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 We are changing the default style used by rustfmt. There is an ongoing [RFC process](https://github.com/rust-lang-nursery/fmt-rfcs).
9 The last version using the old style was 0.8.6. From 0.9 onwards, the RFC style
10 is the default. If you want the old style back, you can use [legacy-rustfmt.toml](legacy-rustfmt.toml)
13 The current `master` branch uses libsyntax (part of the compiler). It is
14 published as `rustfmt-nightly`. The `syntex` branch uses Syntex instead of
15 libsyntax, it is published (for now) as `rustfmt`. Most development happens on
16 the `master` branch, however, this only supports nightly toolchains. If you use
17 stable or beta Rust toolchains, you must use the Syntex version (which is likely
18 to be a bit out of date). Version 0.1 of rustfmt-nightly is forked from version
19 0.9 of the syntex branch.
24 You must be using a nightly compiler toolchain.
29 cargo install rustfmt-nightly
32 to run on a cargo project in the current working directory:
41 cargo install rustfmt-nightly
44 or if you're using [Rustup](https://www.rustup.rs/)
47 rustup run nightly cargo install rustfmt-nightly
50 If you don't have a nightly toolchain, you can add it using rustup:
53 rustup install nightly
56 You can make the nightly toolchain the default by running:
59 rustup default nightly
62 If you choose not to do that you'll have to run rustfmt using `rustup run ...`
63 or by adding `+nightly` to the cargo invocation.
65 Usually cargo-fmt, which enables usage of Cargo subcommand `cargo fmt`, is
66 installed alongside rustfmt. To only install rustfmt run
69 cargo install --no-default-features rustfmt-nightly
71 ## Installing from source
73 To install from source, first checkout to the tag or branch you want to install, then issue
75 cargo install --path .
78 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
84 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
85 install`. This runs rustfmt on the given file, if the file includes out of line
86 modules, then we reformat those too. So to run on a whole module or crate, you
87 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
88 read data from stdin. Alternatively, you can use `cargo fmt` to format all
89 binary and library targets of your crate.
91 You'll probably want to specify the write mode. Currently, there are modes for
92 diff, replace, overwrite, display, coverage, and checkstyle.
94 * `replace` Is the default and overwrites the original files after creating backups of the files.
95 * `overwrite` Overwrites the original files _without_ creating backups.
96 * `display` Will print the formatted files to stdout.
97 * `diff` Will print a diff between the original files and formatted files to stdout.
98 Will also exit with an error code if there are any differences.
99 * `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
100 that can be used by tools like Jenkins.
102 The write mode can be set by passing the `--write-mode` flag on
103 the command line. For example `rustfmt --write-mode=display src/filename.rs`
105 `cargo fmt` uses `--write-mode=replace` by default.
107 If you want to restrict reformatting to specific sets of lines, you can
108 use the `--file-lines` option. Its argument is a JSON array of objects
109 with `file` and `range` properties, where `file` is a file name, and
110 `range` is an array representing a range of lines like `[7,13]`. Ranges
111 are 1-based and inclusive of both end points. Specifying an empty array
112 will result in no files being formatted. For example,
115 rustfmt --file-lines '[
116 {"file":"src/lib.rs","range":[7,13]},
117 {"file":"src/lib.rs","range":[21,29]},
118 {"file":"src/foo.rs","range":[10,11]},
119 {"file":"src/foo.rs","range":[15,15]}]'
122 would format lines `7-13` and `21-29` of `src/lib.rs`, and lines `10-11`,
123 and `15` of `src/foo.rs`. No other files would be formatted, even if they
124 are included as out of line modules from `src/lib.rs`.
126 If `rustfmt` successfully reformatted the code it will exit with `0` exit
127 status. Exit status `1` signals some unexpected error, like an unknown option or
128 a failure to read a file. Exit status `2` is returned if there are syntax errors
129 in the input files. `rustfmt` can't format syntatically invalid code. Finally,
130 exit status `3` is returned if there are some issues which can't be resolved
131 automatically. For example, if you have a very long comment line `rustfmt`
132 doesn't split it. Instead it prints a warning and exits with `3`.
134 You can run `rustfmt --help` for more information.
137 ## Running Rustfmt from your editor
139 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
140 * [Emacs](https://github.com/rust-lang/rust-mode)
141 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
143 * 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.
145 ## Checking style on a CI server
147 To keep your code base consistently formatted, it can be helpful to fail the CI build
148 when a pull request contains unformatted code. Using `--write-mode=diff` instructs
149 rustfmt to exit with an error code if the input is not formatted correctly.
150 It will also print any found differences.
152 (These instructions use the Syntex version of Rustfmt. If you want to use the
153 nightly version replace `install rustfmt` with `install rustfmt-nightly`,
154 however you must then only run this with the nightly toolchain).
156 A minimal Travis setup could look like this:
162 - export PATH="$PATH:$HOME/.cargo/bin"
163 - which rustfmt || cargo install rustfmt
165 - cargo fmt -- --write-mode=diff
170 Note that using `cache: cargo` is optional but highly recommended to speed up the installation.
172 ## How to build and test
174 `cargo build` to build.
176 `cargo test` to run all tests.
178 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
179 notes above on running rustfmt.
182 ## Configuring Rustfmt
184 Rustfmt is designed to be very configurable. You can create a TOML file called
185 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
186 directory and it will apply the options in that file. See `rustfmt
187 --config-help` for the options which are available, or if you prefer to see
188 visual style previews, [Configurations.md](Configurations.md).
190 By default, Rustfmt uses a style which (mostly) conforms to the
191 [Rust style guidelines](https://doc.rust-lang.org/1.12.0/style/README.html).
192 There are many details which the style guidelines do not cover, and in these
193 cases we try to adhere to a style similar to that used in the
194 [Rust repo](https://github.com/rust-lang/rust). Once Rustfmt is more complete, and
195 able to re-format large repositories like Rust, we intend to go through the Rust
196 RFC process to nail down the default style in detail.
198 If there are styling choices you don't agree with, we are usually happy to add
199 options covering different styles. File an issue, or even better, submit a PR.
204 * For things you do not want rustfmt to mangle, use one of
207 #[rustfmt_skip] // requires nightly and #![feature(custom_attribute)] in crate root
208 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
210 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
211 target file directory or its parents to override the default settings of
213 * After successful compilation, a `rustfmt` executable can be found in the
215 * If you're having issues compiling Rustfmt (or compile errors when trying to
216 install), make sure you have the most recent version of Rust installed.
221 Rustfmt is distributed under the terms of both the MIT license and the
222 Apache License (Version 2.0).
224 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.