Clippy lint · Performance · checked with Clippy 0.1.99

clippy::collapsible_str_replace: Checks for consecutive calls to str::replace (2 or more) that can be collapsed into a single call

What it meansChecks for consecutive calls to str::replace (2 or more) that can be collapsed into a single call. It is in the performance group and warns by default.

Does it matter?

Consecutive str::replace calls scan the string multiple times with repetitive code.

Code that could be written to run faster. 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 hello = "hesuo worpd"
    .replace('s', "l")
    .replace("u", "l")
    .replace('p', "l");

Write this instead

let hello = "hesuo worpd".replace(['s', 'u', 'p'], "l");

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
collapsible_str_replace = "allow"

One run

cargo clippy -- -A clippy::collapsible-str-replace

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

Performancegroup

warndefault level

yesfixed by cargo clippy --fix

1.65.0added in Rust

Clippy's own documentation

What it does

Checks for consecutive calls to str::replace (2 or more) that can be collapsed into a single call.

Why is this bad?

Consecutive str::replace calls scan the string multiple times with repetitive code.

Example

let hello = "hesuo worpd"
    .replace('s', "l")
    .replace("u", "l")
    .replace('p', "l");

Use instead:

let hello = "hesuo worpd".replace(['s', 'u', 'p'], "l");

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.

Up next

Also worth your time

Did this answer your question?