Rust Analyzer


For non-Cargo projects, rust-analyzer depends on a rust-project.json file at the root of the project that describes its structure. The rust_analyzer rule facilitates generating such a file.


First, ensure rules_rust is setup in your workspace. By default, rust_register_toolchains will ensure a rust_analyzer_toolchain is registered within the WORKSPACE.

Next, load the dependencies for the rust-project.json generator tool:

load("@rules_rust//tools/rust_analyzer:deps.bzl", "rust_analyzer_dependencies")


Finally, run bazel run @rules_rust//tools/rust_analyzer:gen_rust_project whenever dependencies change to regenerate the rust-project.json file. It should be added to .gitignore because it is effectively a build artifact. Once the rust-project.json has been generated in the project root, rust-analyzer can pick it up upon restart.

For users who do not use rust_register_toolchains to register toolchains, the following can be added to their WORKSPACE to register a rust_analyzer_toolchain. Please make sure the Rust version used in this toolchain matches the version used by the currently registered toolchain or the sources/documentation will not match what’s being compiled with and can lead to confusing results.

load("@rules_rust//rust:repositories.bzl", "rust_analyzer_toolchain_repository")

    name = "rust_analyzer_toolchain",
    # This should match the currently registered toolchain.
    version = "1.63.0",


To set this up using VSCode, users should first install the rust_analyzer plugin. With that in place, the following task can be added to the .vscode/tasks.json file of the workspace to ensure a rust-project.json file is created and up to date when the editor is opened.

    "version": "2.0.0",
    "tasks": [
            "label": "Generate rust-project.json",
            "command": "bazel",
            "args": ["run", "@rules_rust//tools/rust_analyzer:gen_rust_project"],
            "options": {
                "cwd": "${workspaceFolder}"
            "group": "build",
            "problemMatcher": [],
            "presentation": {
                "reveal": "never",
                "panel": "dedicated",
            "runOptions": {
                "runOn": "folderOpen"

Alternative vscode option (prototype)

Add the following to your bazelrc:

build --@rules_rust//:output_diagnostics=true --output_groups=+rust_lib_rustc_output,+rust_metadata_rustc_output

Then you can use a prototype rust-analyzer plugin that automatically collects the outputs whenever you recompile.


rust_analyzer_toolchain(name, proc_macro_srv, rustc, rustc_srcs)

A toolchain for rust-analyzer.


Name Description Type Mandatory Default
name A unique name for this target. Name required  
proc_macro_srv The path to a rust_analyzer_proc_macro_srv binary. Label optional None
rustc The path to a rustc binary. Label required  
rustc_srcs The source code of rustc. Label required  



Annotates rust rules with RustAnalyzerInfo later used to build a rust-project.json


Name Type
deps String
proc_macro_deps String
crate String
actual String
proto String


Name Description Type Mandatory Default
name A unique name for this target. Name required