Clippy lint · Style · checked with Clippy 0.1.99

clippy::implicit_saturating_sub: Checks for implicit saturating subtraction

What it meansChecks for implicit saturating subtraction. It is in the style group and warns by default.

Does it matter?

Simplicity and readability. Instead we can easily use an builtin function.

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 mut i: u32 = end - start;

if i != 0 {
    i -= 1;
}

Write this instead

let mut i: u32 = end - start;

i = i.saturating_sub(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::implicit_saturating_sub)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
implicit_saturating_sub = "allow"

One run

cargo clippy -- -A clippy::implicit-saturating-sub

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

1.44.0added in Rust

Clippy's own documentation

What it does

Checks for implicit saturating subtraction.

Why is this bad?

Simplicity and readability. Instead we can easily use an builtin function.

Example

let mut i: u32 = end - start;

if i != 0 {
    i -= 1;
}

Use instead:

let mut i: u32 = end - start;

i = i.saturating_sub(1);

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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