# 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) A tool for formatting Rust code according to style guidelines. If you'd like to help out (and you should, it's a fun project!), see [Contributing.md](Contributing.md) and our [Code of Conduct](CODE_OF_CONDUCT.md). We are changing the default style used by rustfmt. There is an ongoing [RFC process][fmt rfcs]. The last version using the old style was 0.8.6. From 0.9 onwards, the RFC style is the default. If you want the old style back, you can use [legacy-rustfmt.toml](legacy-rustfmt.toml) as your rustfmt.toml. The current `master` branch uses libsyntax (part of the compiler). It is published as `rustfmt-nightly`. The `syntex` branch uses Syntex instead of libsyntax, it is published (for now) as `rustfmt`. Most development happens on the `master` branch, however, this only supports nightly toolchains. If you use stable or beta Rust toolchains, you must use the Syntex version (which is likely to be a bit out of date). Version 0.1 of rustfmt-nightly is forked from version 0.9 of the syntex branch. You can use rustfmt in Travis CI builds. We provide a minimal Travis CI configuration (see [here](#checking-style-on-a-ci-server)) and verify its status using another repository. The status of that repository's build is reported by the "travis example" badge above. ## Quick start You can use `rustfmt` on Rust 1.24 and above. To install: ``` rustup component add rustfmt-preview ``` to run on a cargo project in the current working directory: ``` cargo fmt ``` For the latest and greatest `rustfmt` (nightly required): ``` rustup component add rustfmt-preview --toolchain nightly ``` To run: ``` cargo +nightly fmt ``` ## Limitations Rustfmt tries to work on as much Rust code as possible, sometimes, the code doesn't even need to compile! As we approach a 1.0 release we are also looking to limit areas of instability; in particular, post-1.0, the formatting of most code should not change as Rustfmt improves. However, there are some things that Rustfmt can't do or can't do well (and thus where formatting might change significantly, even post-1.0). We would like to reduce the list of limitations over time. The following list enumerates areas where Rustfmt does not work or where the stability guarantees do not apply (we don't make a distinction between the two because in the future Rustfmt might work on code where it currently does not): * a program where any part of the program does not parse (parsing is an early stage of compilation and in Rust includes macro expansion). * Macro declarations and uses (current status: some macro declarations and uses are formatted). * Comments, including any AST node with a comment 'inside' (Rustfmt does not currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future). * Rust code in code blocks in comments. * Any fragment of a program (i.e., stability guarantees only apply to whole programs, even where fragments of a program can be formatted today). * Code containing non-ascii unicode characters (we believe Rustfmt mostly works here, but do not have the test coverage or experience to be 100% sure). * Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug fixes to break our stability guarantees). ## Installation ``` rustup component add rustfmt-preview ``` ## Installing from source To install from source (nightly required), first checkout to the tag or branch you want to install, then issue ``` cargo install --path . ``` This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to your PATH variable. ## Running You can run Rustfmt by just typing `rustfmt filename` if you used `cargo install`. This runs rustfmt on the given file, if the file includes out of line modules, then we reformat those too. So to run on a whole module or crate, you just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also read data from stdin. Alternatively, you can use `cargo fmt` to format all binary and library targets of your crate. You can run `rustfmt --help` for information about argument. When running with `--check`, Rustfmt will exit with `0` if Rustfmt would not make any formatting changes to the input, and `1` if Rustfmt would make changes. In other modes, Rustfmt will exit with `1` if there was some error during formatting (for example a parsing or internal error) and `0` if formatting completed without error (whether or not changes were made). ## Running Rustfmt from your editor * [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt) * [Emacs](https://github.com/rust-lang/rust-mode) * [Sublime Text 3](https://packagecontrol.io/packages/RustFmt) * [Atom](atom.md) * 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. ## Checking style on a CI server To keep your code base consistently formatted, it can be helpful to fail the CI build when a pull request contains unformatted code. Using `--write-mode=check` instructs rustfmt to exit with an error code if the input is not formatted correctly. It will also print any found differences. A minimal Travis setup could look like this (requires Rust 1.24.0 or greater): ```yaml language: rust before_script: - rustup component add rustfmt-preview script: - cargo fmt --all -- --check - cargo build - cargo test ``` ## How to build and test `cargo build` to build. `cargo test` to run all tests. To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the notes above on running rustfmt. ## Configuring Rustfmt Rustfmt is designed to be very configurable. You can create a TOML file called `rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent directory and it will apply the options in that file. See `rustfmt --config-help` for the options which are available, or if you prefer to see visual style previews, [Configurations.md](Configurations.md). By default, Rustfmt uses a style which conforms to the [Rust style guide][style guide] that has been formalized through the [style RFC process][fmt rfcs]. Configuration options are either stable or unstable. Stable options can always be used, while unstable ones are only available on a nightly toolchain, and opt-in. See [Configurations.md](Configurations.md) for details. ## Tips * For things you do not want rustfmt to mangle, use one of ```rust #[rustfmt::skip] // requires nightly Rust and #![feature(tool_attributes)] in crate root #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable ``` * When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in target file directory or its parents to override the default settings of rustfmt. You can generate a file containing the default configuration with `rustfmt --dump-default-config rustfmt.toml` and customize as needed. * After successful compilation, a `rustfmt` executable can be found in the target directory. * If you're having issues compiling Rustfmt (or compile errors when trying to install), make sure you have the most recent version of Rust installed. * If you get an error like `error while loading shared libraries` while starting up rustfmt you should try the following: On Linux: ``` export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH ``` On MacOS: ``` export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH ``` On Windows (Git Bash/Mingw): ``` export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH ``` (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt). ## License Rustfmt is distributed under the terms of both the MIT license and the Apache License (Version 2.0). See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details. [rust]: https://github.com/rust-lang/rust [fmt rfcs]: https://github.com/rust-lang-nursery/fmt-rfcs [style guide]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md