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#![warn(rust_2018_idioms, single_use_lifetimes)]
// Refs: https://doc.rust-lang.org/reference/destructors.html
use std::{cell::Cell, panic, pin::Pin, thread};
use pin_project_lite::pin_project;
struct D<'a>(&'a Cell<usize>, usize);
impl Drop for D<'_> {
fn drop(&mut self) {
if !thread::panicking() {
let old = self.0.replace(self.1);
assert_eq!(old, self.1 - 1);
}
}
}
pin_project! {
#[project = StructPinnedProj]
#[project_ref = StructPinnedProjRef]
#[project_replace = StructPinnedProjReplace]
struct StructPinned<'a> {
#[pin]
f1: D<'a>,
#[pin]
f2: D<'a>,
}
}
pin_project! {
#[project = StructUnpinnedProj]
#[project_ref = StructUnpinnedProjRef]
#[project_replace = StructUnpinnedProjReplace]
struct StructUnpinned<'a> {
f1: D<'a>,
f2: D<'a>,
}
}
pin_project! {
#[project_replace = EnumProjReplace]
enum Enum<'a> {
#[allow(dead_code)] // false positive that fixed in Rust 1.38
StructPinned {
#[pin]
f1: D<'a>,
#[pin]
f2: D<'a>,
},
#[allow(dead_code)] // false positive that fixed in Rust 1.38
StructUnpinned {
f1: D<'a>,
f2: D<'a>,
},
}
}
#[test]
fn struct_pinned() {
{
let c = Cell::new(0);
let _x = StructPinned { f1: D(&c, 1), f2: D(&c, 2) };
}
{
let c = Cell::new(0);
let mut x = StructPinned { f1: D(&c, 1), f2: D(&c, 2) };
let y = Pin::new(&mut x);
let _z = y.project_replace(StructPinned { f1: D(&c, 3), f2: D(&c, 4) });
}
}
#[test]
fn struct_unpinned() {
{
let c = Cell::new(0);
let _x = StructUnpinned { f1: D(&c, 1), f2: D(&c, 2) };
}
{
let c = Cell::new(0);
let mut x = StructUnpinned { f1: D(&c, 1), f2: D(&c, 2) };
let y = Pin::new(&mut x);
let _z = y.project_replace(StructUnpinned { f1: D(&c, 3), f2: D(&c, 4) });
}
}
#[test]
fn enum_struct() {
{
let c = Cell::new(0);
let _x = Enum::StructPinned { f1: D(&c, 1), f2: D(&c, 2) };
}
{
let c = Cell::new(0);
let mut x = Enum::StructPinned { f1: D(&c, 1), f2: D(&c, 2) };
let y = Pin::new(&mut x);
let _z = y.project_replace(Enum::StructPinned { f1: D(&c, 3), f2: D(&c, 4) });
}
{
let c = Cell::new(0);
let _x = Enum::StructUnpinned { f1: D(&c, 1), f2: D(&c, 2) };
}
{
let c = Cell::new(0);
let mut x = Enum::StructUnpinned { f1: D(&c, 1), f2: D(&c, 2) };
let y = Pin::new(&mut x);
let _z = y.project_replace(Enum::StructUnpinned { f1: D(&c, 3), f2: D(&c, 4) });
}
}
// https://github.com/rust-lang/rust/issues/47949
// https://github.com/taiki-e/pin-project/pull/194#discussion_r419098111
#[allow(clippy::many_single_char_names)]
#[test]
fn project_replace_panic() {
pin_project! {
#[project_replace = SProjReplace]
struct S<T, U> {
#[pin]
pinned: T,
unpinned: U,
}
}
struct D<'a>(&'a mut bool, bool);
impl Drop for D<'_> {
fn drop(&mut self) {
*self.0 = true;
if self.1 {
panic!();
}
}
}
let (mut a, mut b, mut c, mut d) = (false, false, false, false);
let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
let mut x = S { pinned: D(&mut a, true), unpinned: D(&mut b, false) };
let _y = Pin::new(&mut x)
.project_replace(S { pinned: D(&mut c, false), unpinned: D(&mut d, false) });
// Previous `x.pinned` was dropped and panicked when `project_replace` is
// called, so this is unreachable.
unreachable!();
}));
assert!(res.is_err());
assert!(a);
assert!(b);
assert!(c);
assert!(d);
let (mut a, mut b, mut c, mut d) = (false, false, false, false);
let res = panic::catch_unwind(panic::AssertUnwindSafe(|| {
let mut x = S { pinned: D(&mut a, false), unpinned: D(&mut b, true) };
{
let _y = Pin::new(&mut x)
.project_replace(S { pinned: D(&mut c, false), unpinned: D(&mut d, false) });
// `_y` (previous `x.unpinned`) live to the end of this scope, so
// this is not unreachable.
// unreachable!();
}
unreachable!();
}));
assert!(res.is_err());
assert!(a);
assert!(b);
assert!(c);
assert!(d);
}
|
