From cf94bdc0742c13e2a0cac864c478b8626b266e1b Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:11:38 +0200
Subject: Merging upstream version 1.66.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 library/alloc/tests/autotraits.rs | 293 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 293 insertions(+)
 create mode 100644 library/alloc/tests/autotraits.rs

(limited to 'library/alloc/tests/autotraits.rs')

diff --git a/library/alloc/tests/autotraits.rs b/library/alloc/tests/autotraits.rs
new file mode 100644
index 000000000..8ff5f0abe
--- /dev/null
+++ b/library/alloc/tests/autotraits.rs
@@ -0,0 +1,293 @@
+fn require_sync<T: Sync>(_: T) {}
+fn require_send_sync<T: Send + Sync>(_: T) {}
+
+struct NotSend(*const ());
+unsafe impl Sync for NotSend {}
+
+#[test]
+fn test_btree_map() {
+    // Tests of this form are prone to https://github.com/rust-lang/rust/issues/64552.
+    //
+    // In theory the async block's future would be Send if the value we hold
+    // across the await point is Send, and Sync if the value we hold across the
+    // await point is Sync.
+    //
+    // We test autotraits in this convoluted way, instead of a straightforward
+    // `require_send_sync::<TypeIWantToTest>()`, because the interaction with
+    // generators exposes some current limitations in rustc's ability to prove a
+    // lifetime bound on the erased generator witness types. See the above link.
+    //
+    // A typical way this would surface in real code is:
+    //
+    //     fn spawn<T: Future + Send>(_: T) {}
+    //
+    //     async fn f() {
+    //         let map = BTreeMap::<u32, Box<dyn Send + Sync>>::new();
+    //         for _ in &map {
+    //             async {}.await;
+    //         }
+    //     }
+    //
+    //     fn main() {
+    //         spawn(f());
+    //     }
+    //
+    // where with some unintentionally overconstrained Send impls in liballoc's
+    // internals, the future might incorrectly not be Send even though every
+    // single type involved in the program is Send and Sync.
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::Iter<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    // Testing like this would not catch all issues that the above form catches.
+    require_send_sync(None::<alloc::collections::btree_map::Iter<'_, &u32, &u32>>);
+
+    require_sync(async {
+        let _v = None::<alloc::collections::btree_map::Iter<'_, u32, NotSend>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::BTreeMap<&u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<
+            alloc::collections::btree_map::DrainFilter<
+                '_,
+                &u32,
+                &u32,
+                fn(&&u32, &mut &u32) -> bool,
+            >,
+        >;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::Entry<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::IntoIter<&u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::IntoKeys<&u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::IntoValues<&u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::Iter<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::IterMut<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::Keys<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::OccupiedEntry<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::OccupiedError<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::Range<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::RangeMut<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::VacantEntry<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::Values<'_, &u32, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_map::ValuesMut<'_, &u32, &u32>>;
+        async {}.await;
+    });
+}
+
+#[test]
+fn test_btree_set() {
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::BTreeSet<&u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::Difference<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::DrainFilter<'_, &u32, fn(&&u32) -> bool>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::Intersection<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::IntoIter<&u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::Iter<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::Range<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::SymmetricDifference<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::btree_set::Union<'_, &u32>>;
+        async {}.await;
+    });
+}
+
+#[test]
+fn test_binary_heap() {
+    require_send_sync(async {
+        let _v = None::<alloc::collections::binary_heap::BinaryHeap<&u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::binary_heap::Drain<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::binary_heap::DrainSorted<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::binary_heap::IntoIter<&u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::binary_heap::IntoIterSorted<&u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::binary_heap::Iter<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::binary_heap::PeekMut<'_, &u32>>;
+        async {}.await;
+    });
+}
+
+#[test]
+fn test_linked_list() {
+    require_send_sync(async {
+        let _v = None::<alloc::collections::linked_list::Cursor<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::linked_list::CursorMut<'_, &u32>>;
+        async {}.await;
+    });
+
+    // FIXME
+    /*
+    require_send_sync(async {
+        let _v =
+            None::<alloc::collections::linked_list::DrainFilter<'_, &u32, fn(&mut &u32) -> bool>>;
+        async {}.await;
+    });
+    */
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::linked_list::IntoIter<&u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::linked_list::Iter<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::linked_list::IterMut<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::linked_list::LinkedList<&u32>>;
+        async {}.await;
+    });
+}
+
+#[test]
+fn test_vec_deque() {
+    require_send_sync(async {
+        let _v = None::<alloc::collections::vec_deque::Drain<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::vec_deque::IntoIter<&u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::vec_deque::Iter<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::vec_deque::IterMut<'_, &u32>>;
+        async {}.await;
+    });
+
+    require_send_sync(async {
+        let _v = None::<alloc::collections::vec_deque::VecDeque<&u32>>;
+        async {}.await;
+    });
+}
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