Clippy lint · Style · checked with Clippy 0.1.99

clippy::infallible_destructuring_match: you seem to be trying to use `match` to destructure a single infallible pattern

What it meansChecks for matches being used to destructure a single-variant enum or tuple struct where a let will suffice. It is in the style group and warns by default.

What you see

warning: you seem to be trying to use `match` to destructure a single infallible pattern
  --> main.rs:9:1
   |
 9 | / let data = match wrapper {
10 | |     Wrapper::Data(i) => i,
11 | | };
   | |__^ help: consider using `let`: `let Wrapper::Data(data) = wrapper;`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#infallible_destructuring_match
   = note: `#[warn(clippy::infallible_destructuring_match)]` 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?

Just readability - let doesn’t nest, whereas a match does.

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

enum Wrapper {
    Data(i32),
}

let wrapper = Wrapper::Data(42);

let data = match wrapper {
    Wrapper::Data(i) => i,
};

Write this instead

enum Wrapper {
    Data(i32),
}

let wrapper = Wrapper::Data(42);
let Wrapper::Data(data) = wrapper;

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
infallible_destructuring_match = "allow"

One run

cargo clippy -- -A clippy::infallible-destructuring-match

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.

Stylegroup

warndefault level

yesfixed by cargo clippy --fix

pre 1.29.0added in Rust

Clippy's own documentation

What it does

Checks for matches being used to destructure a single-variant enum or tuple struct where a let will suffice.

Why is this bad?

Just readability - let doesn’t nest, whereas a match does.

Example

enum Wrapper {
    Data(i32),
}

let wrapper = Wrapper::Data(42);

let data = match wrapper {
    Wrapper::Data(i) => i,
};

The correct use would be:

enum Wrapper {
    Data(i32),
}

let wrapper = Wrapper::Data(42);
let Wrapper::Data(data) = wrapper;

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

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