Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::manual_option_zip: manual implementation of `Option::zip`

What it meansChecks for usage of a.and_then(|a| b.map(|b| (a, b))) which can be more concisely expressed as a.zip(b). It is in the complexity group and warns by default.

What you see

warning: manual implementation of `Option::zip`
 --> main.rs:5:9
  |
5 | let _ = a.and_then(|x| b.map(|y| (x, y)));
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `a.zip(b)`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#manual_option_zip
  = note: `#[warn(clippy::manual_option_zip)]` 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?

Option::zip is more concise and directly expresses the intent of combining two Option values into a tuple.

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

let a: Option<i32> = Some(1);
let b: Option<i32> = Some(2);
let _ = a.and_then(|x| b.map(|y| (x, y)));

Write this instead

let a: Option<i32> = Some(1);
let b: Option<i32> = Some(2);
let _ = a.zip(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::manual_option_zip)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
manual_option_zip = "allow"

One run

cargo clippy -- -A clippy::manual-option-zip

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

1.96.0added in Rust

Clippy's own documentation

What it does

Checks for usage of a.and_then(|a| b.map(|b| (a, b))) which can be more concisely expressed as a.zip(b).

Why is this bad?

Option::zip is more concise and directly expresses the intent of combining two Option values into a tuple.

Example

let a: Option<i32> = Some(1);
let b: Option<i32> = Some(2);
let _ = a.and_then(|x| b.map(|y| (x, y)));

Use instead:

let a: Option<i32> = Some(1);
let b: Option<i32> = Some(2);
let _ = a.zip(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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