1#[[ 2## Overview 3]]# 4 5[Rustfmt][rustfmt] is a tool for formatting Rust code according to style guidelines. 6By default, Rustfmt uses a style which conforms to the [Rust style guide][rsg] that 7has been formalized through the [style RFC process][rfcp]. A complete list of all 8configuration options can be found in the [Rustfmt GitHub Pages][rgp]. 9 10 11#[[ 12### Setup 13]]# 14 15Formatting your Rust targets' source code requires no setup outside of loading `rules_rust` 16in your workspace. Simply run `bazel run @rules_rust//:rustfmt` to format source code. 17 18In addition to this formatter, a simple check can be performed using the [rustfmt_aspect](#rustfmt-aspect) aspect by running 19```text 20bazel build --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect --output_groups=rustfmt_checks 21``` 22 23Add the following to a `.bazelrc` file to enable this check during the build phase. 24 25```text 26build --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect 27build --output_groups=+rustfmt_checks 28``` 29 30It's recommended to only enable this aspect in your CI environment so formatting issues do not 31impact user's ability to rapidly iterate on changes. 32 33The `rustfmt_aspect` also uses a `--@rules_rust//:rustfmt.toml` setting which determines the 34[configuration file][rgp] used by the formatter (`@rules_rust//tools/rustfmt`) and the aspect 35(`rustfmt_aspect`). This flag can be added to your `.bazelrc` file to ensure a consistent config 36file is used whenever `rustfmt` is run: 37 38```text 39build --@rules_rust//:rustfmt.toml=//:rustfmt.toml 40``` 41#[[ 42### Tips 43]]# 44 45Any target which uses Bazel generated sources will cause the `@rules_rust//tools/rustfmt` tool to fail with 46``failed to resolve mod `MOD` ``. To avoid failures, [`skip_children = true`](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=skip_chil#skip_children) 47is recommended to be set in the workspace's `rustfmt.toml` file which allows rustfmt to run on these targets 48without failing. 49 50[rustfmt]: https://github.com/rust-lang/rustfmt#readme 51[rsg]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md 52[rfcp]: https://github.com/rust-lang-nursery/fmt-rfcs 53[rgp]: https://rust-lang.github.io/rustfmt/ 54