1 # rustfmt [![Build Status](https://travis-ci.org/rust-lang-nursery/rustfmt.svg)](https://travis-ci.org/rust-lang-nursery/rustfmt) [![Build Status](https://ci.appveyor.com/api/projects/status/github/rust-lang-nursery/rustfmt?svg=true)](https://ci.appveyor.com/api/projects/status/github/rust-lang-nursery/rustfmt)
3 A tool for formatting Rust code according to style guidelines.
5 If you'd like to help out (and you should, it's a fun project!), see
6 [Contributing.md](Contributing.md).
16 to run on a cargo project in the current working directory:
24 > **Note:** this method currently requires you to be running cargo 0.6.0 or
31 or if you're using [`rustup.rs`](https://www.rustup.rs/)
34 rustup run nightly cargo install rustfmt
37 Usually cargo-fmt, which enables usage of Cargo subcommand `cargo fmt`, is
38 installed alongside rustfmt. To only install rustfmt run
41 cargo install --no-default-features rustfmt
43 ## Installing from source
45 To install from source, first checkout to the tag or branch you want to install, then issue
47 cargo install --path .
49 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
54 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
55 install`. This runs rustfmt on the given file, if the file includes out of line
56 modules, then we reformat those too. So to run on a whole module or crate, you
57 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
58 read data from stdin. Alternatively, you can use `cargo fmt` to format all
59 binary and library targets of your crate.
61 You'll probably want to specify the write mode. Currently, there are modes for
62 diff, replace, overwrite, display, coverage, and checkstyle.
64 * `replace` Is the default and overwrites the original files after creating backups of the files.
65 * `overwrite` Overwrites the original files _without_ creating backups.
66 * `display` Will print the formatted files to stdout.
67 * `diff` Will print a diff between the original files and formatted files to stdout.
68 Will also exit with an error code if there are any differences.
69 * `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
70 that can be used by tools like Jenkins.
72 The write mode can be set by passing the `--write-mode` flag on
73 the command line. For example `rustfmt --write-mode=display src/filename.rs`
75 `cargo fmt` uses `--write-mode=replace` by default.
77 If you want to restrict reformatting to specific sets of lines, you can
78 use the `--file-lines` option. Its argument is a JSON array of objects
79 with `file` and `range` properties, where `file` is a file name, and
80 `range` is an array representing a range of lines like `[7,13]`. Ranges
81 are 1-based and inclusive of both end points. Specifying an empty array
82 will result in no files being formatted. For example,
85 rustfmt --file-lines '[
86 {"file":"src/lib.rs","range":[7,13]},
87 {"file":"src/lib.rs","range":[21,29]},
88 {"file":"src/foo.rs","range":[10,11]},
89 {"file":"src/foo.rs","range":[15,15]}]'
92 would format lines `7-13` and `21-29` of `src/lib.rs`, and lines `10-11`,
93 and `15` of `src/foo.rs`. No other files would be formatted, even if they
94 are included as out of line modules from `src/lib.rs`.
96 If `rustfmt` successfully reformatted the code it will exit with `0` exit
97 status. Exit status `1` signals some unexpected error, like an unknown option or
98 a failure to read a file. Exit status `2` is returned if there are syntax errors
99 in the input files. `rustfmt` can't format syntatically invalid code. Finally,
100 exit status `3` is returned if there are some issues which can't be resolved
101 automatically. For example, if you have a very long comment line `rustfmt`
102 doesn't split it. Instead it prints a warning and exits with `3`.
104 You can run `rustfmt --help` for more information.
107 ## Running Rustfmt from your editor
109 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
110 * [Emacs](https://github.com/rust-lang/rust-mode)
111 * [Sublime Text 3](https://packagecontrol.io/packages/BeautifyRust)
113 * Visual Studio Code using [RustyCode](https://github.com/saviorisdead/RustyCode) or [vsc-rustfmt](https://github.com/Connorcpu/vsc-rustfmt)
115 ## Checking style on a CI server
117 To keep your code base consistently formatted, it can be helpful to fail the CI build
118 when a pull request contains unformatted code. Using `--write-mode=diff` instructs
119 rustfmt to exit with an error code if the input is not formatted correctly.
120 It will also print any found differences.
122 A minimal Travis setup could look like this:
128 - export PATH="$PATH:$HOME/.cargo/bin"
129 - which rustfmt || cargo install rustfmt
131 - cargo fmt -- --write-mode=diff
136 Note that using `cache: cargo` is optional but highly recommended to speed up the installation.
138 ## How to build and test
140 `cargo build` to build.
142 `cargo test` to run all tests.
144 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
145 notes above on running rustfmt.
148 ## Configuring Rustfmt
150 Rustfmt is designed to be very configurable. You can create a TOML file called
151 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
152 directory and it will apply the options in that file. See `rustfmt
153 --config-help` for the options which are available, or if you prefer to see
154 source code, [src/config.rs](src/config.rs).
156 By default, Rustfmt uses a style which (mostly) conforms to the
157 [Rust style guidelines](https://doc.rust-lang.org/1.12.0/style/README.html).
158 There are many details which the style guidelines do not cover, and in these
159 cases we try to adhere to a style similar to that used in the
160 [Rust repo](https://github.com/rust-lang/rust). Once Rustfmt is more complete, and
161 able to re-format large repositories like Rust, we intend to go through the Rust
162 RFC process to nail down the default style in detail.
164 If there are styling choices you don't agree with, we are usually happy to add
165 options covering different styles. File an issue, or even better, submit a PR.
170 * For things you do not want rustfmt to mangle, use one of
173 #[rustfmt_skip] // requires nightly and #![feature(custom_attribute)] in crate root
174 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
176 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
177 target file directory or its parents to override the default settings of
179 * After successful compilation, a `rustfmt` executable can be found in the
181 * If you're having issues compiling Rustfmt (or compile errors when trying to
182 install), make sure you have the most recent version of Rust installed.
187 Rustfmt is distributed under the terms of both the MIT license and the
188 Apache License (Version 2.0).
190 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.