253 lines
9.5 KiB
Markdown
253 lines
9.5 KiB
Markdown
# rustfmt [](https://travis-ci.com/rust-lang/rustfmt) [](https://ci.appveyor.com/project/rust-lang-libs/rustfmt) [](https://crates.io/crates/rustfmt-nightly) [](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).
|
|
|
|
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 run `rustfmt` with Rust 1.24 and above.
|
|
|
|
### On the Stable toolchain
|
|
|
|
To install:
|
|
|
|
```sh
|
|
rustup component add rustfmt
|
|
```
|
|
|
|
To run on a cargo project in the current working directory:
|
|
|
|
```sh
|
|
cargo fmt
|
|
```
|
|
|
|
### On the Nightly toolchain
|
|
|
|
For the latest and greatest `rustfmt`, nightly is required.
|
|
|
|
To install:
|
|
|
|
```sh
|
|
rustup component add rustfmt --toolchain nightly
|
|
```
|
|
|
|
To run on a cargo project in the current working directory:
|
|
|
|
```sh
|
|
cargo +nightly fmt
|
|
```
|
|
|
|
## Limitations
|
|
|
|
Rustfmt tries to work on as much Rust code as possible. Sometimes, the code
|
|
doesn't even need to compile! In general, we are 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
|
|
|
|
```sh
|
|
rustup component add rustfmt
|
|
```
|
|
|
|
## Installing from source
|
|
|
|
To install from source (nightly required), first checkout to the tag or branch you want to install, then issue
|
|
|
|
```sh
|
|
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 available arguments.
|
|
The easiest way to run rustfmt against a project is with `cargo fmt`. `cargo fmt` works on both
|
|
single-crate projects and [cargo workspaces](https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html).
|
|
Please see `cargo fmt --help` for usage information.
|
|
|
|
You can specify the path to your own `rustfmt` binary for cargo to use by setting the`RUSTFMT`
|
|
environment variable. This was added in v1.4.22, so you must have this version or newer to leverage this feature (`cargo fmt --version`)
|
|
|
|
### Running `rustfmt` directly
|
|
|
|
To format individual files or arbitrary codes from stdin, the `rustfmt` binary should be used. Some
|
|
examples follow:
|
|
|
|
- `rustfmt lib.rs main.rs` will format "lib.rs" and "main.rs" in place
|
|
- `rustfmt` will read a code from stdin and write formatting to stdout
|
|
- `echo "fn main() {}" | rustfmt` would emit "fn main() {}".
|
|
|
|
For more information, including arguments and emit options, see `rustfmt --help`.
|
|
|
|
### Verifying code is formatted
|
|
|
|
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.
|
|
* [IntelliJ or CLion](intellij.md)
|
|
|
|
|
|
## 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 `--check` instructs
|
|
rustfmt to exit with an error code if the input is not formatted correctly.
|
|
It will also print any found differences. (Older versions of Rustfmt don't
|
|
support `--check`, use `--write-mode diff`).
|
|
|
|
A minimal Travis setup could look like this (requires Rust 1.31.0 or greater):
|
|
|
|
```yaml
|
|
language: rust
|
|
before_script:
|
|
- rustup component add rustfmt
|
|
script:
|
|
- cargo build
|
|
- cargo test
|
|
- cargo fmt --all -- --check
|
|
```
|
|
|
|
See [this blog post](https://medium.com/@ag_dubs/enforcing-style-in-ci-for-rust-projects-18f6b09ec69d)
|
|
for more info.
|
|
|
|
## 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
|
|
--help=config` for the options which are available, or if you prefer to see
|
|
visual style previews, [GitHub page](https://rust-lang.github.io/rustfmt/).
|
|
|
|
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 [GitHub page](https://rust-lang.github.io/rustfmt/) for details.
|
|
|
|
### Rust's Editions
|
|
|
|
Rustfmt is able to pick up the edition used by reading the `Cargo.toml` file if
|
|
executed through the Cargo's formatting tool `cargo fmt`. Otherwise, the edition
|
|
needs to be specified in `rustfmt.toml`, e.g., with `edition = "2018"`.
|
|
|
|
## Tips
|
|
|
|
* For things you do not want rustfmt to mangle, use `#[rustfmt::skip]`
|
|
* To prevent rustfmt from formatting a macro or an attribute,
|
|
use `#[rustfmt::skip::macros(target_macro_name)]` or
|
|
`#[rustfmt::skip::attributes(target_attribute_name)]`
|
|
|
|
Example:
|
|
|
|
```rust
|
|
#![rustfmt::skip::attributes(custom_attribute)]
|
|
|
|
#[custom_attribute(formatting , here , should , be , Skipped)]
|
|
#[rustfmt::skip::macros(html)]
|
|
fn main() {
|
|
let macro_result1 = html! { <div>
|
|
Hello</div>
|
|
}.to_string();
|
|
```
|
|
* 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 --print-config default 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.
|
|
|
|
* You can change the way rustfmt emits the changes with the --emit flag:
|
|
|
|
Example:
|
|
|
|
```sh
|
|
cargo fmt -- --emit files
|
|
```
|
|
|
|
Options:
|
|
|
|
| Flag |Description| Nightly Only |
|
|
|:---:|:---:|:---:|
|
|
| files | overwrites output to files | No |
|
|
| stdout | writes output to stdout | No |
|
|
| coverage | displays how much of the input file was processed | Yes |
|
|
| checkstyle | emits in a checkstyle format | Yes |
|
|
| json | emits diffs in a json format | Yes |
|
|
|
|
## 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-dev-tools/fmt-rfcs
|
|
[style guide]: https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/guide.md
|