1# Rust
2
3Rust support is available natively in Zed.
4
5- Tree-sitter: [tree-sitter/tree-sitter-rust](https://github.com/tree-sitter/tree-sitter-rust)
6- Language Server: [rust-lang/rust-analyzer](https://github.com/rust-lang/rust-analyzer)
7
8<!--
9TBD: Polish Rust Docs. Zed is a good rust editor, good Rust docs make it look like we care about Rust (we do!)
10TBD: Users may not know what inlayHints, don't start there.
11TBD: Provide explicit examples not just `....`
12-->
13
14## Inlay Hints
15
16The following configuration can be used to change the inlay hint settings for `rust-analyzer` in Rust:
17
18```json
19{
20 "lsp": {
21 "rust-analyzer": {
22 "initialization_options": {
23 "inlayHints": {
24 "maxLength": null,
25 "lifetimeElisionHints": {
26 "enable": "skip_trivial",
27 "useParameterNames": true
28 },
29 "closureReturnTypeHints": {
30 "enable": "always"
31 }
32 }
33 }
34 }
35 }
36}
37```
38
39See [Inlay Hints](https://rust-analyzer.github.io/book/features.html#inlay-hints) in the Rust Analyzer Manual for more information.
40
41## Target directory
42
43The `rust-analyzer` target directory can be set in `initialization_options`:
44
45```json
46{
47 "lsp": {
48 "rust-analyzer": {
49 "initialization_options": {
50 "rust": {
51 "analyzerTargetDir": true
52 }
53 }
54 }
55 }
56}
57```
58
59A `true` setting will set the target directory to `target/rust-analyzer`. You can set a custom directory with a string like `"target/analyzer"` instead of `true`.
60
61## Binary
62
63You can configure which `rust-analyzer` binary Zed should use.
64
65By default, Zed will try to find a `rust-analyzer` in your `$PATH` and try to use that. If that binary successfully executes `rust-analyzer --help`, it's used. Otherwise, Zed will fall back to installing its own `rust-analyzer` version and using that.
66
67If you want to disable Zed looking for a `rust-analyzer` binary, you can set `ignore_system_version` to `true` in your `settings.json`:
68
69```json
70{
71 "lsp": {
72 "rust-analyzer": {
73 "binary": {
74 "ignore_system_version": true
75 }
76 }
77 }
78}
79```
80
81If you want to use a binary in a custom location, you can specify a `path` and optional `args`:
82
83```json
84{
85 "lsp": {
86 "rust-analyzer": {
87 "binary": {
88 "path": "/Users/example/bin/rust-analyzer",
89 "args": []
90 }
91 }
92 }
93}
94```
95
96This `"path"` has to be an absolute path.
97
98## Alternate Targets
99
100If want rust-analyzer to provide diagnostics for a target other than you current platform (e.g. for windows when running on macOS) you can use the following Zed lsp settings:
101
102```json
103{
104 "lsp": {
105 "rust-analyzer": {
106 "initialization_options": {
107 "cargo": {
108 "target": "x86_64-pc-windows-msvc"
109 }
110 }
111 }
112 }
113}
114```
115
116If you are using `rustup` and you can find a list of available target triples (`aarch64-apple-darwin`, `x86_64-unknown-linux-gnu`, etc) by running:
117
118```sh
119rustup target list --installed
120```
121
122## LSP tasks
123
124Zed provides tasks using tree-sitter, but rust-analyzer has an LSP extension method for querying file-related tasks via LSP.
125This is enabled by default and can be configured as
126
127```json
128"lsp": {
129 "rust-analyzer": {
130 "enable_lsp_tasks": true,
131 }
132}
133```
134
135## Manual Cargo Diagnostics fetch
136
137By default, rust-analyzer has `checkOnSave: true` enabled, which causes every buffer save to trigger a `cargo check --workspace --all-targets` command.
138For lager projects this might introduce excessive wait times, so a more fine-grained triggering could be enabled by altering the
139
140```json
141"diagnostics": {
142 "cargo": {
143 // When enabled, Zed disables rust-analyzer's check on save and starts to query
144 // Cargo diagnostics separately.
145 "fetch_cargo_diagnostics": false
146 }
147}
148```
149
150default settings.
151
152This will stop rust-analyzer from running `cargo check ...` on save, yet still allow to run
153`editor: run/clear/cancel flycheck` commands in Rust files to refresh cargo diagnostics; the project diagnostics editor will also refresh cargo diagnostics with `editor: run flycheck` command when the setting is enabled.
154
155## More server configuration
156
157<!--
158TBD: Is it possible to specify RUSTFLAGS? https://github.com/zed-industries/zed/issues/14334
159-->
160
161Rust-analyzer [manual](https://rust-analyzer.github.io/book/) describes various features and configuration options for rust-analyzer language server.
162Rust-analyzer in Zed runs with the default parameters.
163
164### Large projects and performance
165
166One of the main caveats that might cause extensive resource usage on large projects, is the combination of the following features:
167
168```
169rust-analyzer.checkOnSave (default: true)
170 Run the check command for diagnostics on save.
171```
172
173```
174rust-analyzer.check.workspace (default: true)
175 Whether --workspace should be passed to cargo check. If false, -p <package> will be passed instead.
176```
177
178```
179rust-analyzer.cargo.allTargets (default: true)
180 Pass --all-targets to cargo invocation
181```
182
183Which would mean that every time Zed saves, a `cargo check --workspace --all-targets` command is run, checking the entire project (workspace), lib, doc, test, bin, bench and [other targets](https://doc.rust-lang.org/cargo/reference/cargo-targets.html).
184
185While that works fine on small projects, it does not scale well.
186
187The alternatives would be to use [tasks](../tasks.md), as Zed already provides a `cargo check --workspace --all-targets` task and the ability to cmd/ctrl-click on the terminal output to navigate to the error, and limit or turn off the check on save feature entirely.
188
189Check on save feature is responsible for returning part of the diagnostics based on cargo check output, so turning it off will limit rust-analyzer with its own [diagnostics](https://rust-analyzer.github.io/book/diagnostics.html).
190
191Consider more `rust-analyzer.cargo.` and `rust-analyzer.check.` and `rust-analyzer.diagnostics.` settings from the manual for more fine-grained configuration.
192Here's a snippet for Zed settings.json (the language server will restart automatically after the `lsp.rust-analyzer` section is edited and saved):
193
194```json
195{
196 "lsp": {
197 "rust-analyzer": {
198 "initialization_options": {
199 // get more cargo-less diagnostics from rust-analyzer,
200 // which might include false-positives (those can be turned off by their names)
201 "diagnostics": {
202 "experimental": {
203 "enable": true
204 }
205 },
206 // To disable the checking entirely
207 // (ignores all cargo and check settings below)
208 "checkOnSave": false,
209 // To check the `lib` target only.
210 "cargo": {
211 "allTargets": false
212 },
213 // Use `-p` instead of `--workspace` for cargo check
214 "check": {
215 "workspace": false
216 }
217 }
218 }
219 }
220}
221```
222
223### Multi-project workspaces
224
225If you want rust-analyzer to analyze multiple Rust projects in the same folder that are not listed in `[members]` in the Cargo workspace,
226you can list them in `linkedProjects` in the local project settings:
227
228```json
229{
230 "lsp": {
231 "rust-analyzer": {
232 "initialization_options": {
233 "linkedProjects": ["./path/to/a/Cargo.toml", "./path/to/b/Cargo.toml"]
234 }
235 }
236 }
237}
238```
239
240### Snippets
241
242There's a way get custom completion items from rust-analyzer, that will transform the code according to the snippet body:
243
244```json
245{
246 "lsp": {
247 "rust-analyzer": {
248 "initialization_options": {
249 "completion": {
250 "snippets": {
251 "custom": {
252 "Arc::new": {
253 "postfix": "arc",
254 "body": ["Arc::new(${receiver})"],
255 "requires": "std::sync::Arc",
256 "scope": "expr"
257 },
258 "Some": {
259 "postfix": "some",
260 "body": ["Some(${receiver})"],
261 "scope": "expr"
262 },
263 "Ok": {
264 "postfix": "ok",
265 "body": ["Ok(${receiver})"],
266 "scope": "expr"
267 },
268 "Rc::new": {
269 "postfix": "rc",
270 "body": ["Rc::new(${receiver})"],
271 "requires": "std::rc::Rc",
272 "scope": "expr"
273 },
274 "Box::pin": {
275 "postfix": "boxpin",
276 "body": ["Box::pin(${receiver})"],
277 "requires": "std::boxed::Box",
278 "scope": "expr"
279 },
280 "vec!": {
281 "postfix": "vec",
282 "body": ["vec![${receiver}]"],
283 "description": "vec![]",
284 "scope": "expr"
285 }
286 }
287 }
288 }
289 }
290 }
291 }
292}
293```