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## More server configuration
99
100<!--
101TBD: Is it possible to specify RUSTFLAGS? https://github.com/zed-industries/zed/issues/14334
102-->
103
104Rust-analyzer [manual](https://rust-analyzer.github.io/book/) describes various features and configuration options for rust-analyzer language server.
105Rust-analyzer in Zed runs with the default parameters.
106
107### Large projects and performance
108
109One of the main caveats that might cause extensive resource usage on large projects, is the combination of the following features:
110
111```
112rust-analyzer.checkOnSave (default: true)
113 Run the check command for diagnostics on save.
114```
115
116```
117rust-analyzer.check.workspace (default: true)
118 Whether --workspace should be passed to cargo check. If false, -p <package> will be passed instead.
119```
120
121```
122rust-analyzer.cargo.allTargets (default: true)
123 Pass --all-targets to cargo invocation
124```
125
126Which 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).
127
128While that works fine on small projects, it does not scale well.
129
130The 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.
131
132Check 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).
133
134Consider more `rust-analyzer.cargo.` and `rust-analyzer.check.` and `rust-analyzer.diagnostics.` settings from the manual for more fine-grained configuration.
135Here's a snippet for Zed settings.json (the language server will restart automatically after the `lsp.rust-analyzer` section is edited and saved):
136
137```json
138{
139 "lsp": {
140 "rust-analyzer": {
141 "initialization_options": {
142 // get more cargo-less diagnostics from rust-analyzer,
143 // which might include false-positives (those can be turned off by their names)
144 "diagnostics": {
145 "experimental": {
146 "enable": true
147 }
148 },
149 // To disable the checking entirely
150 // (ignores all cargo and check settings below)
151 "checkOnSave": false,
152 // To check the `lib` target only.
153 "cargo": {
154 "allTargets": false
155 },
156 // Use `-p` instead of `--workspace` for cargo check
157 "check": {
158 "workspace": false
159 }
160 }
161 }
162 }
163}
164```
165
166### Multi-project workspaces
167
168If you want rust-analyzer to analyze multiple Rust projects in the same folder that are not listed in `[members]` in the Cargo workspace,
169you can list them in `linkedProjects` in the local project settings:
170
171```json
172{
173 "lsp": {
174 "rust-analyzer": {
175 "initialization_options": {
176 "linkedProjects": ["./path/to/a/Cargo.toml", "./path/to/b/Cargo.toml"]
177 }
178 }
179 }
180}
181```
182
183### Snippets
184
185There's a way get custom completion items from rust-analyzer, that will transform the code according to the snippet body:
186
187```json
188{
189 "lsp": {
190 "rust-analyzer": {
191 "initialization_options": {
192 "completion": {
193 "snippets": {
194 "custom": {
195 "Arc::new": {
196 "postfix": "arc",
197 "body": ["Arc::new(${receiver})"],
198 "requires": "std::sync::Arc",
199 "scope": "expr"
200 },
201 "Some": {
202 "postfix": "some",
203 "body": ["Some(${receiver})"],
204 "scope": "expr"
205 },
206 "Ok": {
207 "postfix": "ok",
208 "body": ["Ok(${receiver})"],
209 "scope": "expr"
210 },
211 "Rc::new": {
212 "postfix": "rc",
213 "body": ["Rc::new(${receiver})"],
214 "requires": "std::rc::Rc",
215 "scope": "expr"
216 },
217 "Box::pin": {
218 "postfix": "boxpin",
219 "body": ["Box::pin(${receiver})"],
220 "requires": "std::boxed::Box",
221 "scope": "expr"
222 },
223 "vec!": {
224 "postfix": "vec",
225 "body": ["vec![${receiver}]"],
226 "description": "vec![]",
227 "scope": "expr"
228 }
229 }
230 }
231 }
232 }
233 }
234 }
235}
236```