191 lines
7.1 KiB
Markdown
191 lines
7.1 KiB
Markdown
# rustfmt [](https://travis-ci.org/rust-lang-nursery/rustfmt) [](https://ci.appveyor.com/api/projects/status/github/rust-lang-nursery/rustfmt)
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A tool for formatting Rust code according to style guidelines.
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If you'd like to help out (and you should, it's a fun project!), see
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[Contributing.md](Contributing.md).
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## Quick start
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To install:
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```
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cargo install rustfmt
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```
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to run on a cargo project in the current working directory:
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```
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cargo fmt
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```
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## Installation
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> **Note:** this method currently requires you to be running cargo 0.6.0 or
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> newer.
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```
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cargo install rustfmt
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```
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or if you're using [`rustup.rs`](https://www.rustup.rs/)
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```
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rustup run nightly cargo install rustfmt
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```
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Usually cargo-fmt, which enables usage of Cargo subcommand `cargo fmt`, is
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installed alongside rustfmt. To only install rustfmt run
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```
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cargo install --no-default-features rustfmt
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```
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## Installing from source
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To install from source, first checkout to the tag or branch you want to install, then issue
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```
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cargo install --path .
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```
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This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
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your PATH variable.
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## Running
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You can run Rustfmt by just typing `rustfmt filename` if you used `cargo
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install`. This runs rustfmt on the given file, if the file includes out of line
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modules, then we reformat those too. So to run on a whole module or crate, you
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just need to run on the root file (usually mod.rs or lib.rs). Rustfmt can also
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read data from stdin. Alternatively, you can use `cargo fmt` to format all
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binary and library targets of your crate.
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You'll probably want to specify the write mode. Currently, there are modes for
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diff, replace, overwrite, display, coverage, and checkstyle.
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* `replace` Is the default and overwrites the original files after creating backups of the files.
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* `overwrite` Overwrites the original files _without_ creating backups.
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* `display` Will print the formatted files to stdout.
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* `diff` Will print a diff between the original files and formatted files to stdout.
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Will also exit with an error code if there are any differences.
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* `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
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that can be used by tools like Jenkins.
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The write mode can be set by passing the `--write-mode` flag on
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the command line. For example `rustfmt --write-mode=display src/filename.rs`
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`cargo fmt` uses `--write-mode=replace` by default.
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If you want to restrict reformatting to specific sets of lines, you can
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use the `--file-lines` option. Its argument is a JSON array of objects
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with `file` and `range` properties, where `file` is a file name, and
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`range` is an array representing a range of lines like `[7,13]`. Ranges
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are 1-based and inclusive of both end points. Specifying an empty array
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will result in no files being formatted. For example,
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```
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rustfmt --file-lines '[
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{"file":"src/lib.rs","range":[7,13]},
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{"file":"src/lib.rs","range":[21,29]},
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{"file":"src/foo.rs","range":[10,11]},
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{"file":"src/foo.rs","range":[15,15]}]'
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```
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would format lines `7-13` and `21-29` of `src/lib.rs`, and lines `10-11`,
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and `15` of `src/foo.rs`. No other files would be formatted, even if they
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are included as out of line modules from `src/lib.rs`.
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If `rustfmt` successfully reformatted the code it will exit with `0` exit
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status. Exit status `1` signals some unexpected error, like an unknown option or
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a failure to read a file. Exit status `2` is returned if there are syntax errors
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in the input files. `rustfmt` can't format syntatically invalid code. Finally,
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exit status `3` is returned if there are some issues which can't be resolved
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automatically. For example, if you have a very long comment line `rustfmt`
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doesn't split it. Instead it prints a warning and exits with `3`.
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You can run `rustfmt --help` for more information.
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## Running Rustfmt from your editor
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* [Vim](https://github.com/rust-lang/rust.vim#formatting-with-rustfmt)
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* [Emacs](https://github.com/rust-lang/rust-mode)
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* [Sublime Text 3](https://packagecontrol.io/packages/BeautifyRust)
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* [Atom](atom.md)
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* 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.
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## Checking style on a CI server
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To keep your code base consistently formatted, it can be helpful to fail the CI build
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when a pull request contains unformatted code. Using `--write-mode=diff` instructs
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rustfmt to exit with an error code if the input is not formatted correctly.
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It will also print any found differences.
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A minimal Travis setup could look like this:
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```yaml
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language: rust
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cache: cargo
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before_script:
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- export PATH="$PATH:$HOME/.cargo/bin"
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- which rustfmt || cargo install rustfmt
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script:
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- cargo fmt -- --write-mode=diff
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- cargo build
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- cargo test
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```
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Note that using `cache: cargo` is optional but highly recommended to speed up the installation.
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## How to build and test
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`cargo build` to build.
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`cargo test` to run all tests.
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To run rustfmt after this, use `cargo run --bin rustfmt -- filename`. See the
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notes above on running rustfmt.
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## Configuring Rustfmt
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Rustfmt is designed to be very configurable. You can create a TOML file called
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`rustfmt.toml` or `.rustfmt.toml`, place it in the project or any other parent
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directory and it will apply the options in that file. See `rustfmt
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--config-help` for the options which are available, or if you prefer to see
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visual style previews, [Configurations.md](Configurations.md).
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By default, Rustfmt uses a style which (mostly) conforms to the
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[Rust style guidelines](https://doc.rust-lang.org/1.12.0/style/README.html).
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There are many details which the style guidelines do not cover, and in these
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cases we try to adhere to a style similar to that used in the
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[Rust repo](https://github.com/rust-lang/rust). Once Rustfmt is more complete, and
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able to re-format large repositories like Rust, we intend to go through the Rust
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RFC process to nail down the default style in detail.
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If there are styling choices you don't agree with, we are usually happy to add
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options covering different styles. File an issue, or even better, submit a PR.
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## Tips
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* For things you do not want rustfmt to mangle, use one of
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```rust
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#[rustfmt_skip] // requires nightly and #![feature(custom_attribute)] in crate root
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#[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
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```
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* When you run rustfmt, place a file named `rustfmt.toml` or `.rustfmt.toml` in
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target file directory or its parents to override the default settings of
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rustfmt.
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* After successful compilation, a `rustfmt` executable can be found in the
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target directory.
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* If you're having issues compiling Rustfmt (or compile errors when trying to
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install), make sure you have the most recent version of Rust installed.
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## License
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Rustfmt is distributed under the terms of both the MIT license and the
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Apache License (Version 2.0).
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See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) for details.
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