122 lines
3.0 KiB
Rust
122 lines
3.0 KiB
Rust
//@ run-pass
|
|
//@ edition:2024
|
|
//@ compile-flags: -Z validate-mir -Zunstable-options
|
|
|
|
#![feature(let_chains)]
|
|
|
|
use std::cell::RefCell;
|
|
use std::convert::TryInto;
|
|
|
|
#[derive(Default)]
|
|
struct DropOrderCollector(RefCell<Vec<u32>>);
|
|
|
|
struct LoudDrop<'a>(&'a DropOrderCollector, u32);
|
|
|
|
impl Drop for LoudDrop<'_> {
|
|
fn drop(&mut self) {
|
|
println!("{}", self.1);
|
|
self.0.0.borrow_mut().push(self.1);
|
|
}
|
|
}
|
|
|
|
impl DropOrderCollector {
|
|
fn option_loud_drop(&self, n: u32) -> Option<LoudDrop> {
|
|
Some(LoudDrop(self, n))
|
|
}
|
|
|
|
fn print(&self, n: u32) {
|
|
println!("{}", n);
|
|
self.0.borrow_mut().push(n)
|
|
}
|
|
|
|
fn assert_sorted(self) {
|
|
assert!(
|
|
self.0
|
|
.into_inner()
|
|
.into_iter()
|
|
.enumerate()
|
|
.all(|(idx, item)| idx + 1 == item.try_into().unwrap())
|
|
);
|
|
}
|
|
|
|
fn if_let(&self) {
|
|
if let None = self.option_loud_drop(1) {
|
|
unreachable!();
|
|
} else {
|
|
self.print(2);
|
|
}
|
|
|
|
if let Some(_) = self.option_loud_drop(4) {
|
|
self.print(3);
|
|
}
|
|
|
|
if let Some(_d) = self.option_loud_drop(6) {
|
|
self.print(5);
|
|
}
|
|
}
|
|
|
|
fn let_chain(&self) {
|
|
// take the "then" branch
|
|
if self.option_loud_drop(1).is_some() // 1
|
|
&& self.option_loud_drop(2).is_some() // 2
|
|
&& let Some(_d) = self.option_loud_drop(4)
|
|
// 4
|
|
{
|
|
self.print(3); // 3
|
|
}
|
|
|
|
// take the "else" branch
|
|
if self.option_loud_drop(5).is_some() // 1
|
|
&& self.option_loud_drop(6).is_some() // 2
|
|
&& let None = self.option_loud_drop(7)
|
|
// 3
|
|
{
|
|
unreachable!();
|
|
} else {
|
|
self.print(8); // 4
|
|
}
|
|
|
|
// let exprs interspersed
|
|
if self.option_loud_drop(9).is_some() // 1
|
|
&& let Some(_d) = self.option_loud_drop(13) // 5
|
|
&& self.option_loud_drop(10).is_some() // 2
|
|
&& let Some(_e) = self.option_loud_drop(12)
|
|
// 4
|
|
{
|
|
self.print(11); // 3
|
|
}
|
|
|
|
// let exprs first
|
|
if let Some(_d) = self.option_loud_drop(18) // 5
|
|
&& let Some(_e) = self.option_loud_drop(17) // 4
|
|
&& self.option_loud_drop(14).is_some() // 1
|
|
&& self.option_loud_drop(15).is_some()
|
|
// 2
|
|
{
|
|
self.print(16); // 3
|
|
}
|
|
|
|
// let exprs last
|
|
if self.option_loud_drop(19).is_some() // 1
|
|
&& self.option_loud_drop(20).is_some() // 2
|
|
&& let Some(_d) = self.option_loud_drop(23) // 5
|
|
&& let Some(_e) = self.option_loud_drop(22)
|
|
// 4
|
|
{
|
|
self.print(21); // 3
|
|
}
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
println!("-- if let --");
|
|
let collector = DropOrderCollector::default();
|
|
collector.if_let();
|
|
collector.assert_sorted();
|
|
|
|
println!("-- let chain --");
|
|
let collector = DropOrderCollector::default();
|
|
collector.let_chain();
|
|
collector.assert_sorted();
|
|
}
|