rust/docs/user/features.md

This documents is an index of features that rust-analyzer language server
provides. Shortcuts are for the default VS Code layout. If there's no shortcut,
you can use <kbd>Ctrl+Shift+P</kbd> to search for the corresponding action.

### Workspace Symbol <kbd>ctrl+t</kbd>

Uses fuzzy-search to find types, modules and function by name across your
project and dependencies. This is **the** most useful feature, which improves code
navigation tremendously. It mostly works on top of the built-in LSP
functionality, however `#` and `*` symbols can be used to narrow down the
search. Specifically,

- `Foo` searches for `Foo` type in the current workspace
- `foo#` searches for `foo` function in the current workspace
- `Foo*` searches for `Foo` type among dependencies, including `stdlib`
- `foo#*` searches for `foo` function among dependencies.

That is, `#` switches from "types" to all symbols, `*` switches from the current
workspace to dependencies.

### Document Symbol <kbd>ctrl+shift+o</kbd>

Provides a tree of the symbols defined in the file. Can be used to

* fuzzy search symbol in a file (super useful)
* draw breadcrumbs to describe the context around the cursor
* draw outline of the file

### On Typing Assists

Some features trigger on typing certain characters:

- typing `let =` tries to smartly add `;` if `=` is followed by an existing expression.
- Enter inside comments automatically inserts `///`
- typing `.` in a chain method call auto-indents

### Extend Selection

Extends the current selection to the encompassing syntactic construct
(expression, statement, item, module, etc). It works with multiple cursors. This
is a relatively new feature of LSP:
https://github.com/Microsoft/language-server-protocol/issues/613, check your
editor's LSP library to see if this feature is supported.

### Go to Definition

Navigates to the definition of an identifier.

### Go to Implementation

Navigates to the impl block of structs, enums or traits. Also implemented as a code lens.

### Go to Type Defintion

Navigates to the type of an identifier.

### Commands <kbd>ctrl+shift+p</kbd>

#### Run

Shows popup suggesting to run a test/benchmark/binary **at the current cursor
location**. Super useful for repeatedly running just a single test. Do bind this
to a shortcut!

#### Parent Module

Navigates to the parent module of the current module.

#### Matching Brace

If the cursor is on any brace (`<>(){}[]`) which is a part of a brace-pair,
moves cursor to the matching brace. It uses the actual parser to determine
braces, so it won't confuse generics with comparisons.

#### Join Lines

Join selected lines into one, smartly fixing up whitespace and trailing commas.

#### Show Syntax Tree

Shows the parse tree of the current file. It exists mostly for debugging
rust-analyzer itself.

#### Status

Shows internal statistic about memory usage of rust-analyzer

#### Run garbage collection

Manually triggers GC

#### Start Cargo Watch

Start `cargo watch` for live error highlighting. Will prompt to install if it's not already installed.

#### Stop Cargo Watch

Stop `cargo watch`

### Assists (Code Actions)

These are triggered in a particular context via light bulb. We use custom code on
the VS Code side to be able to position cursor. `<|>` signifies cursor

See [assists.md](./assists.md)

- Import path

```rust
// before:
impl std::fmt::Debug<|> for Foo {
}

// after:
use std::fmt::Debug;

impl Debug<|> for Foo {
}
```

### Magic Completions

In addition to usual reference completion, rust-analyzer provides some ✨magic✨
completions as well:

Keywords like `if`, `else` `while`, `loop` are completed with braces, and cursor
is placed at the appropriate position. Even though `if` is easy to type, you
still want to complete it, to get ` { }` for free! `return` is inserted with a
space or `;` depending on the return type of the function.

When completing a function call, `()` are automatically inserted. If function
takes arguments, cursor is positioned inside the parenthesis.

There are postifx completions, which can be triggerd by typing something like
`foo().if`. The word after `.` determines postifx completion, possible variants are:

- `expr.if` -> `if expr {}`
- `expr.match` -> `match expr {}`
- `expr.while` -> `while expr {}`
- `expr.ref` -> `&expr`
- `expr.refm` -> `&mut expr`
- `expr.not` -> `!expr`
- `expr.dbg` -> `dbg!(expr)`

There also snippet completions:

#### Inside Expressions

- `pd` -> `println!("{:?}")`
- `ppd` -> `println!("{:#?}")`

#### Inside Modules

- `tfn` -> `#[test] fn f(){}`

### Code highlighting

Experimental feature to let rust-analyzer highlight Rust code instead of using the
default highlighter.

#### Rainbow highlighting

Experimental feature that, given code highlighting using rust-analyzer is
active, will pick unique colors for identifiers.