3.7 KiB
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.
Installation
Note: this method currently requires you to be running cargo 0.6.0 or newer.
cargo install --git https://github.com/rust-lang-nursery/rustfmt
or if you're using multirust
multirust run nightly cargo install --git https://github.com/rust-lang-nursery/rustfmt
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 --git https://github.com/rust-lang-nursery/rustfmt
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
replace, overwrite, display, and coverage. The replace mode is the default
and overwrites the original files after renaming them. In overwrite mode,
rustfmt does not backup the source files. To print the output to stdout, use the
display mode. The write mode can be set by passing the --write-mode
flag on
the command line.
rustfmt filename --write-mode=display
prints the output of rustfmt to the
screen, for example.
You can run rustfmt --help
for more information.
cargo fmt
uses --write-mode=overwrite
by default.
Running Rustfmt from your editor
How to build and test
First make sure you've got Rust 1.4.0 or greater available, then:
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.
What style does Rustfmt use?
Rustfmt is designed to be very configurable. You can create a TOML file called
rustfmt.toml, place it in the project directory and it will apply the options
in that file. See cargo run -- --config-help
for the options which are available,
or if you prefer to see source code, [src/config.rs].
By default, Rustfmt uses a style which (mostly) conforms to the Rust style guidelines. There are many details which the style guidelines do not cover, and in these cases we try to adhere to a style similar to that used in the Rust repo. Once Rustfmt is more complete, and able to re-format large repositories like Rust, we intend to go through the Rust RFC process to nail down the default style in detail.
If there are styling choices you don't agree with, we are usually happy to add options covering different styles. File an issue, or even better, submit a PR.
Gotchas
-
For things you do not want rustfmt to mangle, use one of
#[rustfmt_skip] #[cfg_attr(rustfmt, rustfmt_skip)]
-
When you run rustfmt, place a file named rustfmt.toml in target file directory or its parents to override the default settings of rustfmt.
-
After successful compilation, a
rustfmt
executable can be found in the target directory.