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) [![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
39 To format code that requires edition 2018, create a `rustfmt.toml` [configuration](#configuring-rustfmt) file containing:
42 edition = "Edition2018"
47 Rustfmt tries to work on as much Rust code as possible, sometimes, the code
48 doesn't even need to compile! As we approach a 1.0 release we are also looking
49 to limit areas of instability; in particular, post-1.0, the formatting of most
50 code should not change as Rustfmt improves. However, there are some things that
51 Rustfmt can't do or can't do well (and thus where formatting might change
52 significantly, even post-1.0). We would like to reduce the list of limitations
55 The following list enumerates areas where Rustfmt does not work or where the
56 stability guarantees do not apply (we don't make a distinction between the two
57 because in the future Rustfmt might work on code where it currently does not):
59 * a program where any part of the program does not parse (parsing is an early
60 stage of compilation and in Rust includes macro expansion).
61 * Macro declarations and uses (current status: some macro declarations and uses
63 * Comments, including any AST node with a comment 'inside' (Rustfmt does not
64 currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future).
65 * Rust code in code blocks in comments.
66 * Any fragment of a program (i.e., stability guarantees only apply to whole
67 programs, even where fragments of a program can be formatted today).
68 * Code containing non-ascii unicode characters (we believe Rustfmt mostly works
69 here, but do not have the test coverage or experience to be 100% sure).
70 * Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug
71 fixes to break our stability guarantees).
77 rustup component add rustfmt-preview
80 ## Installing from source
82 To install from source (nightly required), first checkout to the tag or branch you want to install, then issue
85 cargo install --path .
88 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
94 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
95 install`. This runs rustfmt on the given file, if the file includes out of line
96 modules, then we reformat those too. So to run on a whole module or crate, you
97 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
98 read data from stdin. Alternatively, you can use `cargo fmt` to format all
99 binary and library targets of your crate.
101 You can run `rustfmt --help` for information about argument.
103 When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not
104 make any formatting changes to the input, and `1` if Rustfmt would make changes.
105 In other modes, Rustfmt will exit with `1` if there was some error during
106 formatting (for example a parsing or internal error) and `0` if formatting
107 completed without error (whether or not changes were made).
111 ## Running Rustfmt from your editor
113 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
114 * [Emacs](https://github.com/rust-lang/rust-mode)
115 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
117 * 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.
120 ## Checking style on a CI server
122 To keep your code base consistently formatted, it can be helpful to fail the CI build
123 when a pull request contains unformatted code. Using `--check` instructs
124 rustfmt to exit with an error code if the input is not formatted correctly.
125 It will also print any found differences. (Older versions of Rustfmt don't
126 support `--check`, use `--write-mode diff`).
128 A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
135 - rustup component add rustfmt-preview
137 - cargo fmt --all -- --check
142 See [this blog post](https://medium.com/@ag_dubs/enforcing-style-in-ci-for-rust-projects-18f6b09ec69d)
145 ## How to build and test
147 `cargo build` to build.
149 `cargo test` to run all tests.
151 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
152 notes above on running rustfmt.
155 ## Configuring Rustfmt
157 Rustfmt is designed to be very configurable. You can create a TOML file called
158 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
159 directory and it will apply the options in that file. See `rustfmt
160 --help=config` for the options which are available, or if you prefer to see
161 visual style previews, [Configurations.md](Configurations.md).
163 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
164 guide] that has been formalized through the [style RFC
167 Configuration options are either stable or unstable. Stable options can always
168 be used, while unstable ones are only available on a nightly toolchain, and opt-in.
169 See [Configurations.md](Configurations.md) for details.
174 * For things you do not want rustfmt to mangle, use one of
177 #[rustfmt::skip] // requires nightly Rust and #![feature(tool_attributes)] in crate root
178 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
180 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
181 target file directory or its parents to override the default settings of
182 rustfmt. You can generate a file containing the default configuration with
183 `rustfmt --print-config default rustfmt.toml` and customize as needed.
184 * After successful compilation, a `rustfmt` executable can be found in the
186 * If you're having issues compiling Rustfmt (or compile errors when trying to
187 install), make sure you have the most recent version of Rust installed.
189 * If you get an error like `error while loading shared libraries` while starting
190 up rustfmt you should try the following:
195 export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
201 export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
204 On Windows (Git Bash/Mingw):
207 export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
210 (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
212 * You can change the way rustfmt emits the changes with the --emit flag:
217 cargo fmt --emit files
222 | Flag |Description| Nightly Only |
224 | files | overwrites output to files | No |
225 | stdout | writes output to stdout | No |
226 | coverage | displays how much of the input file was processed | Yes |
227 | checkstyle | emits in a checkstyle format | Yes |
231 Rustfmt is distributed under the terms of both the MIT license and the
232 Apache License (Version 2.0).
234 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
236 [rust]: https://github.com/rust-lang/rust
237 [fmt rfcs]: https://github.com/rust-lang-nursery/fmt-rfcs
238 [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md