rust/docs/user

= User Manual
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// Master copy of this document lives in the https://github.com/rust-analyzer/rust-analyzer repository

At its core, rust-analyzer is a *library* for semantic analysis of Rust code as it changes over time.
This manual focuses on a specific usage of the library -- the implementation of
https://microsoft.github.io/language-server-protocol/[Language Server Protocol].
LSP allows various code editors, like VS Code, Emacs or Vim, to implement semantic features like completion or goto definition by talking to an external language server process.

To improve this document, send a pull request against
https://github.com/rust-analyzer/rust-analyzer/blob/master/docs/user/readme.adoc[this file].

== Installation

In theory, one should be able to just install the server binary and have it automatically work with any editor.
We are not there yet, so some editor specific setup is required.

Additionally, rust-analyzer needs sources of the standard library.
If the source code is not present, rust-analyzer will attempt to install it automatically.

To add the sources manually, run the following command:

```bash
$ rustup component add rust-src
```

=== VS Code

This is the best supported editor at the moment.
rust-analyzer plugin for VS Code is maintained
https://github.com/rust-analyzer/rust-analyzer/tree/master/editors/code[in tree].

You can install the latest release of the plugin from
https://marketplace.visualstudio.com/items?itemName=matklad.rust-analyzer[the marketplace].
By default, the plugin will prompt you to download the matching version of the server as well:

image::https://user-images.githubusercontent.com/9021944/75067008-17502500-54ba-11ea-835a-f92aac50e866.png[]

[NOTE]
====
To disable this notification put the following to `settings.json`

[source,json]
----
{ "rust-analyzer.updates.askBeforeDownload": false }
----
====

The server binary is stored in `~/.config/Code/User/globalStorage/matklad.rust-analyzer`.

Note that we only support the latest version of VS Code.

==== Updates

The extension will be updated automatically as new versions become available. It will ask your permission to download the matching language server version binary if needed.

===== Nightly

We ship nightly releases for VS Code. To help us out with testing the newest code and follow the bleeding edge of our `master`, please use the following config:

[source,json]
----
{ "rust-analyzer.updates.channel": "nightly" }
----

You will be prompted to install the `nightly` extension version. Just click `Download now` and from that moment you will get automatic updates each 24 hours.

If you don't want to be asked for `Download now` every day when the new nightly version is released add the following to your `settings.json`:
[source,json]
----
{ "rust-analyzer.updates.askBeforeDownload": false }
----

NOTE: Nightly extension should **only** be installed via the `Download now` action from VS Code.

==== Building From Source

Alternatively, both the server and the plugin can be installed from source:

[source]
----
$ git clone https://github.com/rust-analyzer/rust-analyzer.git && cd rust-analyzer
$ cargo xtask install
----

You'll need Cargo, nodejs and npm for this.

Note that installing via `xtask install` does not work for VS Code Remote, instead you'll need to install the `.vsix` manually.

==== Troubleshooting

Here are some useful self-diagnostic commands:

* **Rust Analyzer: Show RA Version** shows the version of `rust-analyzer` binary
* **Rust Analyzer: Status** prints some statistics about the server, like the few latest LSP requests
* To enable server-side logging, run with `env RUST_LOG=info` and see `Output > Rust Analyzer Language Server` in VS Code's panel.
* To log all LSP requests, add `"rust-analyzer.trace.server": "verbose"` to the settings and look for `Server Trace` in the panel.
* To enable client-side logging, add `"rust-analyzer.trace.extension": true` to the settings and open the `Console` tab of VS Code developer tools.

=== Language Server Binary

Other editors generally require `rust-analyzer` binary to be in `$PATH`.
You can download the pre-built binary from
https://github.com/rust-analyzer/rust-analyzer/releases[releases]
page, or you can install it from source using the following command:

[source,bash]
----
$ cargo xtask install --server
----

==== Arch Linux

`rust-analyzer` binary can be installed from AUR (Arch User Repository):

- https://aur.archlinux.org/packages/rust-analyzer-bin[`rust-analyzer-bin`] (binary from GitHub releases)
- https://aur.archlinux.org/packages/rust-analyzer[`rust-analyzer`] (built from latest tagged source)
- https://aur.archlinux.org/packages/rust-analyzer-git[`rust-analyzer-git`] (latest git version)

Install it with AUR helper of your choice, for example:

[source,bash]
----
$ yay -S rust-analyzer-bin
----

=== Emacs

Emacs support is maintained https://github.com/emacs-lsp/lsp-mode/blob/master/lsp-rust.el[upstream].

1. Install the most recent version of `emacs-lsp` package by following the instructions https://github.com/emacs-lsp/lsp-mode[here].
2. Set `lsp-rust-server` to `'rust-analyzer`.
3. Run `lsp` in a Rust buffer.
4. (Optionally) bind commands like `lsp-rust-analyzer-join-lines`, `lsp-extend-selection` and `lsp-rust-analyzer-expand-macro` to keys.

=== Vim

The are several LSP client implementations for vim:

==== coc-rust-analyzer

1. Install coc.nvim by following the instructions at
   https://github.com/neoclide/coc.nvim[coc.nvim]
   (nodejs required)
2. Run `:CocInstall coc-rust-analyzer` to install
   https://github.com/fannheyward/coc-rust-analyzer[coc-rust-analyzer],
   this extension implements _most_ of the features supported in the VSCode extension:
   * same configurations as VSCode extension, `rust-analyzer.serverPath`, `rust-analyzer.enableCargoWatchOnStartup` etc.
   * same commands too, `rust-analyzer.analyzerStatus`, `rust-analyzer.startCargoWatch` etc.
   * highlighting and inlay_hints are not implemented yet

==== LanguageClient-neovim

1. Install LanguageClient-neovim by following the instructions
   https://github.com/autozimu/LanguageClient-neovim[here]
   * The github project wiki has extra tips on configuration

2. Configure by adding this to your vim/neovim config file (replacing the existing Rust-specific line if it exists):
+
[source,vim]
----
let g:LanguageClient_serverCommands = {
\ 'rust': ['rust-analyzer'],
\ }
----

==== nvim-lsp

NeoVim 0.5 (not yet released) has built-in language server support.
For a quick start configuration of rust-analyzer, use https://github.com/neovim/nvim-lsp#rust_analyzer[neovim/nvim-lsp].
Once `neovim/nvim-lsp` is installed, use `+lua require'nvim_lsp'.rust_analyzer.setup({})+` in your `init.vim`.

=== Sublime Text 3

Prerequisites:

`LSP` package.

Installation:

1. Invoke the command palette with <kbd>Ctrl+Shift+P</kbd>
2. Type `LSP Settings` to open the LSP preferences editor
3. Add the following LSP client definition to your settings:
+
[source,json]
----
"rust-analyzer": {
    "command": ["rust-analyzer"],
    "languageId": "rust",
    "scopes": ["source.rust"],
    "syntaxes": [
        "Packages/Rust/Rust.sublime-syntax",
        "Packages/Rust Enhanced/RustEnhanced.sublime-syntax"
    ],
    "initializationOptions": {
      "featureFlags": {
      }
    },
}
----

4. You can now invoke the command palette and type LSP enable to locally/globally enable the rust-analyzer LSP (type LSP enable, then choose either locally or globally, then select rust-analyzer)

== Usage

See https://github.com/rust-analyzer/rust-analyzer/blob/master/docs/user/features.md[features.md].