Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::diverging_sub_expression: Checks for diverging calls that are not match arms or statements

What it meansChecks for diverging calls that are not match arms or statements. It is in the complexity group and warns by default.

Does it matter?

It is often confusing to read. In addition, the sub-expression evaluation order for Rust is not well documented.

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

How to fix it

Clippy does not fix this one automatically. Change the code by hand:

Flagged

let a = b() || panic!() || c();
// `c()` is dead, `panic!()` is only called if `b()` returns `false`
let x = (a, b, c, panic!());
// can simply be replaced by `panic!()`

Turn it off, or on

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

On one item

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

Whole crate (Cargo.toml)

[lints.clippy]
diverging_sub_expression = "allow"

One run

cargo clippy -- -A clippy::diverging-sub-expression

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

pre 1.29.0added in Rust

Clippy's own documentation

What it does

Checks for diverging calls that are not match arms or statements.

Why is this bad?

It is often confusing to read. In addition, the sub-expression evaluation order for Rust is not well documented.

Known problems

Someone might want to use some_bool || panic!() as a shorthand.

Example

let a = b() || panic!() || c();
// `c()` is dead, `panic!()` is only called if `b()` returns `false`
let x = (a, b, c, panic!());
// can simply be replaced by `panic!()`

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

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