Clippy lint · Restriction · checked with Clippy 0.1.99

clippy::exit: Detects calls to the exit() function that are not in the main function

What it meansDetects calls to the exit() function that are not in the main function. Calls to exit() immediately terminate the program. It is in the restriction group and off by default.

Does it matter?

exit() immediately terminates the program with no information other than an exit code. This provides no means to troubleshoot a problem, and may be an unexpected side effect. Codebases may use this lint to require that all exits are performed either by panicking (which produces a message, a code location, and optionally a backtrace) or by calling exit() from main() (which is a single place to look).

Lints that forbid language features for specific codebases (no unwrap, no indexing...). Off by default; pick them one by one, never the whole group.

How to fix it

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

Flagged

fn main() {
    std::process::exit(0);
}

Write this instead

fn main() {
    other_function();
}

fn other_function() {
    std::process::exit(0);
}

Turn it off, or on

It is off by default. To use it, set it to warn or deny:

Whole crate (Cargo.toml)

[lints.clippy]
exit = "warn"

In code

#![warn(clippy::exit)]

One run

cargo clippy -- -W clippy::exit

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.

Restrictiongroup

allowdefault level

nofixed by cargo clippy --fix

1.41.0added in Rust

Clippy's own documentation

What it does

Detects calls to the exit() function that are not in the main function. Calls to exit() immediately terminate the program.

Why restrict this?

exit() immediately terminates the program with no information other than an exit code. This provides no means to troubleshoot a problem, and may be an unexpected side effect.

Codebases may use this lint to require that all exits are performed either by panicking (which produces a message, a code location, and optionally a backtrace) or by calling exit() from main() (which is a single place to look).

Good example

fn main() {
    std::process::exit(0);
}

Bad example

fn main() {
    other_function();
}

fn other_function() {
    std::process::exit(0);
}

Use instead:

// To provide a stacktrace and additional information
panic!("message");

// or a main method with a return
fn main() -> Result<(), i32> {
    Ok(())
}

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

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