test drop order for parameters when a future is dropped part-way thro…

…ugh execution

src/test/ui/async-await/drop-order/drop-order-when-cancelled.rs

@@ -0,0 +1,307 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+#![allow(unused_variables)]
+#![feature(async_await)]
+
+// 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 is cancelled.
+// This file is mostly copy-pasted from drop-order-for-async-fn-parameters.rs
+
+extern crate arc_wake;
+
+use arc_wake::ArcWake;
+use std::cell::RefCell;
+use std::future::Future;
+use std::marker::PhantomData;
+use std::pin::Pin;
+use std::rc::Rc;
+use std::sync::Arc;
+use std::task::{Context, Poll};
+
+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));
+    }
+}
+
+struct NeverReady;
+
+impl Future for NeverReady {
+    type Output = ();
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
+        Poll::Pending
+    }
+}
+
+/// Check that unused bindings are dropped after the function is polled.
+async fn foo_async(x: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+    NeverReady.await;
+}
+
+fn foo_sync(x: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns are dropped after the function is polled.
+async fn bar_async(x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+    NeverReady.await;
+}
+
+fn bar_sync(x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns within more complex patterns are dropped after the function
+/// is polled.
+async fn baz_async((x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+    NeverReady.await;
+}
+
+fn baz_sync((x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore and unused bindings within and outwith more complex patterns are dropped
+/// after the function is polled.
+async fn foobar_async(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+    NeverReady.await;
+}
+
+fn foobar_sync(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+struct Foo;
+
+impl Foo {
+    /// Check that unused bindings are dropped after the method is polled.
+    async fn foo_async(x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn foo_sync(x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method is polled.
+    async fn bar_async(x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn bar_sync(x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// is polled.
+    async fn baz_async((x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn baz_sync((x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method is polled.
+    async fn foobar_async(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn foobar_sync(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+struct Bar<'a>(PhantomData<&'a ()>);
+
+impl<'a> Bar<'a> {
+    /// Check that unused bindings are dropped after the method with self is polled.
+    async fn foo_async(&'a self, x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn foo_sync(&'a self, x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method with self is polled.
+    async fn bar_async(&'a self, x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn bar_sync(&'a self, x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// with self is polled.
+    async fn baz_async(&'a self, (x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn baz_sync(&'a self, (x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method with self is polled.
+    async fn foobar_async(&'a self, x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn foobar_sync(&'a self, x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+fn assert_drop_order_after_cancel<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 _ = fut.as_mut().poll(&mut cx);
+
+    // Parameters are never dropped until the future completes.
+    assert_eq!(*actual_order.borrow(), vec![DropOrder::Function]);
+
+    drop(fut);
+
+    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_cancel(
+        |l| foo_async(D("x", l.clone()), D("_y", l.clone())),
+        |l| foo_sync(D("x", l.clone()), D("_y", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| bar_async(D("x", l.clone()), D("_", l.clone())),
+        |l| bar_sync(D("x", l.clone()), D("_", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| baz_async((D("x", l.clone()), D("_", l.clone()))),
+        |l| baz_sync((D("x", l.clone()), D("_", l.clone()))),
+    );
+    assert_drop_order_after_cancel(
+        |l| {
+            foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods w/out self (see doc comment on function for what it tests).
+    assert_drop_order_after_cancel(
+        |l| Foo::foo_async(D("x", l.clone()), D("_y", l.clone())),
+        |l| Foo::foo_sync(D("x", l.clone()), D("_y", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| Foo::bar_async(D("x", l.clone()), D("_", l.clone())),
+        |l| Foo::bar_sync(D("x", l.clone()), D("_", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| Foo::baz_async((D("x", l.clone()), D("_", l.clone()))),
+        |l| Foo::baz_sync((D("x", l.clone()), D("_", l.clone()))),
+    );
+    assert_drop_order_after_cancel(
+        |l| {
+            Foo::foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            Foo::foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods (see doc comment on function for what it tests).
+    let b = Bar(Default::default());
+    assert_drop_order_after_cancel(
+        |l| b.foo_async(D("x", l.clone()), D("_y", l.clone())),
+        |l| b.foo_sync(D("x", l.clone()), D("_y", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| b.bar_async(D("x", l.clone()), D("_", l.clone())),
+        |l| b.bar_sync(D("x", l.clone()), D("_", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| b.baz_async((D("x", l.clone()), D("_", l.clone()))),
+        |l| b.baz_sync((D("x", l.clone()), D("_", l.clone()))),
+    );
+    assert_drop_order_after_cancel(
+        |l| {
+            b.foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            b.foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+}