Rollup merge of rust-lang#62193 - matthewjasper:dynamic-drop-async, r=Centril

Create async version of the dynamic-drop test

Some of the tests in dynamic-drop have been cut:
* The tests that are just simpler versions of other tests - these tests are already fairly slow due to all of the unwinding and async functions have more control flow paths than normal functions.
* The union test - it's for an unstable feature that has an RFC to remove it.
* The generator test - there aren't async generators yet.
* The tests that show values being leaked - these can be added once the issue is fixed.

r? @Centril
cc  rust-lang#62121 @cramertj

Author: Centril

src/test/run-pass/drop/dynamic-drop-async.rs

@@ -0,0 +1,328 @@
+// Test that values are not leaked in async functions, even in the cases where:
+// * Dropping one of the values panics while running the future.
+// * The future is dropped at one of its suspend points.
+// * Dropping one of the values panics while dropping the future.
+
+// run-pass
+// edition:2018
+// ignore-wasm32-bare compiled with panic=abort by default
+
+#![allow(unused_assignments)]
+#![allow(unused_variables)]
+#![feature(slice_patterns)]
+#![feature(async_await)]
+
+use std::{
+    cell::{Cell, RefCell},
+    future::Future,
+    marker::Unpin,
+    panic,
+    pin::Pin,
+    ptr,
+    rc::Rc,
+    task::{Context, Poll, RawWaker, RawWakerVTable, Waker},
+    usize,
+};
+
+struct InjectedFailure;
+
+struct Defer<T> {
+    ready: bool,
+    value: Option<T>,
+}
+
+impl<T: Unpin> Future for Defer<T> {
+    type Output = T;
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
+        if self.ready {
+            Poll::Ready(self.value.take().unwrap())
+        } else {
+            self.ready = true;
+            Poll::Pending
+        }
+    }
+}
+
+/// Allocator tracks the creation and destruction of `Ptr`s.
+/// The `failing_op`-th operation will panic.
+struct Allocator {
+    data: RefCell<Vec<bool>>,
+    failing_op: usize,
+    cur_ops: Cell<usize>,
+}
+
+impl panic::UnwindSafe for Allocator {}
+impl panic::RefUnwindSafe for Allocator {}
+
+impl Drop for Allocator {
+    fn drop(&mut self) {
+        let data = self.data.borrow();
+        if data.iter().any(|d| *d) {
+            panic!("missing free: {:?}", data);
+        }
+    }
+}
+
+impl Allocator {
+    fn new(failing_op: usize) -> Self {
+        Allocator { failing_op, cur_ops: Cell::new(0), data: RefCell::new(vec![]) }
+    }
+    fn alloc(&self) -> impl Future<Output = Ptr<'_>> + '_ {
+        self.fallible_operation();
+
+        let mut data = self.data.borrow_mut();
+
+        let addr = data.len();
+        data.push(true);
+        Defer { ready: false, value: Some(Ptr(addr, self)) }
+    }
+    fn fallible_operation(&self) {
+        self.cur_ops.set(self.cur_ops.get() + 1);
+
+        if self.cur_ops.get() == self.failing_op {
+            panic!(InjectedFailure);
+        }
+    }
+}
+
+// Type that tracks whether it was dropped and can panic when it's created or
+// destroyed.
+struct Ptr<'a>(usize, &'a Allocator);
+impl<'a> Drop for Ptr<'a> {
+    fn drop(&mut self) {
+        match self.1.data.borrow_mut()[self.0] {
+            false => panic!("double free at index {:?}", self.0),
+            ref mut d => *d = false,
+        }
+
+        self.1.fallible_operation();
+    }
+}
+
+async fn dynamic_init(a: Rc<Allocator>, c: bool) {
+    let _x;
+    if c {
+        _x = Some(a.alloc().await);
+    }
+}
+
+async fn dynamic_drop(a: Rc<Allocator>, c: bool) {
+    let x = a.alloc().await;
+    if c {
+        Some(x)
+    } else {
+        None
+    };
+}
+
+struct TwoPtrs<'a>(Ptr<'a>, Ptr<'a>);
+async fn struct_dynamic_drop(a: Rc<Allocator>, c0: bool, c1: bool, c: bool) {
+    for i in 0..2 {
+        let x;
+        let y;
+        if (c0 && i == 0) || (c1 && i == 1) {
+            x = (a.alloc().await, a.alloc().await, a.alloc().await);
+            y = TwoPtrs(a.alloc().await, a.alloc().await);
+            if c {
+                drop(x.1);
+                a.alloc().await;
+                drop(y.0);
+                a.alloc().await;
+            }
+        }
+    }
+}
+
+async fn field_assignment(a: Rc<Allocator>, c0: bool) {
+    let mut x = (TwoPtrs(a.alloc().await, a.alloc().await), a.alloc().await);
+
+    x.1 = a.alloc().await;
+    x.1 = a.alloc().await;
+
+    let f = (x.0).0;
+    a.alloc().await;
+    if c0 {
+        (x.0).0 = f;
+    }
+    a.alloc().await;
+}
+
+async fn assignment(a: Rc<Allocator>, c0: bool, c1: bool) {
+    let mut _v = a.alloc().await;
+    let mut _w = a.alloc().await;
+    if c0 {
+        drop(_v);
+    }
+    _v = _w;
+    if c1 {
+        _w = a.alloc().await;
+    }
+}
+
+async fn array_simple(a: Rc<Allocator>) {
+    let _x = [a.alloc().await, a.alloc().await, a.alloc().await, a.alloc().await];
+}
+
+async fn vec_simple(a: Rc<Allocator>) {
+    let _x = vec![a.alloc().await, a.alloc().await, a.alloc().await, a.alloc().await];
+}
+
+async fn mixed_drop_and_nondrop(a: Rc<Allocator>) {
+    // check that destructor panics handle drop
+    // and non-drop blocks in the same scope correctly.
+    //
+    // Surprisingly enough, this used to not work.
+    let (x, y, z);
+    x = a.alloc().await;
+    y = 5;
+    z = a.alloc().await;
+}
+
+#[allow(unreachable_code)]
+async fn vec_unreachable(a: Rc<Allocator>) {
+    let _x = vec![a.alloc().await, a.alloc().await, a.alloc().await, return];
+}
+
+async fn slice_pattern_one_of(a: Rc<Allocator>, i: usize) {
+    let array = [a.alloc().await, a.alloc().await, a.alloc().await, a.alloc().await];
+    let _x = match i {
+        0 => {
+            let [a, ..] = array;
+            a
+        }
+        1 => {
+            let [_, a, ..] = array;
+            a
+        }
+        2 => {
+            let [_, _, a, _] = array;
+            a
+        }
+        3 => {
+            let [_, _, _, a] = array;
+            a
+        }
+        _ => panic!("unmatched"),
+    };
+    a.alloc().await;
+}
+
+async fn subslice_pattern_from_end_with_drop(a: Rc<Allocator>, arg: bool, arg2: bool) {
+    let arr = [a.alloc().await, a.alloc().await, a.alloc().await, a.alloc().await, a.alloc().await];
+    if arg2 {
+        drop(arr);
+        return;
+    }
+
+    if arg {
+        let [.., _x, _] = arr;
+    } else {
+        let [_, _y..] = arr;
+    }
+    a.alloc().await;
+}
+
+async fn subslice_pattern_reassign(a: Rc<Allocator>) {
+    let mut ar = [a.alloc().await, a.alloc().await, a.alloc().await];
+    let [_, _, _x] = ar;
+    ar = [a.alloc().await, a.alloc().await, a.alloc().await];
+    let [_, _y..] = ar;
+    a.alloc().await;
+}
+
+fn run_test<F, G>(cx: &mut Context<'_>, ref f: F)
+where
+    F: Fn(Rc<Allocator>) -> G,
+    G: Future<Output = ()>,
+{
+    for polls in 0.. {
+        // Run without any panics to find which operations happen after the
+        // penultimate `poll`.
+        let first_alloc = Rc::new(Allocator::new(usize::MAX));
+        let mut fut = Box::pin(f(first_alloc.clone()));
+        let mut ops_before_last_poll = 0;
+        let mut completed = false;
+        for _ in 0..polls {
+            ops_before_last_poll = first_alloc.cur_ops.get();
+            if let Poll::Ready(()) = fut.as_mut().poll(cx) {
+                completed = true;
+            }
+        }
+        drop(fut);
+
+        // Start at `ops_before_last_poll` so that we will always be able to
+        // `poll` the expected number of times.
+        for failing_op in ops_before_last_poll..first_alloc.cur_ops.get() {
+            let alloc = Rc::new(Allocator::new(failing_op + 1));
+            let f = &f;
+            let cx = &mut *cx;
+            let result = panic::catch_unwind(panic::AssertUnwindSafe(move || {
+                let mut fut = Box::pin(f(alloc));
+                for _ in 0..polls {
+                    let _ = fut.as_mut().poll(cx);
+                }
+                drop(fut);
+            }));
+            match result {
+                Ok(..) => panic!("test executed more ops on first call"),
+                Err(e) => {
+                    if e.downcast_ref::<InjectedFailure>().is_none() {
+                        panic::resume_unwind(e);
+                    }
+                }
+            }
+        }
+
+        if completed {
+            break;
+        }
+    }
+}
+
+fn clone_waker(data: *const ()) -> RawWaker {
+    RawWaker::new(data, &RawWakerVTable::new(clone_waker, drop, drop, drop))
+}
+
+fn main() {
+    let waker = unsafe { Waker::from_raw(clone_waker(ptr::null())) };
+    let context = &mut Context::from_waker(&waker);
+
+    run_test(context, |a| dynamic_init(a, false));
+    run_test(context, |a| dynamic_init(a, true));
+    run_test(context, |a| dynamic_drop(a, false));
+    run_test(context, |a| dynamic_drop(a, true));
+
+    run_test(context, |a| assignment(a, false, false));
+    run_test(context, |a| assignment(a, false, true));
+    run_test(context, |a| assignment(a, true, false));
+    run_test(context, |a| assignment(a, true, true));
+
+    run_test(context, |a| array_simple(a));
+    run_test(context, |a| vec_simple(a));
+    run_test(context, |a| vec_unreachable(a));
+
+    run_test(context, |a| struct_dynamic_drop(a, false, false, false));
+    run_test(context, |a| struct_dynamic_drop(a, false, false, true));
+    run_test(context, |a| struct_dynamic_drop(a, false, true, false));
+    run_test(context, |a| struct_dynamic_drop(a, false, true, true));
+    run_test(context, |a| struct_dynamic_drop(a, true, false, false));
+    run_test(context, |a| struct_dynamic_drop(a, true, false, true));
+    run_test(context, |a| struct_dynamic_drop(a, true, true, false));
+    run_test(context, |a| struct_dynamic_drop(a, true, true, true));
+
+    run_test(context, |a| field_assignment(a, false));
+    run_test(context, |a| field_assignment(a, true));
+
+    run_test(context, |a| mixed_drop_and_nondrop(a));
+
+    run_test(context, |a| slice_pattern_one_of(a, 0));
+    run_test(context, |a| slice_pattern_one_of(a, 1));
+    run_test(context, |a| slice_pattern_one_of(a, 2));
+    run_test(context, |a| slice_pattern_one_of(a, 3));
+
+    run_test(context, |a| subslice_pattern_from_end_with_drop(a, true, true));
+    run_test(context, |a| subslice_pattern_from_end_with_drop(a, true, false));
+    run_test(context, |a| subslice_pattern_from_end_with_drop(a, false, true));
+    run_test(context, |a| subslice_pattern_from_end_with_drop(a, false, false));
+    run_test(context, |a| subslice_pattern_reassign(a));
+}