Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::unnecessary_get_then_check: Checks the usage of .get().is_some() or .get().is_none() on std map types

What it meansChecks the usage of .get().is_some() or .get().is_none() on std map types. It is in the complexity group and warns by default.

Does it matter?

It can be done in one call with .contains()/.contains_key().

Code that does something simple in a complicated way. Warns by default.

How to fix it

Clippy does not fix this one automatically (its suggestion may change behaviour, so it only shows it). Change the code by hand:

Flagged

let s: HashSet<String> = HashSet::new();
if s.get("a").is_some() {
    // code
}

Write this instead

let s: HashSet<String> = HashSet::new();
if s.contains("a") {
    // code
}

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
unnecessary_get_then_check = "allow"

One run

cargo clippy -- -A clippy::unnecessary-get-then-check

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

nofixed by cargo clippy --fix

1.78.0added in Rust

Clippy's own documentation

What it does

Checks the usage of .get().is_some() or .get().is_none() on std map types.

Why is this bad?

It can be done in one call with .contains()/.contains_key().

Example

let s: HashSet<String> = HashSet::new();
if s.get("a").is_some() {
    // code
}

Use instead:

let s: HashSet<String> = HashSet::new();
if s.contains("a") {
    // code
}

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

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