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)
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18 to be a bit out of date).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.
24 Currently, you can use `rustfmt` on nightly and beta. Rust 1.24 stable will work,
25 but we're not quite there yet!
30 rustup component add rustfmt-preview --toolchain=nightly
33 If `nightly` is your default toolchain, you can leave the `--toolchain` off.
35 to run on a cargo project in the current working directory:
41 If `nightly` is your default toolchain, you can leave off the `+nightly`.
46 rustup component add rustfmt-preview --toolchain=nightly
49 If you don't have a nightly toolchain, you can add it using rustup:
52 rustup install nightly
55 You can make the nightly toolchain the default by running:
58 rustup default nightly
61 If you choose not to do that you'll have to run rustfmt using `rustup run ...`
62 or by adding `+nightly` to the cargo invocation.
64 ## Installing from source
66 To install from source, first checkout to the tag or branch you want to install, then issue
68 cargo install --path .
71 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
77 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
78 install`. This runs rustfmt on the given file, if the file includes out of line
79 modules, then we reformat those too. So to run on a whole module or crate, you
80 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
81 read data from stdin. Alternatively, you can use `cargo fmt` to format all
82 binary and library targets of your crate.
84 You'll probably want to specify the write mode. Currently, there are modes for
85 `diff`, `replace`, `overwrite`, `display`, `coverage`, `checkstyle`, and `plain`.
87 * `overwrite` Is the default and overwrites the original files _without_ creating backups.
88 * `replace` Overwrites the original files after creating backups of the files.
89 * `display` Will print the formatted files to stdout.
90 * `plain` Also writes to stdout, but with no metadata.
91 * `diff` Will print a diff between the original files and formatted files to stdout.
92 Will also exit with an error code if there are any differences.
93 * `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
94 that can be used by tools like Jenkins.
96 The write mode can be set by passing the `--write-mode` flag on
97 the command line. For example `rustfmt --write-mode=display src/filename.rs`
99 `cargo fmt` uses `--write-mode=overwrite` by default.
101 If you want to restrict reformatting to specific sets of lines, you can
102 use the `--file-lines` option. Its argument is a JSON array of objects
103 with `file` and `range` properties, where `file` is a file name, and
104 `range` is an array representing a range of lines like `[7,13]`. Ranges
105 are 1-based and inclusive of both end points. Specifying an empty array
106 will result in no files being formatted. For example,
109 rustfmt --file-lines '[
110 {"file":"src/lib.rs","range":[7,13]},
111 {"file":"src/lib.rs","range":[21,29]},
112 {"file":"src/foo.rs","range":[10,11]},
113 {"file":"src/foo.rs","range":[15,15]}]'
116 would format lines `7-13` and `21-29` of `src/lib.rs`, and lines `10-11`,
117 and `15` of `src/foo.rs`. No other files would be formatted, even if they
118 are included as out of line modules from `src/lib.rs`.
120 If `rustfmt` successfully reformatted the code it will exit with `0` exit
121 status. Exit status `1` signals some unexpected error, like an unknown option or
122 a failure to read a file. Exit status `2` is returned if there are syntax errors
123 in the input files. `rustfmt` can't format syntactically invalid code. Finally,
124 exit status `3` is returned if there are some issues which can't be resolved
125 automatically. For example, if you have a very long comment line `rustfmt`
126 doesn't split it. Instead it prints a warning and exits with `3`.
128 You can run `rustfmt --help` for more information.
131 ## Running Rustfmt from your editor
133 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
134 * [Emacs](https://github.com/rust-lang/rust-mode)
135 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
137 * 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.
139 ## Checking style on a CI server
141 To keep your code base consistently formatted, it can be helpful to fail the CI build
142 when a pull request contains unformatted code. Using `--write-mode=diff` instructs
143 rustfmt to exit with an error code if the input is not formatted correctly.
144 It will also print any found differences.
146 (These instructions use the nightly version of Rustfmt. If you want to use the
147 Syntex version replace `install rustfmt-nightly` with `install rustfmt`).
149 A minimal Travis setup could look like this:
155 - export PATH="$PATH:$HOME/.cargo/bin"
156 - which rustfmt || cargo install rustfmt-nightly
158 - cargo fmt -- --write-mode=diff
163 Note that using `cache: cargo` is optional but highly recommended to speed up the installation.
165 ## How to build and test
167 `cargo build` to build.
169 `cargo test` to run all tests.
171 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
172 notes above on running rustfmt.
175 ## Configuring Rustfmt
177 Rustfmt is designed to be very configurable. You can create a TOML file called
178 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
179 directory and it will apply the options in that file. See `rustfmt
180 --config-help` for the options which are available, or if you prefer to see
181 visual style previews, [Configurations.md](Configurations.md).
183 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
184 guide] that has been formalized through the [style RFC
187 Configuration options are either stable or unstable. Stable options can always
188 be used, while unstable ones are only available on a nightly toolchain, and opt-in.
189 See [Configurations.md](Configurations.md) for details.
194 * For things you do not want rustfmt to mangle, use one of
197 #[rustfmt_skip] // requires nightly and #![feature(custom_attribute)] in crate root
198 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
200 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
201 target file directory or its parents to override the default settings of
202 rustfmt. You can generate a file containing the default configuration with
203 `rustfmt --dump-default-config rustfmt.toml` and customize as needed.
204 * After successful compilation, a `rustfmt` executable can be found in the
206 * If you're having issues compiling Rustfmt (or compile errors when trying to
207 install), make sure you have the most recent version of Rust installed.
209 * If you get an error like `error while loading shared libraries` while starting
210 up rustfmt you should try the following:
215 export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
221 export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
224 On Windows (Git Bash/Mingw):
227 export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
230 (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
234 Rustfmt is distributed under the terms of both the MIT license and the
235 Apache License (Version 2.0).
237 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
239 [rust]: https://github.com/rust-lang/rust
240 [fmt rfcs]: https://github.com/rust-lang-nursery/fmt-rfcs
241 [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md