Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::match_single_binding: Checks for useless match that binds to only one value

What it meansChecks for useless match that binds to only one value. It is in the complexity group and warns by default.

Does it matter?

Readability and needless complexity.

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

match (a, b) {
    (c, d) => {
        // useless match
    }
}

Write this instead

let (c, d) = (a, b);

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
match_single_binding = "allow"

One run

cargo clippy -- -A clippy::match-single-binding

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

1.43.0added in Rust

Clippy's own documentation

What it does

Checks for useless match that binds to only one value.

Why is this bad?

Readability and needless complexity.

Known problems

Suggested replacements may be incorrect when match is actually binding temporary value, bringing a ‘dropped while borrowed’ error.

Example

match (a, b) {
    (c, d) => {
        // useless match
    }
}

Use instead:

let (c, d) = (a, b);

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

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