add test for drop order of temporary in tail return expression
diff --git a/src/test/ui/async-await/drop-order/drop-order-for-temporary-in-tail-return-expr.rs b/src/test/ui/async-await/drop-order/drop-order-for-temporary-in-tail-return-expr.rs
new file mode 100644
index 0000000..e250506
--- /dev/null
+++ b/src/test/ui/async-await/drop-order/drop-order-for-temporary-in-tail-return-expr.rs
@@ -0,0 +1,94 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+#![allow(unused_variables)]
+
+// Test that the drop order for parameters in a fn and async fn matches up. Also test that
+// parameters (used or unused) are not dropped until the async fn completes execution.
+// See also #54716.
+
+extern crate arc_wake;
+
+use arc_wake::ArcWake;
+use std::cell::RefCell;
+use std::future::Future;
+use std::sync::Arc;
+use std::rc::Rc;
+use std::task::Context;
+
+struct EmptyWaker;
+
+impl ArcWake for EmptyWaker {
+ fn wake(self: Arc<Self>) {}
+}
+
+#[derive(Debug, Eq, PartialEq)]
+enum DropOrder {
+ Function,
+ Val(&'static str),
+}
+
+type DropOrderListPtr = Rc<RefCell<Vec<DropOrder>>>;
+
+struct D(&'static str, DropOrderListPtr);
+
+impl Drop for D {
+ fn drop(&mut self) {
+ self.1.borrow_mut().push(DropOrder::Val(self.0));
+ }
+}
+
+/// Check drop order of temporary "temp" as compared to x, y, and z.
+///
+/// Expected order:
+/// - z
+/// - temp
+/// - y
+/// - x
+async fn foo_async(x: D, _y: D) {
+ let l = x.1.clone();
+ let z = D("z", l.clone());
+ l.borrow_mut().push(DropOrder::Function);
+ helper_async(&D("temp", l)).await
+}
+
+async fn helper_async(v: &D) { }
+
+fn foo_sync(x: D, _y: D) {
+ let l = x.1.clone();
+ let z = D("z", l.clone());
+ l.borrow_mut().push(DropOrder::Function);
+ helper_sync(&D("temp", l))
+}
+
+fn helper_sync(v: &D) { }
+
+fn assert_drop_order_after_poll<Fut: Future<Output = ()>>(
+ f: impl FnOnce(DropOrderListPtr) -> Fut,
+ g: impl FnOnce(DropOrderListPtr),
+) {
+ let empty = Arc::new(EmptyWaker);
+ let waker = ArcWake::into_waker(empty);
+ let mut cx = Context::from_waker(&waker);
+
+ let actual_order = Rc::new(RefCell::new(Vec::new()));
+ let mut fut = Box::pin(f(actual_order.clone()));
+ let r = fut.as_mut().poll(&mut cx);
+
+ assert!(match r {
+ std::task::Poll::Ready(()) => true,
+ _ => false,
+ });
+
+ let expected_order = Rc::new(RefCell::new(Vec::new()));
+ g(expected_order.clone());
+
+ assert_eq!(*actual_order.borrow(), *expected_order.borrow());
+}
+
+fn main() {
+ // Free functions (see doc comment on function for what it tests).
+ assert_drop_order_after_poll(|l| foo_async(D("x", l.clone()), D("_y", l.clone())),
+ |l| foo_sync(D("x", l.clone()), D("_y", l.clone())));
+}
