Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::manual_ok_err: Checks for manual implementation of .ok() or .err() on Result values

What it meansChecks for manual implementation of .ok() or .err() on Result values. It is in the complexity group and warns by default.

Does it matter?

Using .ok() or .err() rather than a match or if let is less complex and more readable.

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 = match func() {
    Ok(v) => Some(v),
    Err(_) => None,
};
let b = if let Err(v) = func() {
    Some(v)
} else {
    None
};

Write this instead

let a = func().ok();
let b = func().err();

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_ok_err)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
manual_ok_err = "allow"

One run

cargo clippy -- -A clippy::manual-ok-err

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

1.86.0added in Rust

Clippy's own documentation

What it does

Checks for manual implementation of .ok() or .err() on Result values.

Why is this bad?

Using .ok() or .err() rather than a match or if let is less complex and more readable.

Example

let a = match func() {
    Ok(v) => Some(v),
    Err(_) => None,
};
let b = if let Err(v) = func() {
    Some(v)
} else {
    None
};

Use instead:

let a = func().ok();
let b = func().err();

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

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