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) [![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18 to be a bit out of date).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 You must be using the latest 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/)
48 rustup run nightly cargo install rustfmt-nightly
51 If you don't have a nightly toolchain, you can add it using rustup:
54 rustup install nightly
57 You can make the nightly toolchain the default by running:
60 rustup default nightly
63 If you choose not to do that you'll have to run rustfmt using `rustup run ...`
64 or by adding `+nightly` to the cargo invocation.
66 Usually cargo-fmt, which enables usage of Cargo subcommand `cargo fmt`, is
67 installed alongside rustfmt. To only install rustfmt run
70 cargo install --no-default-features rustfmt-nightly
72 ## Installing from source
74 To install from source, first checkout to the tag or branch you want to install, then issue
76 cargo install --path .
79 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
85 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
86 install`. This runs rustfmt on the given file, if the file includes out of line
87 modules, then we reformat those too. So to run on a whole module or crate, you
88 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
89 read data from stdin. Alternatively, you can use `cargo fmt` to format all
90 binary and library targets of your crate.
92 You'll probably want to specify the write mode. Currently, there are modes for
93 `diff`, `replace`, `overwrite`, `display`, `coverage`, `checkstyle`, and `plain`.
95 * `overwrite` Is the default and overwrites the original files _without_ creating backups.
96 * `replace` Overwrites the original files after creating backups of the files.
97 * `display` Will print the formatted files to stdout.
98 * `plain` Also writes to stdout, but with no metadata.
99 * `diff` Will print a diff between the original files and formatted files to stdout.
100 Will also exit with an error code if there are any differences.
101 * `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
102 that can be used by tools like Jenkins.
104 The write mode can be set by passing the `--write-mode` flag on
105 the command line. For example `rustfmt --write-mode=display src/filename.rs`
107 `cargo fmt` uses `--write-mode=overwrite` by default.
109 If you want to restrict reformatting to specific sets of lines, you can
110 use the `--file-lines` option. Its argument is a JSON array of objects
111 with `file` and `range` properties, where `file` is a file name, and
112 `range` is an array representing a range of lines like `[7,13]`. Ranges
113 are 1-based and inclusive of both end points. Specifying an empty array
114 will result in no files being formatted. For example,
117 rustfmt --file-lines '[
118 {"file":"src/lib.rs","range":[7,13]},
119 {"file":"src/lib.rs","range":[21,29]},
120 {"file":"src/foo.rs","range":[10,11]},
121 {"file":"src/foo.rs","range":[15,15]}]'
124 would format lines `7-13` and `21-29` of `src/lib.rs`, and lines `10-11`,
125 and `15` of `src/foo.rs`. No other files would be formatted, even if they
126 are included as out of line modules from `src/lib.rs`.
128 If `rustfmt` successfully reformatted the code it will exit with `0` exit
129 status. Exit status `1` signals some unexpected error, like an unknown option or
130 a failure to read a file. Exit status `2` is returned if there are syntax errors
131 in the input files. `rustfmt` can't format syntactically invalid code. Finally,
132 exit status `3` is returned if there are some issues which can't be resolved
133 automatically. For example, if you have a very long comment line `rustfmt`
134 doesn't split it. Instead it prints a warning and exits with `3`.
136 You can run `rustfmt --help` for more information.
139 ## Running Rustfmt from your editor
141 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
142 * [Emacs](https://github.com/rust-lang/rust-mode)
143 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
145 * 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.
147 ## Checking style on a CI server
149 To keep your code base consistently formatted, it can be helpful to fail the CI build
150 when a pull request contains unformatted code. Using `--write-mode=diff` instructs
151 rustfmt to exit with an error code if the input is not formatted correctly.
152 It will also print any found differences.
154 (These instructions use the Syntex version of Rustfmt. If you want to use the
155 nightly version replace `install rustfmt` with `install rustfmt-nightly`,
156 however you must then only run this with the nightly toolchain).
158 A minimal Travis setup could look like this:
164 - export PATH="$PATH:$HOME/.cargo/bin"
165 - which rustfmt || cargo install rustfmt
167 - cargo fmt -- --write-mode=diff
172 Note that using `cache: cargo` is optional but highly recommended to speed up the installation.
174 ## How to build and test
176 `cargo build` to build.
178 `cargo test` to run all tests.
180 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
181 notes above on running rustfmt.
184 ## Configuring Rustfmt
186 Rustfmt is designed to be very configurable. You can create a TOML file called
187 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
188 directory and it will apply the options in that file. See `rustfmt
189 --config-help` for the options which are available, or if you prefer to see
190 visual style previews, [Configurations.md](Configurations.md).
192 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
193 guide]. For details that have not yet been formalized through the [style RFC
194 process][fmt rfcs], we try to adhere to a style similar to that used in the
197 If there are styling choices you don't agree with, we are usually happy to add
198 options covering different styles. File an issue, or even better, submit a PR.
203 * For things you do not want rustfmt to mangle, use one of
206 #[rustfmt_skip] // requires nightly and #![feature(custom_attribute)] in crate root
207 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
209 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
210 target file directory or its parents to override the default settings of
211 rustfmt. You can generate a file containing the default configuration with
212 `rustfmt --dump-default-config rustfmt.toml` and customize as needed.
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.
218 * If you get an error like `error while loading shared libraries` while starting
219 up rustfmt you should try the following:
224 export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
230 export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
233 On Windows (Git Bash/Mingw):
236 export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
239 (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
243 Rustfmt is distributed under the terms of both the MIT license and the
244 Apache License (Version 2.0).
246 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
248 [rust]: https://github.com/rust-lang/rust
249 [fmt rfcs]: https://github.com/rust-lang-nursery/fmt-rfcs
250 [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md