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! In general, we are looking to limit areas of
52 instability; in particular, post-1.0, the formatting of most code should not
53 change as Rustfmt improves. However, there are some things that Rustfmt can't
54 do or can't do well (and thus where formatting might change significantly,
55 even post-1.0). We would like to reduce the list of limitations over time.
57 The following list enumerates areas where Rustfmt does not work or where the
58 stability guarantees do not apply (we don't make a distinction between the two
59 because in the future Rustfmt might work on code where it currently does not):
61 * a program where any part of the program does not parse (parsing is an early
62 stage of compilation and in Rust includes macro expansion).
63 * Macro declarations and uses (current status: some macro declarations and uses
65 * Comments, including any AST node with a comment 'inside' (Rustfmt does not
66 currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future).
67 * Rust code in code blocks in comments.
68 * Any fragment of a program (i.e., stability guarantees only apply to whole
69 programs, even where fragments of a program can be formatted today).
70 * Code containing non-ascii unicode characters (we believe Rustfmt mostly works
71 here, but do not have the test coverage or experience to be 100% sure).
72 * Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug
73 fixes to break our stability guarantees).
79 rustup component add rustfmt
82 ## Installing from source
84 To install from source (nightly required), first checkout to the tag or branch you want to install, then issue
87 cargo install --path .
90 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
96 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
97 install`. This runs rustfmt on the given file, if the file includes out of line
98 modules, then we reformat those too. So to run on a whole module or crate, you
99 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
100 read data from stdin. Alternatively, you can use `cargo fmt` to format all
101 binary and library targets of your crate.
103 You can run `rustfmt --help` for information about available arguments.
104 The easiest way to run rustfmt against a project is with `cargo fmt`. `cargo fmt` works on both
105 single-crate projects and [cargo workspaces](https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html).
106 Please see `cargo fmt --help` for usage information.
108 You can specify the path to your own `rustfmt` binary for cargo to use by setting the`RUSTFMT`
109 environment variable. This was added in v1.4.22, so you must have this version or newer to leverage this feature (`cargo fmt --version`)
111 ### Running `rustfmt` directly
113 To format individual files or arbitrary codes from stdin, the `rustfmt` binary should be used. Some
116 - `rustfmt lib.rs main.rs` will format "lib.rs" and "main.rs" in place
117 - `rustfmt` will read a code from stdin and write formatting to stdout
118 - `echo "fn main() {}" | rustfmt` would emit "fn main() {}".
120 For more information, including arguments and emit options, see `rustfmt --help`.
122 ### Verifying code is formatted
124 When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not
125 make any formatting changes to the input, and `1` if Rustfmt would make changes.
126 In other modes, Rustfmt will exit with `1` if there was some error during
127 formatting (for example a parsing or internal error) and `0` if formatting
128 completed without error (whether or not changes were made).
132 ## Running Rustfmt from your editor
134 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
135 * [Emacs](https://github.com/rust-lang/rust-mode)
136 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
138 * 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 * [IntelliJ or CLion](intellij.md)
142 ## Checking style on a CI server
144 To keep your code base consistently formatted, it can be helpful to fail the CI build
145 when a pull request contains unformatted code. Using `--check` instructs
146 rustfmt to exit with an error code if the input is not formatted correctly.
147 It will also print any found differences. (Older versions of Rustfmt don't
148 support `--check`, use `--write-mode diff`).
150 A minimal Travis setup could look like this (requires Rust 1.31.0 or greater):
155 - rustup component add rustfmt
159 - cargo fmt --all -- --check
162 See [this blog post](https://medium.com/@ag_dubs/enforcing-style-in-ci-for-rust-projects-18f6b09ec69d)
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 --help=config` for the options which are available, or if you prefer to see
181 visual style previews, [GitHub page](https://rust-lang.github.io/rustfmt/).
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 [GitHub page](https://rust-lang.github.io/rustfmt/) for details.
193 Rustfmt is able to pick up the edition used by reading the `Cargo.toml` file if
194 executed through the Cargo's formatting tool `cargo fmt`. Otherwise, the edition
195 needs to be specified in `rustfmt.toml`, e.g., with `edition = "2018"`.
199 * For things you do not want rustfmt to mangle, use `#[rustfmt::skip]`
200 * To prevent rustfmt from formatting a macro or an attribute,
201 use `#[rustfmt::skip::macros(target_macro_name)]` or
202 `#[rustfmt::skip::attributes(target_attribute_name)]`
207 #![rustfmt::skip::attributes(custom_attribute)]
209 #[custom_attribute(formatting , here , should , be , Skipped)]
210 #[rustfmt::skip::macros(html)]
212 let macro_result1 = html! { <div>
216 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
217 target file directory or its parents to override the default settings of
218 rustfmt. You can generate a file containing the default configuration with
219 `rustfmt --print-config default rustfmt.toml` and customize as needed.
220 * After successful compilation, a `rustfmt` executable can be found in the
222 * If you're having issues compiling Rustfmt (or compile errors when trying to
223 install), make sure you have the most recent version of Rust installed.
225 * You can change the way rustfmt emits the changes with the --emit flag:
230 cargo fmt -- --emit files
235 | Flag |Description| Nightly Only |
237 | files | overwrites output to files | No |
238 | stdout | writes output to stdout | No |
239 | coverage | displays how much of the input file was processed | Yes |
240 | checkstyle | emits in a checkstyle format | Yes |
241 | json | emits diffs in a json format | Yes |
245 Rustfmt is distributed under the terms of both the MIT license and the
246 Apache License (Version 2.0).
248 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
250 [rust]: https://github.com/rust-lang/rust
251 [fmt rfcs]: https://github.com/rust-dev-tools/fmt-rfcs
252 [style guide]: https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/guide.md