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// run-rustfix
#![feature(lint_reasons)]
#![warn(clippy::let_unit_value)]
#![allow(unused, clippy::no_effect, clippy::needless_late_init, path_statements)]
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
multiline_sugg();
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);
}
fn multiline_sugg() {
let v: Vec<u8> = vec![2];
let _ = v
.into_iter()
.map(|i| i * 2)
.filter(|i| i % 2 == 0)
.map(|_| ())
.next()
.unwrap();
}
#[derive(Copy, Clone)]
pub struct ContainsUnit(()); // should be fine
fn _returns_generic() {
fn f<T>() -> T {
unimplemented!()
}
fn f2<T, U>(_: T) -> U {
unimplemented!()
}
fn f3<T>(x: T) -> T {
x
}
fn f5<T: Default>(x: bool) -> Option<T> {
x.then(|| T::default())
}
let _: () = f(); // Ok
let x: () = f(); // Lint.
let _: () = f2(0i32); // Ok
let x: () = f2(0i32); // Lint.
let _: () = f3(()); // Lint
let x: () = f3(()); // Lint
// Should lint:
// fn f4<T>(mut x: Vec<T>) -> T {
// x.pop().unwrap()
// }
// let _: () = f4(vec![()]);
// let x: () = f4(vec![()]);
// Ok
let _: () = {
let x = 5;
f2(x)
};
let _: () = if true { f() } else { f2(0) }; // Ok
let x: () = if true { f() } else { f2(0) }; // Lint
// Ok
let _: () = match Some(0) {
None => f2(1),
Some(0) => f(),
Some(1) => f2(3),
Some(_) => f2('x'),
};
// Lint
let _: () = match Some(0) {
None => f2(1),
Some(0) => f(),
Some(1) => f2(3),
Some(_) => (),
};
let _: () = f5(true).unwrap();
#[allow(clippy::let_unit_value)]
{
let x = f();
let y;
let z;
match 0 {
0 => {
y = f();
z = f();
},
1 => {
println!("test");
y = f();
z = f3(());
},
_ => panic!(),
}
let x1;
let x2;
if true {
x1 = f();
x2 = x1;
} else {
x2 = f();
x1 = x2;
}
let opt;
match f5(true) {
Some(x) => opt = x,
None => panic!(),
};
#[warn(clippy::let_unit_value)]
{
let _: () = x;
let _: () = y;
let _: () = z;
let _: () = x1;
let _: () = x2;
let _: () = opt;
}
}
let () = f();
}
fn attributes() {
fn f() {}
#[allow(clippy::let_unit_value)]
let _ = f();
#[expect(clippy::let_unit_value)]
let _ = f();
}
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