Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::needless_bool_assign: Checks for expressions of the form if c { x = true } else { x = false } (or vice versa) and suggest assigning the variable directly from the condition

What it meansChecks for expressions of the form if c { x = true } else { x = false } (or vice versa) and suggest assigning the variable directly from the condition. It is in the complexity group and warns by default.

Does it matter?

Redundant code.

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

if must_keep(x, y) {
    skip = false;
} else {
    skip = true;
}

Write this instead

skip = !must_keep(x, y);

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
needless_bool_assign = "allow"

One run

cargo clippy -- -A clippy::needless-bool-assign

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

1.71.0added in Rust

Clippy's own documentation

What it does

Checks for expressions of the form if c { x = true } else { x = false } (or vice versa) and suggest assigning the variable directly from the condition.

Why is this bad?

Redundant code.

Example

if must_keep(x, y) {
    skip = false;
} else {
    skip = true;
}

Use instead:

skip = !must_keep(x, y);

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

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