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).
+[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
## Quick start
-Currently, you can use `rustfmt` on nightly and beta. Rust 1.24 stable will work,
-but we're not quite there yet!
+You can use `rustfmt` on Rust 1.24 and above.
To install:
```
-rustup component add rustfmt-preview --toolchain=nightly
+rustup component add rustfmt-preview
```
-If `nightly` is your default toolchain, you can leave the `--toolchain` off.
-
to run on a cargo project in the current working directory:
```
-cargo +nightly fmt
+cargo fmt
```
-If `nightly` is your default toolchain, you can leave off the `+nightly`.
-
-## Installation
-
+For the latest and greatest `rustfmt` (nightly required):
```
-rustup component add rustfmt-preview --toolchain=nightly
+rustup component add rustfmt-preview --toolchain nightly
```
-
-If you don't have a nightly toolchain, you can add it using rustup:
-
+To run:
```
-rustup install nightly
+cargo +nightly fmt
```
-You can make the nightly toolchain the default by running:
+## 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 default nightly
+rustup component add rustfmt-preview
```
-If you choose not to do that you'll have to run rustfmt using `rustup run ...`
-or by adding `+nightly` to the cargo invocation.
-
## Installing from source
-To install from source, first checkout to the tag or branch you want to install, then issue
+To install from source (nightly required), first checkout to the tag or branch you want to install, then issue
```
-cargo install --path .
+cargo install --path .
```
This will install `rustfmt` in your `~/.cargo/bin`. Make sure to add `~/.cargo/bin` directory to
binary and library targets of your crate.
You'll probably want to specify the write mode. Currently, there are modes for
-`diff`, `replace`, `overwrite`, `display`, `coverage`, `checkstyle`, and `plain`.
+`check`, `diff`, `replace`, `overwrite`, `display`, `coverage`, `checkstyle`, and `plain`.
* `overwrite` Is the default and overwrites the original files _without_ creating backups.
* `replace` Overwrites the original files after creating backups of the files.
* `plain` Also writes to stdout, but with no metadata.
* `diff` Will print a diff between the original files and formatted files to stdout.
Will also exit with an error code if there are any differences.
+* `check` Checks if the program's formatting matches what rustfmt would do. Silently exits
+ with code 0 if so, emits a diff and exits with code 1 if not. This option is
+ designed to be run in CI-like where a non-zero exit signifies incorrect formatting.
* `checkstyle` Will output the lines that need to be corrected as a checkstyle XML file,
that can be used by tools like Jenkins.
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:
+A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
```yaml
language: rust
before_script:
-- rustup toolchain install nightly
-- rustup component add --toolchain nightly rustfmt-preview
-- which rustfmt || cargo install --force rustfmt-nightly
+- rustup component add rustfmt-preview
script:
-- cargo +nightly fmt --all -- --write-mode=diff
+- cargo fmt --all -- --write-mode=diff
- cargo build
- cargo test
```
projects / rust.git / blobdiff