clippy::needless_splitn: unnecessary use of `splitn`

What you see

warning: unnecessary use of `splitn`
 --> main.rs:4:9
  |
4 | let _ = str.splitn(3, '=').next().unwrap();
  |         ^^^^^^^^^^^^^^^^^^ help: try: `str.split('=')`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#needless_splitn
  = note: `#[warn(clippy::needless_splitn)]` on by default

Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.

Does it matter?

The function split is simpler and there is no performance difference in these cases, considering that both functions return a lazy iterator.

Code that does something simple in a complicated way. Warns by default.

How to fix it

Clippy can fix this one for you: run cargo clippy --fix (add --allow-dirty if you have uncommitted changes). Review the diff before you commit.

Flagged

let str = "key=value=add";
let _ = str.splitn(3, '=').next().unwrap();

Write this instead

let str = "key=value=add";
let _ = str.split('=').next().unwrap();

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

#[allow(clippy::needless_splitn)]
fn my_function() { /* ... */ }

[lints.clippy]
needless_splitn = "allow"

cargo clippy -- -A clippy::needless-splitn

The [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.