# Rust Analyzer
* [rust_analyzer_aspect](#rust_analyzer_aspect)
* [rust_analyzer_toolchain](#rust_analyzer_toolchain)
## Overview
For [non-Cargo projects](https://rust-analyzer.github.io/manual.html#non-cargo-based-projects),
[rust-analyzer](https://rust-analyzer.github.io/) 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.
### Setup
First, ensure `rules_rust` is setup in your workspace. By default, `rust_register_toolchains` will
ensure a [rust_analyzer_toolchain](#rust_analyzer_toolchain) is registered within the WORKSPACE.
Next, load the dependencies for the `rust-project.json` generator tool:
```python
load("@rules_rust//tools/rust_analyzer:deps.bzl", "rust_analyzer_dependencies")
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.
```python
load("@rules_rust//rust:repositories.bzl", "rust_analyzer_toolchain_repository")
register_toolchains(rust_analyzer_toolchain_repository(
name = "rust_analyzer_toolchain",
# This should match the currently registered toolchain.
version = "1.63.0",
))
```
#### VSCode
To set this up using [VSCode](https://code.visualstudio.com/), users should first install the
[rust_analyzer plugin](https://marketplace.visualstudio.com/items?itemName=matklad.rust-analyzer).
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.
```json
{
"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](https://marketplace.visualstudio.com/items?itemName=MattStark.bazel-rust-analyzer) that automatically collects the outputs whenever you recompile.
## rust_analyzer_toolchain
rust_analyzer_toolchain(name, proc_macro_srv, rustc, rustc_srcs)
A toolchain for [rust-analyzer](https://rust-analyzer.github.io/).
**ATTRIBUTES**
| 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 | |
## rust_analyzer_aspect
rust_analyzer_aspect(name)
Annotates rust rules with RustAnalyzerInfo later used to build a rust-project.json
**ASPECT ATTRIBUTES**
| Name | Type |
| :------------- | :------------- |
| deps| String |
| proc_macro_deps| String |
| crate| String |
| actual| String |
| proto| String |
**ATTRIBUTES**
| Name | Description | Type | Mandatory | Default |
| :------------- | :------------- | :------------- | :------------- | :------------- |
| name | A unique name for this target. | Name | required | |