Rust Rules

• Postsubmit
• Postsubmit + Current Bazel Incompatible Flags

Overview

This repository provides rules for building Rust projects with Bazel.

Basics

• rust_library
• rust_binary
• rust_test
• rust_doc
• rust_doc_test

WebAssembly

To build a rust_binary for wasm32-unknown-unknown add the --platforms=//rust/platform:wasm flag.

bazel build @examples//hello_world_wasm --platforms=//rust/platform:wasm

rust_wasm_bindgen will automatically transition to the wasm platform and can be used when building wasm code for the host target.

Protobuf

• rust_proto_library
• rust_grpc_library

with an overview here.

Setup

To use the Rust rules, add the following to your WORKSPACE file to add the external repositories for the Rust toolchain:

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "io_bazel_rules_rust",
    sha256 = "b6da34e057a31b8a85e343c732de4af92a762f804fc36b0baa6c001423a70ebc",
    strip_prefix = "rules_rust-55f77017a7f5b08e525ebeab6e11d8896a4499d2",
    urls = [
        # Master branch as of 2019-10-07
        "https://github.com/bazelbuild/rules_rust/archive/55f77017a7f5b08e525ebeab6e11d8896a4499d2.tar.gz",
    ],
)

http_archive(
    name = "bazel_skylib",
    sha256 = "9a737999532daca978a158f94e77e9af6a6a169709c0cee274f0a4c3359519bd",
    strip_prefix = "bazel-skylib-1.0.0",
    url = "https://github.com/bazelbuild/bazel-skylib/archive/1.0.0.tar.gz",
)

load("@io_bazel_rules_rust//rust:repositories.bzl", "rust_repositories")
rust_repositories()

load("@io_bazel_rules_rust//:workspace.bzl", "bazel_version")
bazel_version(name = "bazel_version")

The rules are under active development, as such the lastest commit on the master branch should be used. master currently requires Bazel >= 0.26.0.

Specifying Rust version

To build with a particular version of the Rust compiler, pass that version to rust_repositories:

rust_repositories(version = "1.42.0")

As well as an exact version, version can be set to "nightly" or "beta". If set to these values, iso_date must also be set:

rust_repositories(version = "nightly", iso_date = "2020-04-19")

Similarly, rustfmt_version may also be configured:

rust_repositories(rustfmt_version = "1.4.8")

External Dependencies

Currently the most common approach to managing external dependencies is using cargo-raze to generate BUILD files for Cargo crates.

Roadmap

• Improve expressiveness of features and support for Cargo's feature groups.
• Add cargo_crate workspace rule for pulling crates from Cargo.