xref: /aosp_15_r20/external/bazelbuild-rules_rust/docs/rust_analyzer.vm (revision d4726bddaa87cc4778e7472feed243fa4b6c267f) 
1#[[
2## Overview
3
4For [non-Cargo projects](https://rust-analyzer.github.io/manual.html#non-cargo-based-projects),
5[rust-analyzer](https://rust-analyzer.github.io/) depends on a `rust-project.json` file at the
6root of the project that describes its structure. The `rust_analyzer` rule facilitates generating
7such a file.
8
9### Setup
10
11First, ensure `rules_rust` is setup in your workspace. By default, `rust_register_toolchains` will
12ensure a [rust_analyzer_toolchain](#rust_analyzer_toolchain) is registered within the WORKSPACE.
13
14Next, load the dependencies for the `rust-project.json` generator tool:
15
16```python
17load("@rules_rust//tools/rust_analyzer:deps.bzl", "rust_analyzer_dependencies")
18
19rust_analyzer_dependencies()
20```
21
22Finally, run `bazel run @rules_rust//tools/rust_analyzer:gen_rust_project`
23whenever dependencies change to regenerate the `rust-project.json` file. It
24should be added to `.gitignore` because it is effectively a build artifact.
25Once the `rust-project.json` has been generated in the project root,
26rust-analyzer can pick it up upon restart.
27
28For users who do not use `rust_register_toolchains` to register toolchains, the following can be added
29to their WORKSPACE to register a `rust_analyzer_toolchain`. Please make sure the Rust version used in
30this toolchain matches the version used by the currently registered toolchain or the sources/documentation
31will not match what's being compiled with and can lead to confusing results.
32
33```python
34load("@rules_rust//rust:repositories.bzl", "rust_analyzer_toolchain_repository")
35
36register_toolchains(rust_analyzer_toolchain_repository(
37    name = "rust_analyzer_toolchain",
38    # This should match the currently registered toolchain.
39    version = "1.63.0",
40))
41```
42
43#### VSCode
44
45To set this up using [VSCode](https://code.visualstudio.com/), users should first install the
46[rust_analyzer plugin](https://marketplace.visualstudio.com/items?itemName=matklad.rust-analyzer).
47With that in place, the following task can be added to the `.vscode/tasks.json` file of the workspace
48to ensure a `rust-project.json` file is created and up to date when the editor is opened.
49
50```json
51{
52    "version": "2.0.0",
53    "tasks": [
54        {
55            "label": "Generate rust-project.json",
56            "command": "bazel",
57            "args": ["run", "@rules_rust//tools/rust_analyzer:gen_rust_project"],
58            "options": {
59                "cwd": "${workspaceFolder}"
60            },
61            "group": "build",
62            "problemMatcher": [],
63            "presentation": {
64                "reveal": "never",
65                "panel": "dedicated",
66            },
67            "runOptions": {
68                "runOn": "folderOpen"
69            }
70        },
71    ]
72}
73```
74
75#### Alternative vscode option (prototype)
76
77Add the following to your bazelrc:
78```
79build --@rules_rust//:output_diagnostics=true --output_groups=+rust_lib_rustc_output,+rust_metadata_rustc_output
80```
81
82Then 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.
83
84]]#
85