1 # rustfmt [![Build Status](https://travis-ci.com/rust-lang/rustfmt.svg?branch=master)](https://travis-ci.com/rust-lang/rustfmt) [![Build Status](https://ci.appveyor.com/api/projects/status/github/rust-lang/rustfmt?svg=true)](https://ci.appveyor.com/project/rust-lang-libs/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.
18 ### On the Stable toolchain
23 rustup component add rustfmt
26 To run on a cargo project in the current working directory:
32 ### On the Nightly toolchain
34 For the latest and greatest `rustfmt`, nightly is required.
39 rustup component add rustfmt --toolchain nightly
42 To run on a cargo project in the current working directory:
50 Rustfmt tries to work on as much Rust code as possible. Sometimes, the code
51 doesn't even need to compile! As we approach a 1.0 release we are also looking
52 to limit areas of instability; in particular, post-1.0, the formatting of most
53 code should not change as Rustfmt improves. However, there are some things that
54 Rustfmt can't do or can't do well (and thus where formatting might change
55 significantly, even post-1.0). We would like to reduce the list of limitations
58 The following list enumerates areas where Rustfmt does not work or where the
59 stability guarantees do not apply (we don't make a distinction between the two
60 because in the future Rustfmt might work on code where it currently does not):
62 * a program where any part of the program does not parse (parsing is an early
63 stage of compilation and in Rust includes macro expansion).
64 * Macro declarations and uses (current status: some macro declarations and uses
66 * Comments, including any AST node with a comment 'inside' (Rustfmt does not
67 currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future).
68 * Rust code in code blocks in comments.
69 * Any fragment of a program (i.e., stability guarantees only apply to whole
70 programs, even where fragments of a program can be formatted today).
71 * Code containing non-ascii unicode characters (we believe Rustfmt mostly works
72 here, but do not have the test coverage or experience to be 100% sure).
73 * Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug
74 fixes to break our stability guarantees).
80 rustup component add rustfmt
83 ## Installing from source
85 To install from source (nightly required), first checkout to the tag or branch you want to install, then issue
88 cargo install --path .
91 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
97 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
98 install`. This runs rustfmt on the given file, if the file includes out of line
99 modules, then we reformat those too. So to run on a whole module or crate, you
100 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
101 read data from stdin. Alternatively, you can use `cargo fmt` to format all
102 binary and library targets of your crate.
104 You can run `rustfmt --help` for information about available arguments.
105 The easiest way to run rustfmt against a project is with `cargo fmt`. `cargo fmt` works on both
106 single-crate projects and [cargo workspaces](https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html).
107 Please see `cargo fmt --help` for usage information.
109 You can specify the path to your own `rustfmt` binary for cargo to use by setting the`RUSTFMT`
110 environment variable. This was added in v1.4.22, so you must have this version or newer to leverage this feature (`cargo fmt --version`)
112 ### Running `rustfmt` directly
114 To format individual files or arbitrary codes from stdin, the `rustfmt` binary should be used. Some
117 - `rustfmt lib.rs main.rs` will format "lib.rs" and "main.rs" in place
118 - `rustfmt` will read a code from stdin and write formatting to stdout
119 - `echo "fn main() {}" | rustfmt` would emit "fn main() {}".
121 For more information, including arguments and emit options, see `rustfmt --help`.
123 ### Verifying code is formatted
125 When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not
126 make any formatting changes to the input, and `1` if Rustfmt would make changes.
127 In other modes, Rustfmt will exit with `1` if there was some error during
128 formatting (for example a parsing or internal error) and `0` if formatting
129 completed without error (whether or not changes were made).
133 ## Running Rustfmt from your editor
135 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
136 * [Emacs](https://github.com/rust-lang/rust-mode)
137 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
139 * 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.
140 * [IntelliJ or CLion](intellij.md)
143 ## Checking style on a CI server
145 To keep your code base consistently formatted, it can be helpful to fail the CI build
146 when a pull request contains unformatted code. Using `--check` instructs
147 rustfmt to exit with an error code if the input is not formatted correctly.
148 It will also print any found differences. (Older versions of Rustfmt don't
149 support `--check`, use `--write-mode diff`).
151 A minimal Travis setup could look like this (requires Rust 1.31.0 or greater):
156 - rustup component add rustfmt
160 - cargo fmt --all -- --check
163 See [this blog post](https://medium.com/@ag_dubs/enforcing-style-in-ci-for-rust-projects-18f6b09ec69d)
166 ## How to build and test
168 `cargo build` to build.
170 `cargo test` to run all tests.
172 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
173 notes above on running rustfmt.
176 ## Configuring Rustfmt
178 Rustfmt is designed to be very configurable. You can create a TOML file called
179 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
180 directory and it will apply the options in that file. See `rustfmt
181 --help=config` for the options which are available, or if you prefer to see
182 visual style previews, [GitHub page](https://rust-lang.github.io/rustfmt/).
184 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
185 guide] that has been formalized through the [style RFC
188 Configuration options are either stable or unstable. Stable options can always
189 be used, while unstable ones are only available on a nightly toolchain, and opt-in.
190 See [GitHub page](https://rust-lang.github.io/rustfmt/) for details.
194 Rustfmt is able to pick up the edition used by reading the `Cargo.toml` file if
195 executed through the Cargo's formatting tool `cargo fmt`. Otherwise, the edition
196 needs to be specified in `rustfmt.toml`, e.g., with `edition = "2018"`.
200 * For things you do not want rustfmt to mangle, use `#[rustfmt::skip]`
201 * To prevent rustfmt from formatting a macro or an attribute,
202 use `#[rustfmt::skip::macros(target_macro_name)]` or
203 `#[rustfmt::skip::attributes(target_attribute_name)]`
208 #![rustfmt::skip::attributes(custom_attribute)]
210 #[custom_attribute(formatting , here , should , be , Skipped)]
211 #[rustfmt::skip::macros(html)]
213 let macro_result1 = html! { <div>
217 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
218 target file directory or its parents to override the default settings of
219 rustfmt. You can generate a file containing the default configuration with
220 `rustfmt --print-config default rustfmt.toml` and customize as needed.
221 * After successful compilation, a `rustfmt` executable can be found in the
223 * If you're having issues compiling Rustfmt (or compile errors when trying to
224 install), make sure you have the most recent version of Rust installed.
226 * You can change the way rustfmt emits the changes with the --emit flag:
231 cargo fmt -- --emit files
236 | Flag |Description| Nightly Only |
238 | files | overwrites output to files | No |
239 | stdout | writes output to stdout | No |
240 | coverage | displays how much of the input file was processed | Yes |
241 | checkstyle | emits in a checkstyle format | Yes |
242 | json | emits diffs in a json format | Yes |
246 Rustfmt is distributed under the terms of both the MIT license and the
247 Apache License (Version 2.0).
249 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
251 [rust]: https://github.com/rust-lang/rust
252 [fmt rfcs]: https://github.com/rust-dev-tools/fmt-rfcs
253 [style guide]: https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/guide.md