Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::manual_find: manual implementation of `Iterator::find`

What it meansChecks for manual implementations of Iterator::find It is in the complexity group and warns by default.

What you see

warning: manual implementation of `Iterator::find`
 --> main.rs:4:5
  |
4 | /     for el in arr {
5 | |         if el == 1 {
6 | |             return Some(el);
... |
9 | |     None
  | |________^ help: replace with an iterator: `arr.into_iter().find(|&el| el == 1)`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#manual_find
  = note: `#[warn(clippy::manual_find)]` 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?

It doesn’t affect performance, but using find is shorter and easier to read.

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

fn example(arr: Vec<i32>) -> Option<i32> {
    for el in arr {
        if el == 1 {
            return Some(el);
        }
    }
    None
}

Write this instead

fn example(arr: Vec<i32>) -> Option<i32> {
    arr.into_iter().find(|&el| el == 1)
}

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
manual_find = "allow"

One run

cargo clippy -- -A clippy::manual-find

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.

Complexitygroup

warndefault level

yesfixed by cargo clippy --fix

1.64.0added in Rust

Clippy's own documentation

What it does

Checks for manual implementations of Iterator::find

Why is this bad?

It doesn’t affect performance, but using find is shorter and easier to read.

Example

fn example(arr: Vec<i32>) -> Option<i32> {
    for el in arr {
        if el == 1 {
            return Some(el);
        }
    }
    None
}

Use instead:

fn example(arr: Vec<i32>) -> Option<i32> {
    arr.into_iter().find(|&el| el == 1)
}

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

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