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19 to be a bit out of date).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 use `rustfmt` on 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
55 Rustfmt tries to work on as much Rust code as possible, sometimes, the code
56 doesn't even need to compile! As we approach a 1.0 release we are also looking
57 to limit areas of instability; in particular, post-1.0, the formatting of most
58 code should not change as Rustfmt improves. However, there are some things that
59 Rustfmt can't do or can't do well (and thus where formatting might change
60 significantly, even post-1.0). We would like to reduce the list of limitations
63 The following list enumerates areas where Rustfmt does not work or where the
64 stability guarantees do not apply (we don't make a distinction between the two
65 because in the future Rustfmt might work on code where it currently does not):
67 * a program where any part of the program does not parse (parsing is an early
68 stage of compilation and in Rust includes macro expansion).
69 * Macro declarations and uses (current status: some macro declarations and uses
71 * Comments, including any AST node with a comment 'inside' (Rustfmt does not
72 currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future).
73 * Rust code in code blocks in comments.
74 * Any fragment of a program (i.e., stability guarantees only apply to whole
75 programs, even where fragments of a program can be formatted today).
76 * Code containing non-ascii unicode characters (we believe Rustfmt mostly works
77 here, but do not have the test coverage or experience to be 100% sure).
78 * Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug
79 fixes to break our stability guarantees).
85 rustup component add rustfmt-preview
88 ## Installing from source
90 To install from source (nightly required), first checkout to the tag or branch you want to install, then issue
92 cargo install --path .
95 This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
101 You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
102 install`. This runs rustfmt on the given file, if the file includes out of line
103 modules, then we reformat those too. So to run on a whole module or crate, you
104 just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
105 read data from stdin. Alternatively, you can use `cargo fmt` to format all
106 binary and library targets of your crate.
108 You can run `rustfmt --help` for information about argument.
110 When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not
111 make any formatting changes to the input, and `1` if Rustfmt would make changes.
112 In other modes, Rustfmt will exit with `1` if there was some error during
113 formatting (for example a parsing or internal error) and `0` if formatting
114 completed without error (whether or not changes were made).
118 ## Running Rustfmt from your editor
120 * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
121 * [Emacs](https://github.com/rust-lang/rust-mode)
122 * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt)
124 * 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.
127 ## Checking style on a CI server
129 To keep your code base consistently formatted, it can be helpful to fail the CI build
130 when a pull request contains unformatted code. Using `--check` instructs
131 rustfmt to exit with an error code if the input is not formatted correctly.
132 It will also print any found differences. (Older versions of Rustfmt don't
133 support `--check`, use `--write-mode diff`).
135 A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
142 - rustup component add rustfmt-preview
144 - cargo fmt --all -- --check
149 See [this blog post](https://medium.com/@ag_dubs/enforcing-style-in-ci-for-rust-projects-18f6b09ec69d)
152 ## How to build and test
154 `cargo build` to build.
156 `cargo test` to run all tests.
158 To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
159 notes above on running rustfmt.
162 ## Configuring Rustfmt
164 Rustfmt is designed to be very configurable. You can create a TOML file called
165 `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
166 directory and it will apply the options in that file. See `rustfmt
167 --config-help` for the options which are available, or if you prefer to see
168 visual style previews, [Configurations.md](Configurations.md).
170 By default, Rustfmt uses a style which conforms to the [Rust style guide][style
171 guide] that has been formalized through the [style RFC
174 Configuration options are either stable or unstable. Stable options can always
175 be used, while unstable ones are only available on a nightly toolchain, and opt-in.
176 See [Configurations.md](Configurations.md) for details.
181 * For things you do not want rustfmt to mangle, use one of
184 #[rustfmt::skip] // requires nightly Rust and #![feature(tool_attributes)] in crate root
185 #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
187 * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
188 target file directory or its parents to override the default settings of
189 rustfmt. You can generate a file containing the default configuration with
190 `rustfmt --dump-default-config rustfmt.toml` and customize as needed.
191 * After successful compilation, a `rustfmt` executable can be found in the
193 * If you're having issues compiling Rustfmt (or compile errors when trying to
194 install), make sure you have the most recent version of Rust installed.
196 * If you get an error like `error while loading shared libraries` while starting
197 up rustfmt you should try the following:
202 export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
208 export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
211 On Windows (Git Bash/Mingw):
214 export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
217 (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
221 Rustfmt is distributed under the terms of both the MIT license and the
222 Apache License (Version 2.0).
224 See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
226 [rust]: https://github.com/rust-lang/rust
227 [fmt rfcs]: https://github.com/rust-lang-nursery/fmt-rfcs
228 [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md