1*d4726bddSHONG Yifan#[[ 2*d4726bddSHONG Yifan## Overview 3*d4726bddSHONG Yifan]]# 4*d4726bddSHONG Yifan 5*d4726bddSHONG Yifan[Rustfmt][rustfmt] is a tool for formatting Rust code according to style guidelines. 6*d4726bddSHONG YifanBy default, Rustfmt uses a style which conforms to the [Rust style guide][rsg] that 7*d4726bddSHONG Yifanhas been formalized through the [style RFC process][rfcp]. A complete list of all 8*d4726bddSHONG Yifanconfiguration options can be found in the [Rustfmt GitHub Pages][rgp]. 9*d4726bddSHONG Yifan 10*d4726bddSHONG Yifan 11*d4726bddSHONG Yifan#[[ 12*d4726bddSHONG Yifan### Setup 13*d4726bddSHONG Yifan]]# 14*d4726bddSHONG Yifan 15*d4726bddSHONG YifanFormatting your Rust targets' source code requires no setup outside of loading `rules_rust` 16*d4726bddSHONG Yifanin your workspace. Simply run `bazel run @rules_rust//:rustfmt` to format source code. 17*d4726bddSHONG Yifan 18*d4726bddSHONG YifanIn addition to this formatter, a simple check can be performed using the [rustfmt_aspect](#rustfmt-aspect) aspect by running 19*d4726bddSHONG Yifan```text 20*d4726bddSHONG Yifanbazel build --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect --output_groups=rustfmt_checks 21*d4726bddSHONG Yifan``` 22*d4726bddSHONG Yifan 23*d4726bddSHONG YifanAdd the following to a `.bazelrc` file to enable this check during the build phase. 24*d4726bddSHONG Yifan 25*d4726bddSHONG Yifan```text 26*d4726bddSHONG Yifanbuild --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect 27*d4726bddSHONG Yifanbuild --output_groups=+rustfmt_checks 28*d4726bddSHONG Yifan``` 29*d4726bddSHONG Yifan 30*d4726bddSHONG YifanIt's recommended to only enable this aspect in your CI environment so formatting issues do not 31*d4726bddSHONG Yifanimpact user's ability to rapidly iterate on changes. 32*d4726bddSHONG Yifan 33*d4726bddSHONG YifanThe `rustfmt_aspect` also uses a `--@rules_rust//:rustfmt.toml` setting which determines the 34*d4726bddSHONG Yifan[configuration file][rgp] used by the formatter (`@rules_rust//tools/rustfmt`) and the aspect 35*d4726bddSHONG Yifan(`rustfmt_aspect`). This flag can be added to your `.bazelrc` file to ensure a consistent config 36*d4726bddSHONG Yifanfile is used whenever `rustfmt` is run: 37*d4726bddSHONG Yifan 38*d4726bddSHONG Yifan```text 39*d4726bddSHONG Yifanbuild --@rules_rust//:rustfmt.toml=//:rustfmt.toml 40*d4726bddSHONG Yifan``` 41*d4726bddSHONG Yifan#[[ 42*d4726bddSHONG Yifan### Tips 43*d4726bddSHONG Yifan]]# 44*d4726bddSHONG Yifan 45*d4726bddSHONG YifanAny target which uses Bazel generated sources will cause the `@rules_rust//tools/rustfmt` tool to fail with 46*d4726bddSHONG Yifan``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) 47*d4726bddSHONG Yifanis recommended to be set in the workspace's `rustfmt.toml` file which allows rustfmt to run on these targets 48*d4726bddSHONG Yifanwithout failing. 49*d4726bddSHONG Yifan 50*d4726bddSHONG Yifan[rustfmt]: https://github.com/rust-lang/rustfmt#readme 51*d4726bddSHONG Yifan[rsg]: https://github.com/rust-lang-nursery/fmt-rfcs/blob/master/guide/guide.md 52*d4726bddSHONG Yifan[rfcp]: https://github.com/rust-lang-nursery/fmt-rfcs 53*d4726bddSHONG Yifan[rgp]: https://rust-lang.github.io/rustfmt/ 54