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// aux-build:arc_wake.rs
// edition:2018
// run-pass
// revisions: default nomiropt
//[nomiropt]compile-flags: -Z mir-opt-level=0
#![allow(unused_variables)]
// Test the drop order for parameters relative to local variables and
// temporaries created in the tail return expression of the function
// body. In particular, check that this drop order is the same between
// an `async fn` and an ordinary `fn`. See #64512.
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())));
}
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