Clippy lint · Style · checked with Clippy 0.1.99

clippy::manual_repeat_n: this `repeat().take()` can be written more concisely

What it meansChecks for repeat().take() that can be replaced with repeat_n(). It is in the style group and warns by default.

What you see

warning: this `repeat().take()` can be written more concisely
 --> main.rs:3:9
  |
3 | let _ = std::iter::repeat(10).take(3);
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `repeat_n()` instead: `std::iter::repeat_n(10, 3)`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#manual_repeat_n
  = note: `#[warn(clippy::manual_repeat_n)]` 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?

Using repeat_n() is more concise and clearer. Also, repeat_n() is sometimes faster than repeat().take() when the type of the element is non-trivial to clone because the original value can be reused for the last .next() call rather than always cloning.

Code that works but is not idiomatic Rust. 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 _ = std::iter::repeat(10).take(3);

Write this instead

let _ = std::iter::repeat_n(10, 3);

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_repeat_n)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
manual_repeat_n = "allow"

One run

cargo clippy -- -A clippy::manual-repeat-n

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.

Settings in clippy.toml

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

Stylegroup

warndefault level

yesfixed by cargo clippy --fix

1.86.0added in Rust

Clippy's own documentation

What it does

Checks for repeat().take() that can be replaced with repeat_n().

Why is this bad?

Using repeat_n() is more concise and clearer. Also, repeat_n() is sometimes faster than repeat().take() when the type of the element is non-trivial to clone because the original value can be reused for the last .next() call rather than always cloning.

Example

let _ = std::iter::repeat(10).take(3);

Use instead:

let _ = std::iter::repeat_n(10, 3);

Configuration

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

(default: current version)

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

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