rust/tests/ui/let_unit.rs

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// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
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#![warn(clippy::let_unit_value)]
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#![allow(unused_variables)]
macro_rules! let_and_return {
($n:expr) => {{
let ret = $n;
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}};
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}
fn main() {
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let _x = println!("x");
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let _y = 1; // this is fine
let _z = ((), 1); // this as well
if true {
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let _a = ();
}
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consume_units_with_for_loop(); // should be fine as well
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let_and_return!(()) // should be fine
}
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// 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);
}
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#[derive(Copy, Clone)]
pub struct ContainsUnit(()); // should be fine