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// run-pass
#![feature(let_else)]
use std::fmt::Display;
use std::rc::Rc;
use std::sync::atomic::{AtomicU8, Ordering};
static TRACKER: AtomicU8 = AtomicU8::new(0);
#[derive(Default)]
struct Droppy {
inner: u32,
}
impl Drop for Droppy {
fn drop(&mut self) {
TRACKER.store(1, Ordering::Release);
println!("I've been dropped");
}
}
fn foo<'a>(x: &'a str) -> Result<impl Display + 'a, ()> {
Ok(x)
}
fn main() {
assert_eq!(TRACKER.load(Ordering::Acquire), 0);
let 0 = Droppy::default().inner else { return };
assert_eq!(TRACKER.load(Ordering::Acquire), 1);
println!("Should have dropped 👆");
{
// cf. https://github.com/rust-lang/rust/pull/99518#issuecomment-1191520030
struct Foo<'a>(&'a mut u32);
impl<'a> Drop for Foo<'a> {
fn drop(&mut self) {
*self.0 = 0;
}
}
let mut foo = 0;
let Foo(0) = Foo(&mut foo) else {
*&mut foo = 1;
todo!()
};
}
{
let x = String::from("Hey");
let Ok(s) = foo(&x) else { panic!() };
assert_eq!(s.to_string(), x);
}
{
// test let-else drops temps after statement
let rc = Rc::new(0);
let 0 = *rc.clone() else { unreachable!() };
Rc::try_unwrap(rc).unwrap();
}
{
let mut rc = Rc::new(0);
let mut i = 0;
loop {
if i > 3 {
break;
}
let 1 = *rc.clone() else {
if let Ok(v) = Rc::try_unwrap(rc) {
rc = Rc::new(v);
} else {
panic!()
}
i += 1;
continue
};
}
}
{
// test let-else drops temps before else block
// NOTE: this test has to be the last block in the `main`
// body.
let rc = Rc::new(0);
let 1 = *rc.clone() else {
Rc::try_unwrap(rc).unwrap();
return;
};
unreachable!();
}
}
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