1 # rustfmt [![Build Status](https://travis-ci.org/rust-lang/rustfmt.svg)](https://travis-ci.org/rust-lang/rustfmt) [![Build Status](https://ci.appveyor.com/api/projects/status/github/rust-lang/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 You can use rustfmt in Travis CI builds. We provide a minimal Travis CI
10 configuration (see [here](#checking-style-on-a-ci-server)) and verify its status
11 using another repository. The status of that repository's build is reported by
12 the "travis example" badge above.
16 You can run `rustfmt` with Rust 1.24 and above.
21 rustup component add rustfmt-preview
24 to run on a cargo project in the current working directory:
30 For the latest and greatest `rustfmt` (nightly required):
32 rustup component add rustfmt-preview --toolchain nightly
41 Rustfmt tries to work on as much Rust code as possible, sometimes, the code
42 doesn't even need to compile! As we approach a 1.0 release we are also looking
43 to limit areas of instability; in particular, post-1.0, the formatting of most
44 code should not change as Rustfmt improves. However, there are some things that
45 Rustfmt can't do or can't do well (and thus where formatting might change
46 significantly, even post-1.0). We would like to reduce the list of limitations
49 The following list enumerates areas where Rustfmt does not work or where the
50 stability guarantees do not apply (we don't make a distinction between the two
51 because in the future Rustfmt might work on code where it currently does not):
53 * a program where any part of the program does not parse (parsing is an early
54 stage of compilation and in Rust includes macro expansion).
55 * Macro declarations and uses (current status: some macro declarations and uses
57 * Comments, including any AST node with a comment 'inside' (Rustfmt does not
58 currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future).
59 * Rust code in code blocks in comments.
60 * Any fragment of a program (i.e., stability guarantees only apply to whole
61 programs, even where fragments of a program can be formatted today).
62 * Code containing non-ascii unicode characters (we believe Rustfmt mostly works
63 here, but do not have the test coverage or experience to be 100% sure).
64 * Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug
65 fixes to break our stability guarantees).
71 rustup component add rustfmt-preview
74 ## Installing from source
76 To install from source (nightly required), first checkout to the tag or branch you want to install, then issue
79 cargo install --path .
82 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
88 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
89 install`. This runs rustfmt on the given file, if the file includes out of line
90 modules, then we reformat those too. So to run on a whole module or crate, you
91 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
92 read data from stdin. Alternatively, you can use `cargo fmt` to format all
93 binary and library targets of your crate.
95 You can run `rustfmt --help` for information about available arguments.
97 When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not
98 make any formatting changes to the input, and `1` if Rustfmt would make changes.
99 In other modes, Rustfmt will exit with `1` if there was some error during
100 formatting (for example a parsing or internal error) and `0` if formatting
101 completed without error (whether or not changes were made).
105 ## Running Rustfmt from your editor
107 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
108 * [Emacs](https://github.com/rust-lang/rust-mode)
109 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
111 * 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.
112 * [IntelliJ or CLion](intellij.md)
115 ## Checking style on a CI server
117 To keep your code base consistently formatted, it can be helpful to fail the CI build
118 when a pull request contains unformatted code. Using `--check` instructs
119 rustfmt to exit with an error code if the input is not formatted correctly.
120 It will also print any found differences. (Older versions of Rustfmt don't
121 support `--check`, use `--write-mode diff`).
123 A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
128 - rustup component add rustfmt-preview
130 - cargo fmt --all -- --check
135 See [this blog post](https://medium.com/@ag_dubs/enforcing-style-in-ci-for-rust-projects-18f6b09ec69d)
138 ## How to build and test
140 `cargo build` to build.
142 `cargo test` to run all tests.
144 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
145 notes above on running rustfmt.
148 ## Configuring Rustfmt
150 Rustfmt is designed to be very configurable. You can create a TOML file called
151 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
152 directory and it will apply the options in that file. See `rustfmt
153 --help=config` for the options which are available, or if you prefer to see
154 visual style previews, [Configurations.md](Configurations.md).
156 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
157 guide] that has been formalized through the [style RFC
160 Configuration options are either stable or unstable. Stable options can always
161 be used, while unstable ones are only available on a nightly toolchain, and opt-in.
162 See [Configurations.md](Configurations.md) for details.
167 * For things you do not want rustfmt to mangle, use `#[rustfmt::skip]`
168 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
169 target file directory or its parents to override the default settings of
170 rustfmt. You can generate a file containing the default configuration with
171 `rustfmt --print-config default rustfmt.toml` and customize as needed.
172 * After successful compilation, a `rustfmt` executable can be found in the
174 * If you're having issues compiling Rustfmt (or compile errors when trying to
175 install), make sure you have the most recent version of Rust installed.
177 * You can change the way rustfmt emits the changes with the --emit flag:
182 cargo fmt -- --emit files
187 | Flag |Description| Nightly Only |
189 | files | overwrites output to files | No |
190 | stdout | writes output to stdout | No |
191 | coverage | displays how much of the input file was processed | Yes |
192 | checkstyle | emits in a checkstyle format | Yes |
196 Rustfmt is distributed under the terms of both the MIT license and the
197 Apache License (Version 2.0).
199 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
201 [rust]: https://github.com/rust-lang/rust
202 [fmt rfcs]: https://github.com/rust-lang-nursery/fmt-rfcs
203 [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md