e653ff03e9
As rustfmt checks fail, they might hide errors of more importance. Running it last makes sure that the serious bugs have been found and is less frustrating.
234 lines
8.6 KiB
Markdown
234 lines
8.6 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! 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
|
|
|
|
```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.
|
|
|
|
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 1.24.0 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 |
|
|
|
|
## 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
|