Clippy lint · Suspicious · checked with Clippy 0.1.99

clippy::needless_character_iteration: checking if a string is ascii using iterators

What it meansChecks if an iterator is used to check if a string is ascii. It is in the suspicious group and warns by default.

What you see

warning: checking if a string is ascii using iterators
 --> main.rs:3:1
  |
3 | "foo".chars().all(|c| c.is_ascii());
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `"foo".is_ascii()`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#needless_character_iteration
  = note: `#[warn(clippy::needless_character_iteration)]` 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 str type already implements the is_ascii method.

Code that is most likely wrong or useless. 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

"foo".chars().all(|c| c.is_ascii());

Write this instead

"foo".is_ascii();

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
needless_character_iteration = "allow"

One run

cargo clippy -- -A clippy::needless-character-iteration

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.

Suspiciousgroup

warndefault level

yesfixed by cargo clippy --fix

1.81.0added in Rust

Clippy's own documentation

What it does

Checks if an iterator is used to check if a string is ascii.

Why is this bad?

The str type already implements the is_ascii method.

Example

"foo".chars().all(|c| c.is_ascii());

Use instead:

"foo".is_ascii();

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

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