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).
8 We are changing the default style used by rustfmt. There is an ongoing [RFC
9 process][fmt rfcs]. The last version using the old style was 0.8.6. From 0.9
10 onwards, the RFC style is the default. If you want the old style back, you can
11 use [legacy-rustfmt.toml](legacy-rustfmt.toml) as your 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18 to be a bit out of date).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.
21 You can use rustfmt in Travis CI builds. We provide a minimal Travis CI
22 configuration (see [here](#checking-style-on-a-ci-server)) and verify its status
23 using another repository. The status of that repository's build is reported by
24 the "travis example" badge above.
29 You can use `rustfmt` on Rust 1.24 and above.
34 rustup component add rustfmt-preview
37 to run on a cargo project in the current working directory:
46 rustup component add rustfmt-preview
49 ## Installing from source
51 To install from source, first checkout to the tag or branch you want to install, then issue
53 cargo install --path .
56 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
62 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
63 install`. This runs rustfmt on the given file, if the file includes out of line
64 modules, then we reformat those too. So to run on a whole module or crate, you
65 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
66 read data from stdin. Alternatively, you can use `cargo fmt` to format all
67 binary and library targets of your crate.
69 You'll probably want to specify the write mode. Currently, there are modes for
70 `diff`, `replace`, `overwrite`, `display`, `coverage`, `checkstyle`, and `plain`.
72 * `overwrite` Is the default and overwrites the original files _without_ creating backups.
73 * `replace` Overwrites the original files after creating backups of the files.
74 * `display` Will print the formatted files to stdout.
75 * `plain` Also writes to stdout, but with no metadata.
76 * `diff` Will print a diff between the original files and formatted files to stdout.
77 Will also exit with an error code if there are any differences.
78 * `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
79 that can be used by tools like Jenkins.
81 The write mode can be set by passing the `--write-mode` flag on
82 the command line. For example `rustfmt --write-mode=display src/filename.rs`
84 `cargo fmt` uses `--write-mode=overwrite` by default.
86 If you want to restrict reformatting to specific sets of lines, you can
87 use the `--file-lines` option. Its argument is a JSON array of objects
88 with `file` and `range` properties, where `file` is a file name, and
89 `range` is an array representing a range of lines like `[7,13]`. Ranges
90 are 1-based and inclusive of both end points. Specifying an empty array
91 will result in no files being formatted. For example,
94 rustfmt --file-lines '[
95 {"file":"src/lib.rs","range":[7,13]},
96 {"file":"src/lib.rs","range":[21,29]},
97 {"file":"src/foo.rs","range":[10,11]},
98 {"file":"src/foo.rs","range":[15,15]}]'
101 would format lines `7-13` and `21-29` of `src/lib.rs`, and lines `10-11`,
102 and `15` of `src/foo.rs`. No other files would be formatted, even if they
103 are included as out of line modules from `src/lib.rs`.
105 If `rustfmt` successfully reformatted the code it will exit with `0` exit
106 status. Exit status `1` signals some unexpected error, like an unknown option or
107 a failure to read a file. Exit status `2` is returned if there are syntax errors
108 in the input files. `rustfmt` can't format syntactically invalid code. Finally,
109 exit status `3` is returned if there are some issues which can't be resolved
110 automatically. For example, if you have a very long comment line `rustfmt`
111 doesn't split it. Instead it prints a warning and exits with `3`.
113 You can run `rustfmt --help` for more information.
116 ## Running Rustfmt from your editor
118 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
119 * [Emacs](https://github.com/rust-lang/rust-mode)
120 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
122 * 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.
124 ## Checking style on a CI server
126 To keep your code base consistently formatted, it can be helpful to fail the CI build
127 when a pull request contains unformatted code. Using `--write-mode=diff` instructs
128 rustfmt to exit with an error code if the input is not formatted correctly.
129 It will also print any found differences.
131 A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
136 - rustup component add rustfmt-preview
138 - cargo fmt --all -- --write-mode=diff
143 ## How to build and test
145 `cargo build` to build.
147 `cargo test` to run all tests.
149 To run Rustfmt, you'll need the binaries repo: https://github.com/rust-lang-nursery/rustfmt-bin
151 ## Configuring Rustfmt
153 Rustfmt is designed to be very configurable. You can create a TOML file called
154 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
155 directory and it will apply the options in that file. See `rustfmt
156 --config-help` for the options which are available, or if you prefer to see
157 visual style previews, [Configurations.md](Configurations.md).
159 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
160 guide] that has been formalized through the [style RFC
163 Configuration options are either stable or unstable. Stable options can always
164 be used, while unstable ones are only available on a nightly toolchain, and opt-in.
165 See [Configurations.md](Configurations.md) for details.
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
178 rustfmt. You can generate a file containing the default configuration with
179 `rustfmt --dump-default-config rustfmt.toml` and customize as needed.
180 * After successful compilation, a `rustfmt` executable can be found in the
182 * If you're having issues compiling Rustfmt (or compile errors when trying to
183 install), make sure you have the most recent version of Rust installed.
185 * If you get an error like `error while loading shared libraries` while starting
186 up rustfmt you should try the following:
191 export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
197 export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
200 On Windows (Git Bash/Mingw):
203 export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
206 (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
210 Rustfmt is distributed under the terms of both the MIT license and the
211 Apache License (Version 2.0).
213 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
215 [rust]: https://github.com/rust-lang/rust
216 [fmt rfcs]: https://github.com/rust-lang-nursery/fmt-rfcs
217 [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md