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Inspect CFG_RELEASE_CHANNEL env var at compile time |
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src | ||
tests | ||
.gitignore | ||
.travis.yml | ||
appveyor.yml | ||
atom.md | ||
bootstrap.sh | ||
build.rs | ||
Cargo.lock | ||
Cargo.toml | ||
CHANGELOG.md | ||
Configurations.md | ||
Contributing.md | ||
Design.md | ||
legacy-rustfmt.toml | ||
LICENSE-APACHE | ||
LICENSE-MIT | ||
README.md |
rustfmt
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.
We are changing the default style used by rustfmt. There is an ongoing RFC process. The last version using the old style was 0.8.6. From 0.9 onwards, the RFC style is the default. If you want the old style back, you can use legacy-rustfmt.toml as your rustfmt.toml.
The current master
branch uses libsyntax (part of the compiler). It is
published as rustfmt-nightly
. The syntex
branch uses Syntex instead of
libsyntax, it is published (for now) as rustfmt
. Most development happens on
the master
branch, however, this only supports nightly toolchains. If you use
stable or beta Rust toolchains, you must use the Syntex version (which is likely
to be a bit out of date). Version 0.1 of rustfmt-nightly is forked from version
0.9 of the syntex branch.
Quick start
You must be using the latest nightly compiler toolchain.
To install:
cargo install rustfmt-nightly
to run on a cargo project in the current working directory:
cargo fmt
Installation
cargo install rustfmt-nightly
or if you're using Rustup
rustup update
rustup run nightly cargo install rustfmt-nightly
If you don't have a nightly toolchain, you can add it using rustup:
rustup install nightly
You can make the nightly toolchain the default by running:
rustup default nightly
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
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'll probably want to specify the write mode. Currently, there are modes for
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.checkstyle
Will output the lines that need to be corrected as a checkstyle XML file, that can be used by tools like Jenkins.
The write mode can be set by passing the --write-mode
flag on
the command line. For example rustfmt --write-mode=display src/filename.rs
cargo fmt
uses --write-mode=overwrite
by default.
If you want to restrict reformatting to specific sets of lines, you can
use the --file-lines
option. Its argument is a JSON array of objects
with file
and range
properties, where file
is a file name, and
range
is an array representing a range of lines like [7,13]
. Ranges
are 1-based and inclusive of both end points. Specifying an empty array
will result in no files being formatted. For example,
rustfmt --file-lines '[
{"file":"src/lib.rs","range":[7,13]},
{"file":"src/lib.rs","range":[21,29]},
{"file":"src/foo.rs","range":[10,11]},
{"file":"src/foo.rs","range":[15,15]}]'
would format lines 7-13
and 21-29
of src/lib.rs
, and lines 10-11
,
and 15
of src/foo.rs
. No other files would be formatted, even if they
are included as out of line modules from src/lib.rs
.
If rustfmt
successfully reformatted the code it will exit with 0
exit
status. Exit status 1
signals some unexpected error, like an unknown option or
a failure to read a file. Exit status 2
is returned if there are syntax errors
in the input files. rustfmt
can't format syntactically invalid code. Finally,
exit status 3
is returned if there are some issues which can't be resolved
automatically. For example, if you have a very long comment line rustfmt
doesn't split it. Instead it prints a warning and exits with 3
.
You can run rustfmt --help
for more information.
Running Rustfmt from your editor
- Vim
- Emacs
- Sublime Text 3
- Atom
- Visual Studio Code using vscode-rust, vsc-rustfmt or rls_vscode through RLS.
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
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:
language: rust
cache: cargo
before_script:
- export PATH="$PATH:$HOME/.cargo/bin"
- which rustfmt || cargo install rustfmt
script:
- cargo fmt -- --write-mode=diff
- 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.
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 --config-help
for the options which are available, or if you prefer to see
visual style previews, Configurations.md.
By default, Rustfmt uses a style which conforms to the Rust style guide that has been formalized through the style RFC process.
Tips
-
For things you do not want rustfmt to mangle, use one of
#[rustfmt_skip] // requires nightly and #![feature(custom_attribute)] in crate root #[cfg_attr(rustfmt, rustfmt_skip)] // works in stable
-
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 withrustfmt --dump-default-config 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.
-
If you get an error like
error while loading shared libraries
while starting up rustfmt you should try the following:
On Linux:
export LD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$LD_LIBRARY_PATH
On MacOS:
export DYLD_LIBRARY_PATH=$(rustc --print sysroot)/lib:$DYLD_LIBRARY_PATH
On Windows (Git Bash/Mingw):
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).
License
Rustfmt is distributed under the terms of both the MIT license and the Apache License (Version 2.0).
See LICENSE-APACHE and LICENSE-MIT for details.