Found explicitly ignored unit value RS-W1129
Anti-pattern
Minor
6 months ago
—
a year old
This statement is ignoring a unit type,
let binding is redundant31 .unwrap();
32 let test: String = cmd("GET").arg("test").query_async(&mut conn).await.unwrap();
33 assert_eq!(test, "test");
34 let _: () = cmd("DEL").arg("test").query_async(&mut conn).await.unwrap();35
36 // set the pool as the global pool
37 crate::REDIS_POOLThis statement is ignoring a unit type,
let binding is redundant23
24 // test the pool by setting a key and getting it, then deleting it
25 let mut conn = pool.get().await.unwrap();
26 let _: () = cmd("SET")27 .arg("test")28 .arg("test")29 .query_async(&mut conn)30 .await31 .unwrap();32 let test: String = cmd("GET").arg("test").query_async(&mut conn).await.unwrap();
33 assert_eq!(test, "test");
34 let _: () = cmd("DEL").arg("test").query_async(&mut conn).await.unwrap();
Description
The () type, also called “unit”, has exactly one value (), and is used when there is no other meaningful value that could be returned. It is most commonly seen implicitly: functions without a -> implicitly have return type (), that is, these are equivalent:
fn foo() {}
// vs,
fn foo() -> () {}
Hence explicitly ignoring values of unit type is redundant.
Bad practice
fn foo() {}
fn main() {
let _ = (); // bad
let _ = foo(); // bad
}
Recommended
fn foo() {}
fn main() {
(); // fine
foo(); // fine
}