17. Using¶
rustfmt formats Rust code or checks if Rust code is well-formatted.
Code is “well formatted” if it complies with the Configuration.
17.1. rustfmt <file>...¶
To format one or more files, just pass the paths to rusfmt. This will
format the files and all of their child modules.
17.2. rustfmt --check <file>...¶
If the --check option is used, rusfmt checks if the files are
well-formatted. It reports what it would format, but will not modify any files.
For example:
$ rustfmt --check src/main.rs
Diff in /krate/src/main.rs at line 1:
fn main() {
- println!(
- "Hello, world!"
- );
+ println!("Hello, world!");
}
17.3. Exit codes¶
When running with --check, rustfmt will exit with status code 0 if
rustfmt would not make any formatting changes to the input, and status code
1 if rustfmt would make changes. In other modes, rustfmt will exit
with 1 if there was some error during formatting (for example a parsing or
internal error) and 0 if formatting completed without error (whether or not
changes were made).
17.4. Configuration¶
By default rustfmt formats code according to the
Rust Style Guide. The formatting can be
customized with the various config options. They can be
set in a config file (rustfmt.toml or .rustfmt.toml) or passed via the
command-line (--config).
17.5. cargo fmt¶
Caution
Use of cargo fmt is not qualified, and thus can’t be used in a safety
critical environment: in that case, you must invoke rustfmt directly.
rustfmt can be used “through” cargo to improve the user experience.
cargo fmt will format all the files in a cargo project.
cargo fmt --check will check that all files in a cargo project are
well-formatted.