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
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
```
## 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.