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/project/nrc/rustfmt) [![crates.io](https://img.shields.io/crates/v/rustfmt-nightly.svg)](https://crates.io/crates/rustfmt-nightly) [![Travis Configuration Status](https://img.shields.io/travis/davidalber/rustfmt-travis.svg?label=travis%20example)](https://travis-ci.org/davidalber/rustfmt-travis)
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) and our [Code of
7 Conduct](CODE_OF_CONDUCT.md).
9 We are changing the default style used by rustfmt. There is an ongoing [RFC
10 process][fmt rfcs]. The last version using the old style was 0.8.6. From 0.9
11 onwards, the RFC style is the default. If you want the old style back, you can
12 use [legacy-rustfmt.toml](legacy-rustfmt.toml) as your rustfmt.toml.
14 The current `master` branch uses libsyntax (part of the compiler). It is
15 published as `rustfmt-nightly`. The `syntex` branch uses Syntex instead of
16 libsyntax, it is published (for now) as `rustfmt`. Most development happens on
17 the `master` branch, however, this only supports nightly toolchains. If you use
18 stable or beta Rust toolchains, you must use the Syntex version (which is likely
19 to be a bit out of date). Version 0.1 of rustfmt-nightly is forked from version
20 0.9 of the syntex branch.
22 You can use rustfmt in Travis CI builds. We provide a minimal Travis CI
23 configuration (see [here](#checking-style-on-a-ci-server)) and verify its status
24 using another repository. The status of that repository's build is reported by
25 the "travis example" badge above.
30 You can use `rustfmt` on Rust 1.24 and above.
35 rustup component add rustfmt-preview
38 to run on a cargo project in the current working directory:
47 rustup component add rustfmt-preview
50 ## Installing from source
52 To install from source, first checkout to the tag or branch you want to install, then issue
54 cargo install --path .
57 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
63 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
64 install`. This runs rustfmt on the given file, if the file includes out of line
65 modules, then we reformat those too. So to run on a whole module or crate, you
66 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
67 read data from stdin. Alternatively, you can use `cargo fmt` to format all
68 binary and library targets of your crate.
70 You'll probably want to specify the write mode. Currently, there are modes for
71 `diff`, `replace`, `overwrite`, `display`, `coverage`, `checkstyle`, and `plain`.
73 * `overwrite` Is the default and overwrites the original files _without_ creating backups.
74 * `replace` Overwrites the original files after creating backups of the files.
75 * `display` Will print the formatted files to stdout.
76 * `plain` Also writes to stdout, but with no metadata.
77 * `diff` Will print a diff between the original files and formatted files to stdout.
78 Will also exit with an error code if there are any differences.
79 * `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
80 that can be used by tools like Jenkins.
82 The write mode can be set by passing the `--write-mode` flag on
83 the command line. For example `rustfmt --write-mode=display src/filename.rs`
85 `cargo fmt` uses `--write-mode=overwrite` by default.
87 If you want to restrict reformatting to specific sets of lines, you can
88 use the `--file-lines` option. Its argument is a JSON array of objects
89 with `file` and `range` properties, where `file` is a file name, and
90 `range` is an array representing a range of lines like `[7,13]`. Ranges
91 are 1-based and inclusive of both end points. Specifying an empty array
92 will result in no files being formatted. For example,
95 rustfmt --file-lines '[
96 {"file":"src/lib.rs","range":[7,13]},
97 {"file":"src/lib.rs","range":[21,29]},
98 {"file":"src/foo.rs","range":[10,11]},
99 {"file":"src/foo.rs","range":[15,15]}]'
102 would format lines `7-13` and `21-29` of `src/lib.rs`, and lines `10-11`,
103 and `15` of `src/foo.rs`. No other files would be formatted, even if they
104 are included as out of line modules from `src/lib.rs`.
106 If `rustfmt` successfully reformatted the code it will exit with `0` exit
107 status. Exit status `1` signals some unexpected error, like an unknown option or
108 a failure to read a file. Exit status `2` is returned if there are syntax errors
109 in the input files. `rustfmt` can't format syntactically invalid code. Finally,
110 exit status `3` is returned if there are some issues which can't be resolved
111 automatically. For example, if you have a very long comment line `rustfmt`
112 doesn't split it. Instead it prints a warning and exits with `3`.
114 You can run `rustfmt --help` for more information.
117 ## Running Rustfmt from your editor
119 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
120 * [Emacs](https://github.com/rust-lang/rust-mode)
121 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
123 * 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.
125 ## Checking style on a CI server
127 To keep your code base consistently formatted, it can be helpful to fail the CI build
128 when a pull request contains unformatted code. Using `--write-mode=diff` instructs
129 rustfmt to exit with an error code if the input is not formatted correctly.
130 It will also print any found differences.
132 A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
137 - rustup component add rustfmt-preview
139 - cargo fmt --all -- --write-mode=diff
144 ## How to build and test
146 `cargo build` to build.
148 `cargo test` to run all tests.
150 To run Rustfmt, you'll need the binaries repo: https://github.com/rust-lang-nursery/rustfmt-bin
152 ## Configuring Rustfmt
154 Rustfmt is designed to be very configurable. You can create a TOML file called
155 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
156 directory and it will apply the options in that file. See `rustfmt
157 --config-help` for the options which are available, or if you prefer to see
158 visual style previews, [Configurations.md](Configurations.md).
160 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
161 guide] that has been formalized through the [style RFC
164 Configuration options are either stable or unstable. Stable options can always
165 be used, while unstable ones are only available on a nightly toolchain, and opt-in.
166 See [Configurations.md](Configurations.md) for details.
171 * For things you do not want rustfmt to mangle, use one of
174 #[rustfmt_skip] // requires nightly and #![feature(custom_attribute)] in crate root
175 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
177 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
178 target file directory or its parents to override the default settings of
179 rustfmt. You can generate a file containing the default configuration with
180 `rustfmt --dump-default-config rustfmt.toml` and customize as needed.
181 * After successful compilation, a `rustfmt` executable can be found in the
183 * If you're having issues compiling Rustfmt (or compile errors when trying to
184 install), make sure you have the most recent version of Rust installed.
186 * If you get an error like `error while loading shared libraries` while starting
187 up rustfmt you should try the following:
192 export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
198 export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
201 On Windows (Git Bash/Mingw):
204 export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
207 (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
211 Rustfmt is distributed under the terms of both the MIT license and the
212 Apache License (Version 2.0).
214 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
216 [rust]: https://github.com/rust-lang/rust
217 [fmt rfcs]: https://github.com/rust-lang-nursery/fmt-rfcs
218 [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md