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1
2Prerequisites:
3
4In order to build the VS Code plugin, you need to have node.js and npm with
5a minimum version of 10 installed. Please refer to
6[node.js and npm documentation](https://nodejs.org) for installation instructions.
7
8You will also need the most recent version of VS Code: we don't try to
9maintain compatibility with older versions yet.
10
11The experimental VS Code plugin can then be built and installed by executing the
12following commands:
13
14```
15$ git clone https://github.com/rust-analyzer/rust-analyzer.git --depth 1
16$ cd rust-analyzer
17$ cargo install-code
18
19# for stdlib support
20$ rustup component add rust-src
21```
22
23This will run `cargo install --package ra_lsp_server` to install the server
24binary into `~/.cargo/bin`, and then will build and install plugin from
25`editors/code`. See
26[this](https://github.com/rust-analyzer/rust-analyzer/blob/0199572a3d06ff66eeae85a2d2c9762996f0d2d8/crates/tools/src/main.rs#L150)
27for details. The installation is expected to *just work*, if it doesn't, report
28bugs!
29
30It's better to remove existing Rust plugins to avoid interference.
31
32## Rust Analyzer Specific Features
33
34These features are implemented as extensions to the language server protocol.
35They are more experimental in nature and work only with VS Code.
36
37### Syntax highlighting
38
39It overrides built-in highlighting, and works only with a specific theme
40(zenburn). `rust-analyzer.highlightingOn` setting can be used to disable it.
41
42### Go to symbol in workspace <kbd>ctrl+t</kbd>
43
44It mostly works on top of the built-in LSP functionality, however `#` and `*`
45symbols can be used to narrow down the search. Specifically,
46
47- `#Foo` searches for `Foo` type in the current workspace
48- `#foo#` searches for `foo` function in the current workspace
49- `#Foo*` searches for `Foo` type among dependencies, excluding `stdlib`
50- `#foo#*` searches for `foo` function among dependencies.
51
52That is, `#` switches from "types" to all symbols, `*` switches from the current
53workspace to dependencies.
54
55### Commands <kbd>ctrl+shift+p</kbd>
56
57#### Show Rust Syntax Tree
58
59Shows the parse tree of the current file. It exists mostly for debugging
60rust-analyzer itself.
61
62#### Extend Selection
63
64Extends the current selection to the encompassing syntactic construct
65(expression, statement, item, module, etc). It works with multiple cursors. Do
66bind this command to a key, its super-useful! Expected to be upstreamed to LSP soonish:
67https://github.com/Microsoft/language-server-protocol/issues/613
68
69#### Matching Brace
70
71If the cursor is on any brace (`<>(){}[]`) which is a part of a brace-pair,
72moves cursor to the matching brace. It uses the actual parser to determine
73braces, so it won't confuse generics with comparisons.
74
75#### Parent Module
76
77Navigates to the parent module of the current module.
78
79#### Join Lines
80
81Join selected lines into one, smartly fixing up whitespace and trailing commas.
82
83#### Run
84
85Shows popup suggesting to run a test/benchmark/binary **at the current cursor
86location**. Super useful for repeatedly running just a single test. Do bind this
87to a shortcut!
88
89
90### On Typing Assists
91
92Some features trigger on typing certain characters:
93
94- typing `let =` tries to smartly add `;` if `=` is followed by an existing expression.
95- Enter inside comments automatically inserts `///`
96- typing `.` in a chain method call auto-indents
97
98
99### Code Actions (Assists)
100
101These are triggered in a particular context via light bulb. We use custom code on
102the VS Code side to be able to position cursor.
103
104
105- Flip `,`
106
107```rust
108// before:
109fn foo(x: usize,<|> dim: (usize, usize))
110// after:
111fn foo(dim: (usize, usize), x: usize)
112```
113
114- Add `#[derive]`
115
116```rust
117// before:
118struct Foo {
119 <|>x: i32
120}
121// after:
122#[derive(<|>)]
123struct Foo {
124 x: i32
125}
126```
127
128- Add `impl`
129
130```rust
131// before:
132struct Foo<'a, T: Debug> {
133 <|>t: T
134}
135// after:
136struct Foo<'a, T: Debug> {
137 t: T
138}
139
140impl<'a, T: Debug> Foo<'a, T> {
141 <|>
142}
143```
144
145- Change visibility
146
147```rust
148// before:
149fn<|> foo() {}
150
151// after
152pub(crate) fn foo() {}
153```
154
155- Introduce variable:
156
157```rust
158// before:
159fn foo() {
160 foo(<|>1 + 1<|>);
161}
162
163// after:
164fn foo() {
165 let var_name = 1 + 1;
166 foo(var_name);
167}
168```
169
170- Replace if-let with match:
171
172```rust
173// before:
174impl VariantData {
175 pub fn is_struct(&self) -> bool {
176 if <|>let VariantData::Struct(..) = *self {
177 true
178 } else {
179 false
180 }
181 }
182}
183
184// after:
185impl VariantData {
186 pub fn is_struct(&self) -> bool {
187 <|>match *self {
188 VariantData::Struct(..) => true,
189 _ => false,
190 }
191 }
192}
193```
194
195- Split import
196
197```rust
198// before:
199use algo:<|>:visitor::{Visitor, visit};
200//after:
201use algo::{<|>visitor::{Visitor, visit}};
202```
203
204## LSP features
205
206* **Go to definition**: works correctly for local variables and some paths,
207 falls back to heuristic name matching for other things for the time being.
208
209* **Completion**: completes paths, including dependencies and standard library.
210 Does not handle glob imports and macros. Completes fields and inherent
211 methods.
212
213* **Outline** <kbd>alt+shift+o</kbd>
214
215* **Signature Info**
216
217* **Format document**. Formats the current file with rustfmt. Rustfmt must be
218 installed separately with `rustup component add rustfmt`.
219
220* **Hover** shows types of expressions and docstings
221
222* **Rename** works for local variables
223
224* **Code Lens** for running tests
225
226* **Folding**
227
228* **Diagnostics**
229 - missing module for `mod foo;` with a fix to create `foo.rs`.
230 - struct field shorthand
231 - unnecessary braces in use item
232
233
234## Performance
235
236Rust Analyzer is expected to be pretty fast. Specifically, the initial analysis
237of the project (i.e, when you first invoke completion or symbols) typically
238takes dozen of seconds at most. After that, everything is supposed to be more or
239less instant. However currently all analysis results are kept in memory, so
240memory usage is pretty high. Working with `rust-lang/rust` repo, for example,
241needs about 5 gigabytes of ram.