rust/tests/ui/let_unit.rs
2017-10-03 12:07:24 +02:00

50 lines
988 B
Rust

#![warn(let_unit_value)]
#![allow(unused_variables)]
macro_rules! let_and_return {
($n:expr) => {{
let ret = $n;
}}
}
fn main() {
let _x = println!("x");
let _y = 1; // this is fine
let _z = ((), 1); // this as well
if true {
let _a = ();
}
consume_units_with_for_loop(); // should be fine as well
let_and_return!(()) // should be fine
}
// Related to issue #1964
fn consume_units_with_for_loop() {
// `for_let_unit` lint should not be triggered by consuming them using for loop.
let v = vec![(), (), ()];
let mut count = 0;
for _ in v {
count += 1;
}
assert_eq!(count, 3);
// Same for consuming from some other Iterator<Item = ()>.
let (tx, rx) = ::std::sync::mpsc::channel();
tx.send(()).unwrap();
drop(tx);
count = 0;
for _ in rx.iter() {
count += 1;
}
assert_eq!(count, 1);
}
#[derive(Copy, Clone)]
pub struct ContainsUnit(()); // should be fine