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).
8 If you want latest and greatest, you should use the [libsyntax](https://github.com/rust-lang-nursery/rustfmt/tree/libsyntax)
9 branch. It supports some newer Rust syntax which is missing from master and
10 fixes some bugs. However, it links against libsyntax from the Rust compiler, so
11 you must be using a nightly version of Rust to use it.
21 to run on a cargo project in the current working directory:
29 > **Note:** this method currently requires you to be running cargo 0.6.0 or
36 or if you're using [`rustup.rs`](https://www.rustup.rs/)
39 rustup run nightly cargo install rustfmt
42 Usually cargo-fmt, which enables usage of Cargo subcommand `cargo fmt`, is
43 installed alongside rustfmt. To only install rustfmt run
46 cargo install --no-default-features rustfmt
48 ## Installing from source
50 To install from source, first checkout to the tag or branch you want to install, then issue
52 cargo install --path .
54 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
59 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
60 install`. This runs rustfmt on the given file, if the file includes out of line
61 modules, then we reformat those too. So to run on a whole module or crate, you
62 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
63 read data from stdin. Alternatively, you can use `cargo fmt` to format all
64 binary and library targets of your crate.
66 You'll probably want to specify the write mode. Currently, there are modes for
67 diff, replace, overwrite, display, coverage, and checkstyle.
69 * `replace` Is the default and overwrites the original files after creating backups of the files.
70 * `overwrite` Overwrites the original files _without_ creating backups.
71 * `display` Will print the formatted files to stdout.
72 * `diff` Will print a diff between the original files and formatted files to stdout.
73 Will also exit with an error code if there are any differences.
74 * `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
75 that can be used by tools like Jenkins.
77 The write mode can be set by passing the `--write-mode` flag on
78 the command line. For example `rustfmt --write-mode=display src/filename.rs`
80 `cargo fmt` uses `--write-mode=replace` by default.
82 If you want to restrict reformatting to specific sets of lines, you can
83 use the `--file-lines` option. Its argument is a JSON array of objects
84 with `file` and `range` properties, where `file` is a file name, and
85 `range` is an array representing a range of lines like `[7,13]`. Ranges
86 are 1-based and inclusive of both end points. Specifying an empty array
87 will result in no files being formatted. For example,
90 rustfmt --file-lines '[
91 {"file":"src/lib.rs","range":[7,13]},
92 {"file":"src/lib.rs","range":[21,29]},
93 {"file":"src/foo.rs","range":[10,11]},
94 {"file":"src/foo.rs","range":[15,15]}]'
97 would format lines `7-13` and `21-29` of `src/lib.rs`, and lines `10-11`,
98 and `15` of `src/foo.rs`. No other files would be formatted, even if they
99 are included as out of line modules from `src/lib.rs`.
101 If `rustfmt` successfully reformatted the code it will exit with `0` exit
102 status. Exit status `1` signals some unexpected error, like an unknown option or
103 a failure to read a file. Exit status `2` is returned if there are syntax errors
104 in the input files. `rustfmt` can't format syntatically invalid code. Finally,
105 exit status `3` is returned if there are some issues which can't be resolved
106 automatically. For example, if you have a very long comment line `rustfmt`
107 doesn't split it. Instead it prints a warning and exits with `3`.
109 You can run `rustfmt --help` for more information.
112 ## Running Rustfmt from your editor
114 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
115 * [Emacs](https://github.com/rust-lang/rust-mode)
116 * [Sublime Text 3](https://packagecontrol.io/packages/BeautifyRust)
118 * Visual Studio Code using [vscode-rust](https://github.com/editor-rs/vscode-rust), [vsc-rustfmt](https://github.com/Connorcpu/vsc-rustfmt) or [rls_vscode](https://github.com/jonathandturner/rls_vscode) through RLS.
120 ## Checking style on a CI server
122 To keep your code base consistently formatted, it can be helpful to fail the CI build
123 when a pull request contains unformatted code. Using `--write-mode=diff` instructs
124 rustfmt to exit with an error code if the input is not formatted correctly.
125 It will also print any found differences.
127 A minimal Travis setup could look like this:
133 - export PATH="$PATH:$HOME/.cargo/bin"
134 - which rustfmt || cargo install rustfmt
136 - cargo fmt -- --write-mode=diff
141 Note that using `cache: cargo` is optional but highly recommended to speed up the installation.
143 ## How to build and test
145 `cargo build` to build.
147 `cargo test` to run all tests.
149 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
150 notes above on running rustfmt.
153 ## Configuring Rustfmt
155 Rustfmt is designed to be very configurable. You can create a TOML file called
156 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
157 directory and it will apply the options in that file. See `rustfmt
158 --config-help` for the options which are available, or if you prefer to see
159 visual style previews, [Configurations.md](Configurations.md).
161 By default, Rustfmt uses a style which (mostly) conforms to the
162 [Rust style guidelines](https://doc.rust-lang.org/1.12.0/style/README.html).
163 There are many details which the style guidelines do not cover, and in these
164 cases we try to adhere to a style similar to that used in the
165 [Rust repo](https://github.com/rust-lang/rust). Once Rustfmt is more complete, and
166 able to re-format large repositories like Rust, we intend to go through the Rust
167 RFC process to nail down the default style in detail.
169 If there are styling choices you don't agree with, we are usually happy to add
170 options covering different styles. File an issue, or even better, submit a PR.
175 * For things you do not want rustfmt to mangle, use one of
178 #[rustfmt_skip] // requires nightly and #![feature(custom_attribute)] in crate root
179 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
181 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
182 target file directory or its parents to override the default settings of
184 * After successful compilation, a `rustfmt` executable can be found in the
186 * If you're having issues compiling Rustfmt (or compile errors when trying to
187 install), make sure you have the most recent version of Rust installed.
192 Rustfmt is distributed under the terms of both the MIT license and the
193 Apache License (Version 2.0).
195 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.