Add tests for by-ref binding

3 files changed, 289 insertions, 1 deletions

diff --git a/src/test/ui/async-await/drop-order-for-async-fn-parameters-by-ref-binding.rs b/src/test/ui/async-await/drop-order-for-async-fn-parameters-by-ref-binding.rs
new file mode 100644
index 00000000000..c2b59eecb99
--- /dev/null
+++ b/src/test/ui/async-await/drop-order-for-async-fn-parameters-by-ref-binding.rs
@@ -0,0 +1,271 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+#![allow(unused_variables)]
+#![feature(async_await, await_macro)]
+
+// 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::marker::PhantomData;
+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 that unused bindings are dropped after the function is polled.
+async fn foo_async(ref mut x: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn foo_sync(ref mut x: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns are dropped after the function is polled.
+async fn bar_async(ref mut x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn bar_sync(ref mut 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((ref mut x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn baz_sync((ref mut 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(ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn foobar_sync(ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _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(ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foo_sync(ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method is polled.
+    async fn bar_async(ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn bar_sync(ref mut 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((ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn baz_sync((ref mut 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(
+        ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foobar_sync(
+        ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _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, ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foo_sync(&'a self, ref mut x: D, ref mut _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, ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn bar_sync(&'a self, ref mut 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, (ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn baz_sync(&'a self, (ref mut 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, ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foobar_sync(
+        &'a self, ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+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 _ = fut.as_mut().poll(&mut cx);
+
+    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())));
+    assert_drop_order_after_poll(|l| bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |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_poll(|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_poll(|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_poll(|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_poll(
+        |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_poll(|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_poll(|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_poll(|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_poll(
+        |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()),
+            )
+        },
+    );
+}
diff --git a/src/test/ui/async-await/drop-order-locals-are-hidden.rs b/src/test/ui/async-await/drop-order-locals-are-hidden.rs
index 10dc5e27f6f..bcdb8878eb5 100644
--- a/src/test/ui/async-await/drop-order-locals-are-hidden.rs
+++ b/src/test/ui/async-await/drop-order-locals-are-hidden.rs
@@ -8,4 +8,9 @@ async fn foobar_async(x: u32, (a, _, _c): (u32, u32, u32), _: u32, _y: u32) {
     assert_eq!(__arg2, 4); //~ ERROR cannot find value `__arg2` in this scope [E0425]
 }
 
+async fn baz_async(ref mut x: u32, ref y: u32) {
+    assert_eq!(__arg0, 1); //~ ERROR cannot find value `__arg0` in this scope [E0425]
+    assert_eq!(__arg1, 2); //~ ERROR cannot find value `__arg1` in this scope [E0425]
+}
+
 fn main() {}
diff --git a/src/test/ui/async-await/drop-order-locals-are-hidden.stderr b/src/test/ui/async-await/drop-order-locals-are-hidden.stderr
index ca0da6b7c96..484e1f4f426 100644
--- a/src/test/ui/async-await/drop-order-locals-are-hidden.stderr
+++ b/src/test/ui/async-await/drop-order-locals-are-hidden.stderr
@@ -10,6 +10,18 @@ error[E0425]: cannot find value `__arg2` in this scope
 LL |     assert_eq!(__arg2, 4);
    |                ^^^^^^ not found in this scope
 
-error: aborting due to 2 previous errors
+error[E0425]: cannot find value `__arg0` in this scope
+  --> $DIR/drop-order-locals-are-hidden.rs:12:16
+   |
+LL |     assert_eq!(__arg0, 1);
+   |                ^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `__arg1` in this scope
+  --> $DIR/drop-order-locals-are-hidden.rs:13:16
+   |
+LL |     assert_eq!(__arg1, 2);
+   |                ^^^^^^ not found in this scope
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0425`.