-# rustfmt [](https://travis-ci.org/rust-lang-nursery/rustfmt) [](https://ci.appveyor.com/project/nrc/rustfmt) [](https://crates.io/crates/rustfmt-nightly)
+# rustfmt [](https://travis-ci.org/rust-lang-nursery/rustfmt) [](https://ci.appveyor.com/project/nrc/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).
+[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
to be a bit out of date). Version 0.1 of rustfmt-nightly is forked from version
0.9 of the syntex branch.
+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 must be using the latest nightly compiler toolchain.
+You can use `rustfmt` on Rust 1.24 and above.
To install:
```
-cargo install rustfmt-nightly
+rustup component add rustfmt-preview
```
to run on a cargo project in the current working directory:
cargo fmt
```
-## Installation
-
+For the latest and greatest `rustfmt` (nightly required):
```
-cargo install rustfmt-nightly
+rustup component add rustfmt-preview --toolchain nightly
```
-
-or if you're using [Rustup](https://www.rustup.rs/)
-
+To run:
```
-rustup update
-rustup run nightly cargo install rustfmt-nightly
+cargo +nightly fmt
```
-If you don't have a nightly toolchain, you can add it using rustup:
+## 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).
-```
-rustup install nightly
-```
-You can make the nightly toolchain the default by running:
+## 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.
-
-Usually cargo-fmt, which enables usage of Cargo subcommand `cargo fmt`, is
-installed alongside rustfmt. To only install rustfmt run
-
-```
-cargo install --no-default-features rustfmt-nightly
-```
## 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.
* `display` Will print the formatted files to stdout.
* `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.
## 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 `--write-mode=diff` instructs
+when a pull request contains unformatted code. Using `--write-mode=check` instructs
rustfmt to exit with an error code if the input is not formatted correctly.
It will also print any found differences.
-(These instructions use the Syntex version of Rustfmt. If you want to use the
-nightly version replace `install rustfmt` with `install rustfmt-nightly`,
-however you must then only run this with the nightly toolchain).
-
-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
-cache: cargo
before_script:
-- export PATH="$PATH:$HOME/.cargo/bin"
-- which rustfmt || cargo install rustfmt-nightly
+- rustup component add rustfmt-preview
script:
-- cargo fmt -- --write-mode=diff
+- cargo fmt --all -- --write-mode=check
- cargo build
- cargo test
```
-Note that using `cache: cargo` is optional but highly recommended to speed up the installation.
-
## How to build and test
`cargo build` to build.
* If you get an error like `error while loading shared libraries` while starting
up rustfmt you should try the following:
-On Linux:
+ On Linux:
-```
-export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
-```
+ ```
+ export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
+ ```
-On MacOS:
+ On MacOS:
-```
-export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
-```
+ ```
+ export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
+ ```
-On Windows (Git Bash/Mingw):
+ On Windows (Git Bash/Mingw):
-```
-export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
-```
+ ```
+ export PATH=$(rustc --print sysroot)/lib/rustlib/x86_64-pc-windows-gnu/lib/:$PATH
+ ```
-(Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
+ (Substitute `x86_64` by `i686` and `gnu` by `msvc` depending on which version of rustc was used to install rustfmt).
## License
projects / rust.git / blobdiff