (0..1000).into_par_iter().intersperse(-1).collect();
+    assert_eq!(v.len(), 1999);
+    for (i, x) in v.into_iter().enumerate() {
+        assert_eq!(x, if i % 2 == 0 { i as i32 / 2 } else { -1 });
+    }
+}
+
+#[test]
+fn check_intersperse_again() {
+    let v: Vec<_> = (0..1000)
+        .into_par_iter()
+        .intersperse(-1)
+        .intersperse(-2)
+        .collect();
+    assert_eq!(v.len(), 3997);
+    for (i, x) in v.into_iter().enumerate() {
+        let y = match i % 4 {
+            0 => i as i32 / 4,
+            2 => -1,
+            _ => -2,
+        };
+        assert_eq!(x, y);
+    }
+}
+
+#[test]
+fn check_intersperse_unindexed() {
+    let v: Vec<_> = (0..1000).map(|i| i.to_string()).collect();
+    let s = v.join(",");
+    let s2 = v.join(";");
+    let par: String = s.par_split(',').intersperse(";").collect();
+    assert_eq!(par, s2);
+}
+
+#[test]
+fn check_intersperse_producer() {
+    (0..1000)
+        .into_par_iter()
+        .intersperse(-1)
+        .zip_eq(0..1999)
+        .for_each(|(x, i)| {
+            assert_eq!(x, if i % 2 == 0 { i / 2 } else { -1 });
+        });
+}
+
+#[test]
+fn check_intersperse_rev() {
+    (0..1000)
+        .into_par_iter()
+        .intersperse(-1)
+        .zip_eq(0..1999)
+        .rev()
+        .for_each(|(x, i)| {
+            assert_eq!(x, if i % 2 == 0 { i / 2 } else { -1 });
+        });
+}
diff --git a/third_party/rust/rayon/tests/issue671-unzip.rs b/third_party/rust/rayon/tests/issue671-unzip.rs
new file mode 100644
index 0000000000..c9af7e6e3a
--- /dev/null
+++ b/third_party/rust/rayon/tests/issue671-unzip.rs
@@ -0,0 +1,17 @@
+#![type_length_limit = "10000"]
+
+use rayon::prelude::*;
+
+#[test]
+fn type_length_limit() {
+    let input = vec![1, 2, 3, 4, 5];
+    let (indexes, (squares, cubes)): (Vec<_>, (Vec<_>, Vec<_>)) = input
+        .par_iter()
+        .map(|x| (x * x, x * x * x))
+        .enumerate()
+        .unzip();
+
+    drop(indexes);
+    drop(squares);
+    drop(cubes);
+}
diff --git a/third_party/rust/rayon/tests/issue671.rs b/third_party/rust/rayon/tests/issue671.rs
new file mode 100644
index 0000000000..9d0953fe6a
--- /dev/null
+++ b/third_party/rust/rayon/tests/issue671.rs
@@ -0,0 +1,16 @@
+#![type_length_limit = "500000"]
+
+use rayon::prelude::*;
+
+#[test]
+fn type_length_limit() {
+    let _ = Vec::<Result<(), ()>>::new()
+        .into_par_iter()
+        .map(|x| x)
+        .map(|x| x)
+        .map(|x| x)
+        .map(|x| x)
+        .map(|x| x)
+        .map(|x| x)
+        .collect::<Result<(), ()>>();
+}
diff --git a/third_party/rust/rayon/tests/iter_panic.rs b/third_party/rust/rayon/tests/iter_panic.rs
new file mode 100644
index 0000000000..37d4d6a3af
--- /dev/null
+++ b/third_party/rust/rayon/tests/iter_panic.rs
@@ -0,0 +1,52 @@
+use rayon::prelude::*;
+use rayon::ThreadPoolBuilder;
+use std::ops::Range;
+use std::panic::{self, UnwindSafe};
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+const ITER: Range<i32> = 0..0x1_0000;
+const PANIC: i32 = 0xC000;
+
+fn check(&i: &i32) {
+    if i == PANIC {
+        panic!("boom")
+    }
+}
+
+#[test]
+#[should_panic(expected = "boom")]
+fn iter_panic() {
+    ITER.into_par_iter().for_each(|i| check(&i));
+}
+
+#[test]
+fn iter_panic_fuse() {
+    // We only use a single thread in order to make the behavior
+    // of 'panic_fuse' deterministic
+    let pool = ThreadPoolBuilder::new().num_threads(1).build().unwrap();
+
+    pool.install(|| {
+        fn count(iter: impl ParallelIterator + UnwindSafe) -> usize {
+            let count = AtomicUsize::new(0);
+            let result = panic::catch_unwind(|| {
+                iter.for_each(|_| {
+                    count.fetch_add(1, Ordering::Relaxed);
+                });
+            });
+            assert!(result.is_err());
+            count.into_inner()
+        }
+
+        // Without `panic_fuse()`, we'll reach every item except the panicking one.
+        let expected = ITER.len() - 1;
+        let iter = ITER.into_par_iter().with_max_len(1);
+        assert_eq!(count(iter.clone().inspect(check)), expected);
+
+        // With `panic_fuse()` anywhere in the chain, we'll reach fewer items.
+        assert!(count(iter.clone().inspect(check).panic_fuse()) < expected);
+        assert!(count(iter.clone().panic_fuse().inspect(check)) < expected);
+
+        // Try in reverse to be sure we hit the producer case.
+        assert!(count(iter.panic_fuse().inspect(check).rev()) < expected);
+    });
+}
diff --git a/third_party/rust/rayon/tests/named-threads.rs b/third_party/rust/rayon/tests/named-threads.rs
new file mode 100644
index 0000000000..fd1b0be2d8
--- /dev/null
+++ b/third_party/rust/rayon/tests/named-threads.rs
@@ -0,0 +1,24 @@
+use std::collections::HashSet;
+
+use rayon::prelude::*;
+use rayon::*;
+
+#[test]
+fn named_threads() {
+    ThreadPoolBuilder::new()
+        .thread_name(|i| format!("hello-name-test-{}", i))
+        .build_global()
+        .unwrap();
+
+    const N: usize = 10000;
+
+    let thread_names = (0..N)
+        .into_par_iter()
+        .flat_map(|_| ::std::thread::current().name().map(str::to_owned))
+        .collect::<HashSet<String>>();
+
+    let all_contains_name = thread_names
+        .iter()
+        .all(|name| name.starts_with("hello-name-test-"));
+    assert!(all_contains_name);
+}
diff --git a/third_party/rust/rayon/tests/octillion.rs b/third_party/rust/rayon/tests/octillion.rs
new file mode 100644
index 0000000000..cff2b11920
--- /dev/null
+++ b/third_party/rust/rayon/tests/octillion.rs
@@ -0,0 +1,130 @@
+use rayon::prelude::*;
+
+const OCTILLION: u128 = 1_000_000_000_000_000_000_000_000_000;
+
+/// Produce a parallel iterator for 0u128..10²⁷
+fn octillion() -> rayon::range::Iter<u128> {
+    (0..OCTILLION).into_par_iter()
+}
+
+/// Produce a parallel iterator for 0u128..=10²⁷
+fn octillion_inclusive() -> rayon::range_inclusive::Iter<u128> {
+    (0..=OCTILLION).into_par_iter()
+}
+
+/// Produce a parallel iterator for 0u128..10²⁷ using `flat_map`
+fn octillion_flat() -> impl ParallelIterator<Item = u128> {
+    (0u32..1_000_000_000)
+        .into_par_iter()
+        .with_max_len(1_000)
+        .map(|i| u64::from(i) * 1_000_000_000)
+        .flat_map(|i| {
+            (0u32..1_000_000_000)
+                .into_par_iter()
+                .with_max_len(1_000)
+                .map(move |j| i + u64::from(j))
+        })
+        .map(|i| u128::from(i) * 1_000_000_000)
+        .flat_map(|i| {
+            (0u32..1_000_000_000)
+                .into_par_iter()
+                .with_max_len(1_000)
+                .map(move |j| i + u128::from(j))
+        })
+}
+
+// NOTE: `find_first` and `find_last` currently take too long on 32-bit targets,
+// because the `AtomicUsize` match position has much too limited resolution.
+
+#[test]
+#[cfg_attr(not(target_pointer_width = "64"), ignore)]
+fn find_first_octillion() {
+    let x = octillion().find_first(|_| true);
+    assert_eq!(x, Some(0));
+}
+
+#[test]
+#[cfg_attr(not(target_pointer_width = "64"), ignore)]
+fn find_first_octillion_inclusive() {
+    let x = octillion_inclusive().find_first(|_| true);
+    assert_eq!(x, Some(0));
+}
+
+#[test]
+#[cfg_attr(not(target_pointer_width = "64"), ignore)]
+fn find_first_octillion_flat() {
+    let x = octillion_flat().find_first(|_| true);
+    assert_eq!(x, Some(0));
+}
+
+fn two_threads<F: Send + FnOnce() -> R, R: Send>(f: F) -> R {
+    // FIXME: If we don't use at least two threads, then we end up walking
+    // through the entire iterator sequentially, without the benefit of any
+    // short-circuiting.  We probably don't want testing to wait that long. ;)
+    let builder = rayon::ThreadPoolBuilder::new().num_threads(2);
+    let pool = builder.build().unwrap();
+
+    pool.install(f)
+}
+
+#[test]
+#[cfg_attr(not(target_pointer_width = "64"), ignore)]
+fn find_last_octillion() {
+    // It would be nice if `find_last` could prioritize the later splits,
+    // basically flipping the `join` args, without needing indexed `rev`.
+    // (or could we have an unindexed `rev`?)
+    let x = two_threads(|| octillion().find_last(|_| true));
+    assert_eq!(x, Some(OCTILLION - 1));
+}
+
+#[test]
+#[cfg_attr(not(target_pointer_width = "64"), ignore)]
+fn find_last_octillion_inclusive() {
+    let x = two_threads(|| octillion_inclusive().find_last(|_| true));
+    assert_eq!(x, Some(OCTILLION));
+}
+
+#[test]
+#[cfg_attr(not(target_pointer_width = "64"), ignore)]
+fn find_last_octillion_flat() {
+    let x = two_threads(|| octillion_flat().find_last(|_| true));
+    assert_eq!(x, Some(OCTILLION - 1));
+}
+
+#[test]
+fn find_any_octillion() {
+    let x = two_threads(|| octillion().find_any(|x| *x > OCTILLION / 2));
+    assert!(x.is_some());
+}
+
+#[test]
+fn find_any_octillion_flat() {
+    let x = two_threads(|| octillion_flat().find_any(|x| *x > OCTILLION / 2));
+    assert!(x.is_some());
+}
+
+#[test]
+fn filter_find_any_octillion() {
+    let x = two_threads(|| {
+        octillion()
+            .filter(|x| *x > OCTILLION / 2)
+            .find_any(|_| true)
+    });
+    assert!(x.is_some());
+}
+
+#[test]
+fn filter_find_any_octillion_flat() {
+    let x = two_threads(|| {
+        octillion_flat()
+            .filter(|x| *x > OCTILLION / 2)
+            .find_any(|_| true)
+    });
+    assert!(x.is_some());
+}
+
+#[test]
+fn fold_find_any_octillion_flat() {
+    let x = two_threads(|| octillion_flat().fold(|| (), |_, _| ()).find_any(|_| true));
+    assert!(x.is_some());
+}
diff --git a/third_party/rust/rayon/tests/par_bridge_recursion.rs b/third_party/rust/rayon/tests/par_bridge_recursion.rs
new file mode 100644
index 0000000000..4def0a9e42
--- /dev/null
+++ b/third_party/rust/rayon/tests/par_bridge_recursion.rs
@@ -0,0 +1,30 @@
+use rayon::prelude::*;
+use std::iter::once_with;
+
+const N: usize = 100_000;
+
+#[test]
+fn par_bridge_recursion() {
+    let pool = rayon::ThreadPoolBuilder::new()
+        .num_threads(10)
+        .build()
+        .unwrap();
+
+    let seq: Vec<_> = (0..N).map(|i| (i, i.to_string())).collect();
+
+    pool.broadcast(|_| {
+        let mut par: Vec<_> = (0..N)
+            .into_par_iter()
+            .flat_map(|i| {
+                once_with(move || {
+                    // Using rayon within the serial iterator creates an opportunity for
+                    // work-stealing to make par_bridge's mutex accidentally recursive.
+                    rayon::join(move || i, move || i.to_string())
+                })
+                .par_bridge()
+            })
+            .collect();
+        par.par_sort_unstable();
+        assert_eq!(seq, par);
+    });
+}
diff --git a/third_party/rust/rayon/tests/producer_split_at.rs b/third_party/rust/rayon/tests/producer_split_at.rs
new file mode 100644
index 0000000000..d710504927
--- /dev/null
+++ b/third_party/rust/rayon/tests/producer_split_at.rs
@@ -0,0 +1,394 @@
+use rayon::iter::plumbing::*;
+use rayon::prelude::*;
+
+/// Stress-test indexes for `Producer::split_at`.
+fn check<F, I>(expected: &[I::Item], mut f: F)
+where
+    F: FnMut() -> I,
+    I: IntoParallelIterator,
+    I::Iter: IndexedParallelIterator,
+    I::Item: PartialEq + std::fmt::Debug,
+{
+    map_triples(expected.len() + 1, |i, j, k| {
+        Split::forward(f(), i, j, k, expected);
+        Split::reverse(f(), i, j, k, expected);
+    });
+}
+
+fn map_triples<F>(end: usize, mut f: F)
+where
+    F: FnMut(usize, usize, usize),
+{
+    for i in 0..end {
+        for j in i..end {
+            for k in j..end {
+                f(i, j, k);
+            }
+        }
+    }
+}
+
+#[derive(Debug)]
+struct Split {
+    i: usize,
+    j: usize,
+    k: usize,
+    reverse: bool,
+}
+
+impl Split {
+    fn forward<I>(iter: I, i: usize, j: usize, k: usize, expected: &[I::Item])
+    where
+        I: IntoParallelIterator,
+        I::Iter: IndexedParallelIterator,
+        I::Item: PartialEq + std::fmt::Debug,
+    {
+        let result = iter.into_par_iter().with_producer(Split {
+            i,
+            j,
+            k,
+            reverse: false,
+        });
+        assert_eq!(result, expected);
+    }
+
+    fn reverse<I>(iter: I, i: usize, j: usize, k: usize, expected: &[I::Item])
+    where
+        I: IntoParallelIterator,
+        I::Iter: IndexedParallelIterator,
+        I::Item: PartialEq + std::fmt::Debug,
+    {
+        let result = iter.into_par_iter().with_producer(Split {
+            i,
+            j,
+            k,
+            reverse: true,
+        });
+        assert!(result.iter().eq(expected.iter().rev()));
+    }
+}
+
+impl<T> ProducerCallback<T> for Split {
+    type Output = Vec<T>;
+
+    fn callback<P>(self, producer: P) -> Self::Output
+    where
+        P: Producer<Item = T>,
+    {
+        println!("{:?}", self);
+
+        // Splitting the outer indexes first gets us an arbitrary mid section,
+        // which we then split further to get full test coverage.
+        let (left, d) = producer.split_at(self.k);
+        let (a, mid) = left.split_at(self.i);
+        let (b, c) = mid.split_at(self.j - self.i);
+
+        let a = a.into_iter();
+        let b = b.into_iter();
+        let c = c.into_iter();
+        let d = d.into_iter();
+
+        check_len(&a, self.i);
+        check_len(&b, self.j - self.i);
+        check_len(&c, self.k - self.j);
+
+        let chain = a.chain(b).chain(c).chain(d);
+        if self.reverse {
+            chain.rev().collect()
+        } else {
+            chain.collect()
+        }
+    }
+}
+
+fn check_len<I: ExactSizeIterator>(iter: &I, len: usize) {
+    assert_eq!(iter.size_hint(), (len, Some(len)));
+    assert_eq!(iter.len(), len);
+}
+
+// **** Base Producers ****
+
+#[test]
+fn array() {
+    let a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+    check(&a, || a);
+}
+
+#[test]
+fn empty() {
+    let v = vec![42];
+    check(&v[..0], rayon::iter::empty);
+}
+
+#[test]
+fn once() {
+    let v = vec![42];
+    check(&v, || rayon::iter::once(42));
+}
+
+#[test]
+fn option() {
+    let v = vec![42];
+    check(&v, || Some(42));
+}
+
+#[test]
+fn range() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || 0..10);
+}
+
+#[test]
+fn range_inclusive() {
+    let v: Vec<_> = (0u16..=10).collect();
+    check(&v, || 0u16..=10);
+}
+
+#[test]
+fn repeatn() {
+    let v: Vec<_> = std::iter::repeat(1).take(5).collect();
+    check(&v, || rayon::iter::repeatn(1, 5));
+}
+
+#[test]
+fn slice_iter() {
+    let s: Vec<_> = (0..10).collect();
+    let v: Vec<_> = s.iter().collect();
+    check(&v, || &s);
+}
+
+#[test]
+fn slice_iter_mut() {
+    let mut s: Vec<_> = (0..10).collect();
+    let mut v: Vec<_> = s.clone();
+    let expected: Vec<_> = v.iter_mut().collect();
+
+    map_triples(expected.len() + 1, |i, j, k| {
+        Split::forward(s.par_iter_mut(), i, j, k, &expected);
+        Split::reverse(s.par_iter_mut(), i, j, k, &expected);
+    });
+}
+
+#[test]
+fn slice_chunks() {
+    let s: Vec<_> = (0..10).collect();
+    for len in 1..s.len() + 2 {
+        let v: Vec<_> = s.chunks(len).collect();
+        check(&v, || s.par_chunks(len));
+    }
+}
+
+#[test]
+fn slice_chunks_exact() {
+    let s: Vec<_> = (0..10).collect();
+    for len in 1..s.len() + 2 {
+        let v: Vec<_> = s.chunks_exact(len).collect();
+        check(&v, || s.par_chunks_exact(len));
+    }
+}
+
+#[test]
+fn slice_chunks_mut() {
+    let mut s: Vec<_> = (0..10).collect();
+    let mut v: Vec<_> = s.clone();
+    for len in 1..s.len() + 2 {
+        let expected: Vec<_> = v.chunks_mut(len).collect();
+        map_triples(expected.len() + 1, |i, j, k| {
+            Split::forward(s.par_chunks_mut(len), i, j, k, &expected);
+            Split::reverse(s.par_chunks_mut(len), i, j, k, &expected);
+        });
+    }
+}
+
+#[test]
+fn slice_chunks_exact_mut() {
+    let mut s: Vec<_> = (0..10).collect();
+    let mut v: Vec<_> = s.clone();
+    for len in 1..s.len() + 2 {
+        let expected: Vec<_> = v.chunks_exact_mut(len).collect();
+        map_triples(expected.len() + 1, |i, j, k| {
+            Split::forward(s.par_chunks_exact_mut(len), i, j, k, &expected);
+            Split::reverse(s.par_chunks_exact_mut(len), i, j, k, &expected);
+        });
+    }
+}
+
+#[test]
+fn slice_rchunks() {
+    let s: Vec<_> = (0..10).collect();
+    for len in 1..s.len() + 2 {
+        let v: Vec<_> = s.rchunks(len).collect();
+        check(&v, || s.par_rchunks(len));
+    }
+}
+
+#[test]
+fn slice_rchunks_exact() {
+    let s: Vec<_> = (0..10).collect();
+    for len in 1..s.len() + 2 {
+        let v: Vec<_> = s.rchunks_exact(len).collect();
+        check(&v, || s.par_rchunks_exact(len));
+    }
+}
+
+#[test]
+fn slice_rchunks_mut() {
+    let mut s: Vec<_> = (0..10).collect();
+    let mut v: Vec<_> = s.clone();
+    for len in 1..s.len() + 2 {
+        let expected: Vec<_> = v.rchunks_mut(len).collect();
+        map_triples(expected.len() + 1, |i, j, k| {
+            Split::forward(s.par_rchunks_mut(len), i, j, k, &expected);
+            Split::reverse(s.par_rchunks_mut(len), i, j, k, &expected);
+        });
+    }
+}
+
+#[test]
+fn slice_rchunks_exact_mut() {
+    let mut s: Vec<_> = (0..10).collect();
+    let mut v: Vec<_> = s.clone();
+    for len in 1..s.len() + 2 {
+        let expected: Vec<_> = v.rchunks_exact_mut(len).collect();
+        map_triples(expected.len() + 1, |i, j, k| {
+            Split::forward(s.par_rchunks_exact_mut(len), i, j, k, &expected);
+            Split::reverse(s.par_rchunks_exact_mut(len), i, j, k, &expected);
+        });
+    }
+}
+
+#[test]
+fn slice_windows() {
+    let s: Vec<_> = (0..10).collect();
+    let v: Vec<_> = s.windows(2).collect();
+    check(&v, || s.par_windows(2));
+}
+
+#[test]
+fn vec() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || v.clone());
+}
+
+// **** Adaptors ****
+
+#[test]
+fn chain() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || (0..5).into_par_iter().chain(5..10));
+}
+
+#[test]
+fn cloned() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || v.par_iter().cloned());
+}
+
+#[test]
+fn copied() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || v.par_iter().copied());
+}
+
+#[test]
+fn enumerate() {
+    let v: Vec<_> = (0..10).enumerate().collect();
+    check(&v, || (0..10).into_par_iter().enumerate());
+}
+
+#[test]
+fn step_by() {
+    let v: Vec<_> = (0..10).step_by(2).collect();
+    check(&v, || (0..10).into_par_iter().step_by(2))
+}
+
+#[test]
+fn step_by_unaligned() {
+    let v: Vec<_> = (0..10).step_by(3).collect();
+    check(&v, || (0..10).into_par_iter().step_by(3))
+}
+
+#[test]
+fn inspect() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || (0..10).into_par_iter().inspect(|_| ()));
+}
+
+#[test]
+fn update() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || (0..10).into_par_iter().update(|_| ()));
+}
+
+#[test]
+fn interleave() {
+    let v = [0, 10, 1, 11, 2, 12, 3, 4];
+    check(&v, || (0..5).into_par_iter().interleave(10..13));
+    check(&v[..6], || (0..3).into_par_iter().interleave(10..13));
+
+    let v = [0, 10, 1, 11, 2, 12, 13, 14];
+    check(&v, || (0..3).into_par_iter().interleave(10..15));
+}
+
+#[test]
+fn intersperse() {
+    let v = [0, -1, 1, -1, 2, -1, 3, -1, 4];
+    check(&v, || (0..5).into_par_iter().intersperse(-1));
+}
+
+#[test]
+fn chunks() {
+    let s: Vec<_> = (0..10).collect();
+    let v: Vec<_> = s.chunks(2).map(|c| c.to_vec()).collect();
+    check(&v, || s.par_iter().cloned().chunks(2));
+}
+
+#[test]
+fn map() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || v.par_iter().map(Clone::clone));
+}
+
+#[test]
+fn map_with() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || v.par_iter().map_with(vec![0], |_, &x| x));
+}
+
+#[test]
+fn map_init() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || v.par_iter().map_init(|| vec![0], |_, &x| x));
+}
+
+#[test]
+fn panic_fuse() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || (0..10).into_par_iter().panic_fuse());
+}
+
+#[test]
+fn rev() {
+    let v: Vec<_> = (0..10).rev().collect();
+    check(&v, || (0..10).into_par_iter().rev());
+}
+
+#[test]
+fn with_max_len() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || (0..10).into_par_iter().with_max_len(1));
+}
+
+#[test]
+fn with_min_len() {
+    let v: Vec<_> = (0..10).collect();
+    check(&v, || (0..10).into_par_iter().with_min_len(1));
+}
+
+#[test]
+fn zip() {
+    let v: Vec<_> = (0..10).zip(10..20).collect();
+    check(&v, || (0..10).into_par_iter().zip(10..20));
+    check(&v[..5], || (0..5).into_par_iter().zip(10..20));
+    check(&v[..5], || (0..10).into_par_iter().zip(10..15));
+}
diff --git a/third_party/rust/rayon/tests/sort-panic-safe.rs b/third_party/rust/rayon/tests/sort-panic-safe.rs
new file mode 100644
index 0000000000..00a973106f
--- /dev/null
+++ b/third_party/rust/rayon/tests/sort-panic-safe.rs
@@ -0,0 +1,162 @@
+use rand::distributions::Uniform;
+use rand::{thread_rng, Rng};
+use rayon::prelude::*;
+use std::cell::Cell;
+use std::cmp::{self, Ordering};
+use std::panic;
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::Ordering::Relaxed;
+use std::thread;
+
+static VERSIONS: AtomicUsize = AtomicUsize::new(0);
+
+lazy_static::lazy_static! {
+    static ref DROP_COUNTS: Vec<AtomicUsize> = (0..20_000).map(|_| AtomicUsize::new(0)).collect();
+}
+
+#[derive(Clone, Eq)]
+struct DropCounter {
+    x: u32,
+    id: usize,
+    version: Cell<usize>,
+}
+
+impl PartialEq for DropCounter {
+    fn eq(&self, other: &Self) -> bool {
+        self.partial_cmp(other) == Some(Ordering::Equal)
+    }
+}
+
+impl PartialOrd for DropCounter {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.version.set(self.version.get() + 1);
+        other.version.set(other.version.get() + 1);
+        VERSIONS.fetch_add(2, Relaxed);
+        self.x.partial_cmp(&other.x)
+    }
+}
+
+impl Ord for DropCounter {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.partial_cmp(other).unwrap()
+    }
+}
+
+impl Drop for DropCounter {
+    fn drop(&mut self) {
+        DROP_COUNTS[self.id].fetch_add(1, Relaxed);
+        VERSIONS.fetch_sub(self.version.get(), Relaxed);
+    }
+}
+
+macro_rules! test {
+    ($input:ident, $func:ident) => {
+        let len = $input.len();
+
+        // Work out the total number of comparisons required to sort
+        // this array...
+        let count = AtomicUsize::new(0);
+        $input.to_owned().$func(|a, b| {
+            count.fetch_add(1, Relaxed);
+            a.cmp(b)
+        });
+
+        let mut panic_countdown = count.load(Relaxed);
+        let step = if len <= 100 {
+            1
+        } else {
+            cmp::max(1, panic_countdown / 10)
+        };
+
+        // ... and then panic after each `step` comparisons.
+        loop {
+            // Refresh the counters.
+            VERSIONS.store(0, Relaxed);
+            for i in 0..len {
+                DROP_COUNTS[i].store(0, Relaxed);
+            }
+
+            let v = $input.to_owned();
+            let _ = thread::spawn(move || {
+                let mut v = v;
+                let panic_countdown = AtomicUsize::new(panic_countdown);
+                v.$func(|a, b| {
+                    if panic_countdown.fetch_sub(1, Relaxed) == 1 {
+                        SILENCE_PANIC.with(|s| s.set(true));
+                        panic!();
+                    }
+                    a.cmp(b)
+                })
+            })
+            .join();
+
+            // Check that the number of things dropped is exactly
+            // what we expect (i.e. the contents of `v`).
+            for (i, c) in DROP_COUNTS.iter().enumerate().take(len) {
+                let count = c.load(Relaxed);
+                assert!(
+                    count == 1,
+                    "found drop count == {} for i == {}, len == {}",
+                    count,
+                    i,
+                    len
+                );
+            }
+
+            // Check that the most recent versions of values were dropped.
+            assert_eq!(VERSIONS.load(Relaxed), 0);
+
+            if panic_countdown < step {
+                break;
+            }
+            panic_countdown -= step;
+        }
+    };
+}
+
+thread_local!(static SILENCE_PANIC: Cell<bool> = Cell::new(false));
+
+#[test]
+fn sort_panic_safe() {
+    let prev = panic::take_hook();
+    panic::set_hook(Box::new(move |info| {
+        if !SILENCE_PANIC.with(Cell::get) {
+            prev(info);
+        }
+    }));
+
+    for &len in &[1, 2, 3, 4, 5, 10, 20, 100, 500, 5_000, 20_000] {
+        let len_dist = Uniform::new(0, len);
+        for &modulus in &[5, 30, 1_000, 20_000] {
+            for &has_runs in &[false, true] {
+                let mut rng = thread_rng();
+                let mut input = (0..len)
+                    .map(|id| DropCounter {
+                        x: rng.gen_range(0..modulus),
+                        id,
+                        version: Cell::new(0),
+                    })
+                    .collect::<Vec<_>>();
+
+                if has_runs {
+                    for c in &mut input {
+                        c.x = c.id as u32;
+                    }
+
+                    for _ in 0..5 {
+                        let a = rng.sample(&len_dist);
+                        let b = rng.sample(&len_dist);
+                        if a < b {
+                            input[a..b].reverse();
+                        } else {
+                            input.swap(a, b);
+                        }
+                    }
+                }
+
+                test!(input, par_sort_by);
+                test!(input, par_sort_unstable_by);
+            }
+        }
+    }
+}
diff --git a/third_party/rust/rayon/tests/str.rs b/third_party/rust/rayon/tests/str.rs
new file mode 100644
index 0000000000..f73a261148
--- /dev/null
+++ b/third_party/rust/rayon/tests/str.rs
@@ -0,0 +1,134 @@
+use rand::distributions::Standard;
+use rand::{Rng, SeedableRng};
+use rand_xorshift::XorShiftRng;
+use rayon::prelude::*;
+
+fn seeded_rng() -> XorShiftRng {
+    let mut seed = <XorShiftRng as SeedableRng>::Seed::default();
+    (0..).zip(seed.as_mut()).for_each(|(i, x)| *x = i);
+    XorShiftRng::from_seed(seed)
+}
+
+#[test]
+pub fn execute_strings() {
+    let rng = seeded_rng();
+    let s: String = rng.sample_iter::<char, _>(&Standard).take(1024).collect();
+
+    let par_chars: String = s.par_chars().collect();
+    assert_eq!(s, par_chars);
+
+    let par_even: String = s.par_chars().filter(|&c| (c as u32) & 1 == 0).collect();
+    let ser_even: String = s.chars().filter(|&c| (c as u32) & 1 == 0).collect();
+    assert_eq!(par_even, ser_even);
+
+    // test `FromParallelIterator<&char> for String`
+    let vchars: Vec<char> = s.par_chars().collect();
+    let par_chars: String = vchars.par_iter().collect();
+    assert_eq!(s, par_chars);
+
+    let par_bytes: Vec<u8> = s.par_bytes().collect();
+    assert_eq!(s.as_bytes(), &*par_bytes);
+
+    let par_utf16: Vec<u16> = s.par_encode_utf16().collect();
+    let ser_utf16: Vec<u16> = s.encode_utf16().collect();
+    assert_eq!(par_utf16, ser_utf16);
+
+    let par_charind: Vec<_> = s.par_char_indices().collect();
+    let ser_charind: Vec<_> = s.char_indices().collect();
+    assert_eq!(par_charind, ser_charind);
+}
+
+#[test]
+pub fn execute_strings_split() {
+    // char testcases from examples in `str::split` etc.,
+    // plus a large self-test for good measure.
+    let tests = vec![
+        ("Mary had a little lamb", ' '),
+        ("", 'X'),
+        ("lionXXtigerXleopard", 'X'),
+        ("||||a||b|c", '|'),
+        ("(///)", '/'),
+        ("010", '0'),
+        ("    a  b c", ' '),
+        ("A.B.", '.'),
+        ("A..B..", '.'),
+        ("foo\r\nbar\n\nbaz\n", '\n'),
+        ("foo\nbar\n\r\nbaz", '\n'),
+        ("A few words", ' '),
+        (" Mary   had\ta\u{2009}little  \n\t lamb", ' '),
+        (include_str!("str.rs"), ' '),
+    ];
+
+    for &(string, separator) in &tests {
+        let serial: Vec<_> = string.split(separator).collect();
+        let parallel: Vec<_> = string.par_split(separator).collect();
+        assert_eq!(serial, parallel);
+
+        let pattern: &[char] = &['\u{0}', separator, '\u{1F980}'];
+        let serial: Vec<_> = string.split(pattern).collect();
+        let parallel: Vec<_> = string.par_split(pattern).collect();
+        assert_eq!(serial, parallel);
+
+        let serial_fn: Vec<_> = string.split(|c| c == separator).collect();
+        let parallel_fn: Vec<_> = string.par_split(|c| c == separator).collect();
+        assert_eq!(serial_fn, parallel_fn);
+    }
+
+    for &(string, separator) in &tests {
+        let serial: Vec<_> = string.split_terminator(separator).collect();
+        let parallel: Vec<_> = string.par_split_terminator(separator).collect();
+        assert_eq!(serial, parallel);
+
+        let pattern: &[char] = &['\u{0}', separator, '\u{1F980}'];
+        let serial: Vec<_> = string.split_terminator(pattern).collect();
+        let parallel: Vec<_> = string.par_split_terminator(pattern).collect();
+        assert_eq!(serial, parallel);
+
+        let serial: Vec<_> = string.split_terminator(|c| c == separator).collect();
+        let parallel: Vec<_> = string.par_split_terminator(|c| c == separator).collect();
+        assert_eq!(serial, parallel);
+    }
+
+    for &(string, _) in &tests {
+        let serial: Vec<_> = string.lines().collect();
+        let parallel: Vec<_> = string.par_lines().collect();
+        assert_eq!(serial, parallel);
+    }
+
+    for &(string, _) in &tests {
+        let serial: Vec<_> = string.split_whitespace().collect();
+        let parallel: Vec<_> = string.par_split_whitespace().collect();
+        assert_eq!(serial, parallel);
+    }
+
+    // try matching separators too!
+    for &(string, separator) in &tests {
+        let serial: Vec<_> = string.matches(separator).collect();
+        let parallel: Vec<_> = string.par_matches(separator).collect();
+        assert_eq!(serial, parallel);
+
+        let pattern: &[char] = &['\u{0}', separator, '\u{1F980}'];
+        let serial: Vec<_> = string.matches(pattern).collect();
+        let parallel: Vec<_> = string.par_matches(pattern).collect();
+        assert_eq!(serial, parallel);
+
+        let serial_fn: Vec<_> = string.matches(|c| c == separator).collect();
+        let parallel_fn: Vec<_> = string.par_matches(|c| c == separator).collect();
+        assert_eq!(serial_fn, parallel_fn);
+    }
+
+    for &(string, separator) in &tests {
+        let serial: Vec<_> = string.match_indices(separator).collect();
+        let parallel: Vec<_> = string.par_match_indices(separator).collect();
+        assert_eq!(serial, parallel);
+
+        let pattern: &[char] = &['\u{0}', separator, '\u{1F980}'];
+        let serial: Vec<_> = string.match_indices(pattern).collect();
+        let parallel: Vec<_> = string.par_match_indices(pattern).collect();
+        assert_eq!(serial, parallel);
+
+        let serial_fn: Vec<_> = string.match_indices(|c| c == separator).collect();
+        let parallel_fn: Vec<_> = string.par_match_indices(|c| c == separator).collect();
+        assert_eq!(serial_fn, parallel_fn);
+    }
+}