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 We are changing the default style used by rustfmt. There is an ongoing [RFC
10 process][fmt rfcs]. The last version using the old style was 0.8.6. From 0.9
11 onwards, the RFC style is the default. If you want the old style back, you can
12 use [legacy-rustfmt.toml](legacy-rustfmt.toml) as your rustfmt.toml.
14 The current `master` branch uses libsyntax (part of the compiler). It is
15 published as `rustfmt-nightly`. The `syntex` branch uses Syntex instead of
16 libsyntax, it is published (for now) as `rustfmt`. Most development happens on
17 the `master` branch, however, this only supports nightly toolchains. If you use
18 stable or beta Rust toolchains, you must use the Syntex version (which is likely
19 to be a bit out of date). Version 0.1 of rustfmt-nightly is forked from version
20 0.9 of the syntex branch.
22 You can use rustfmt in Travis CI builds. We provide a minimal Travis CI
23 configuration (see [here](#checking-style-on-a-ci-server)) and verify its status
24 using another repository. The status of that repository's build is reported by
25 the "travis example" badge above.
30 You can run `rustfmt` with Rust 1.24 and above.
35 rustup component add rustfmt-preview
38 to run on a cargo project in the current working directory:
44 For the latest and greatest `rustfmt` (nightly required):
46 rustup component add rustfmt-preview --toolchain nightly
53 To format code that requires edition 2018, create a `rustfmt.toml` [configuration](#configuring-rustfmt) file containing:
56 edition = "Edition2018"
61 Rustfmt tries to work on as much Rust code as possible, sometimes, the code
62 doesn't even need to compile! As we approach a 1.0 release we are also looking
63 to limit areas of instability; in particular, post-1.0, the formatting of most
64 code should not change as Rustfmt improves. However, there are some things that
65 Rustfmt can't do or can't do well (and thus where formatting might change
66 significantly, even post-1.0). We would like to reduce the list of limitations
69 The following list enumerates areas where Rustfmt does not work or where the
70 stability guarantees do not apply (we don't make a distinction between the two
71 because in the future Rustfmt might work on code where it currently does not):
73 * a program where any part of the program does not parse (parsing is an early
74 stage of compilation and in Rust includes macro expansion).
75 * Macro declarations and uses (current status: some macro declarations and uses
77 * Comments, including any AST node with a comment 'inside' (Rustfmt does not
78 currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future).
79 * Rust code in code blocks in comments.
80 * Any fragment of a program (i.e., stability guarantees only apply to whole
81 programs, even where fragments of a program can be formatted today).
82 * Code containing non-ascii unicode characters (we believe Rustfmt mostly works
83 here, but do not have the test coverage or experience to be 100% sure).
84 * Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug
85 fixes to break our stability guarantees).
91 rustup component add rustfmt-preview
94 ## Installing from source
96 To install from source (nightly required), first checkout to the tag or branch you want to install, then issue
99 cargo install --path .
102 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
108 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
109 install`. This runs rustfmt on the given file, if the file includes out of line
110 modules, then we reformat those too. So to run on a whole module or crate, you
111 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
112 read data from stdin. Alternatively, you can use `cargo fmt` to format all
113 binary and library targets of your crate.
115 You can run `rustfmt --help` for information about argument.
117 When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not
118 make any formatting changes to the input, and `1` if Rustfmt would make changes.
119 In other modes, Rustfmt will exit with `1` if there was some error during
120 formatting (for example a parsing or internal error) and `0` if formatting
121 completed without error (whether or not changes were made).
125 ## Running Rustfmt from your editor
127 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
128 * [Emacs](https://github.com/rust-lang/rust-mode)
129 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
131 * 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.
134 ## Checking style on a CI server
136 To keep your code base consistently formatted, it can be helpful to fail the CI build
137 when a pull request contains unformatted code. Using `--check` instructs
138 rustfmt to exit with an error code if the input is not formatted correctly.
139 It will also print any found differences. (Older versions of Rustfmt don't
140 support `--check`, use `--write-mode diff`).
142 A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
149 - rustup component add rustfmt-preview
151 - cargo fmt --all -- --check
156 See [this blog post](https://medium.com/@ag_dubs/enforcing-style-in-ci-for-rust-projects-18f6b09ec69d)
159 ## How to build and test
161 `cargo build` to build.
163 `cargo test` to run all tests.
165 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
166 notes above on running rustfmt.
169 ## Configuring Rustfmt
171 Rustfmt is designed to be very configurable. You can create a TOML file called
172 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
173 directory and it will apply the options in that file. See `rustfmt
174 --config-help` for the options which are available, or if you prefer to see
175 visual style previews, [Configurations.md](Configurations.md).
177 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
178 guide] that has been formalized through the [style RFC
181 Configuration options are either stable or unstable. Stable options can always
182 be used, while unstable ones are only available on a nightly toolchain, and opt-in.
183 See [Configurations.md](Configurations.md) for details.
188 * For things you do not want rustfmt to mangle, use one of
191 #[rustfmt::skip] // requires nightly Rust and #![feature(tool_attributes)] in crate root
192 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
194 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
195 target file directory or its parents to override the default settings of
196 rustfmt. You can generate a file containing the default configuration with
197 `rustfmt --print-config default rustfmt.toml` and customize as needed.
198 * After successful compilation, a `rustfmt` executable can be found in the
200 * If you're having issues compiling Rustfmt (or compile errors when trying to
201 install), make sure you have the most recent version of Rust installed.
203 * If you get an error like `error while loading shared libraries` while starting
204 up rustfmt you should try the following:
209 export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
215 export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
218 On Windows (Git Bash/Mingw):
221 export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
224 (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
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 |
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-lang-nursery/fmt-rfcs
252 [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md