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 -- running it as part of a server that implements the
https://microsoft.github.io/language-server-protocol/[Language Server Protocol] (LSP).
The 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 <<rust-analyzer-language-server-binary,`rust-analyzer` 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 the 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.
The 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` (Linux) or in `~/.Library/Application Support/Code/User/globalStorage/matklad.rust-analyzer` (macOS) or in `%APPDATA%\Code\User\globalStorage` (Windows).

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 every 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.

=== rust-analyzer Language Server Binary

Other editors generally require the `rust-analyzer` binary to be in `$PATH`.
You can download the pre-built binary from the https://github.com/rust-analyzer/rust-analyzer/releases[releases] page. Typically, you then need to rename the binary for your platform, e.g. `rust-analyzer-mac` if you're on Mac OS, to `rust-analyzer` and make it executable in addition to moving it into a directory in your `$PATH`.

On Linux to install the `rust-analyzer` binary into `~/.local/bin`, this commands could be used

[source,bash]
----
$ curl -L https://github.com/rust-analyzer/rust-analyzer/releases/latest/download/rust-analyzer-linux -o ~/.local/bin/rust-analyzer
$ chmod +x ~/.local/bin/rust-analyzer
----

Ensure `~/.local/bin` is listed in the `$PATH` variable.

Alternatively, you can install it from source using the following command:

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

If your editor can't find the binary even though the binary is on your `$PATH`, the likely explanation is that it doesn't see the same `$PATH` as the shell, see https://github.com/rust-analyzer/rust-analyzer/issues/1811[this issue]. On Unix, running the editor from a shell or changing the `.desktop` file to set the environment should help.

==== Arch Linux

The `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

Prerequisites: You have installed the <<rust-analyzer-language-server-binary,`rust-analyzer` binary>>.

Emacs support is maintained as part of the https://github.com/emacs-lsp/lsp-mode[Emacs-LSP] package in https://github.com/emacs-lsp/lsp-mode/blob/master/lsp-rust.el[lsp-rust.el].

1. Install the most recent version of `emacs-lsp` package by following the https://github.com/emacs-lsp/lsp-mode[Emacs-LSP instructions].
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

Prerequisites: You have installed the <<rust-analyzer-language-server-binary,`rust-analyzer` binary>>.

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]
   (Node.js 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:
   * automatically install and upgrade stable/nightly releases
   * same configurations as VSCode extension, `rust-analyzer.serverPath`, `rust-analyzer.cargo.features` etc.
   * same commands too, `rust-analyzer.analyzerStatus`, `rust-analyzer.ssr` etc.
   * inlay hints for method chaining support, _Neovim Only_
   * semantic highlighting is 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'],
\ }
----

==== YouCompleteMe

1. Install YouCompleteMe by following the instructions
  https://github.com/ycm-core/lsp-examples#rust-rust-analyzer[here]

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

==== ALE

To add the LSP server to https://github.com/dense-analysis/ale[ale]:

[source,vim]
----
call ale#linter#Define('rust', {
\   'name': 'rust-analyzer',
\   'lsp': 'stdio',
\   'executable': 'rust-analyzer',
\   'command': '%e',
\   'project_root': '.',
\})
----

==== 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: You have installed the <<rust-analyzer-language-server-binary,`rust-analyzer` binary>>.

You also need the `LSP` package. To install it:

1. If you've never installed a Sublime Text package, install Package Control:
   * Open the command palette (Win/Linux: `ctrl+shift+p`, Mac: `cmd+shift+p`)
   * Type `Install Package Control`, press enter
2. In the command palette, run `Package control: Install package`, and in the list that pops up, type `LSP` and press enter.

Finally, with your Rust project open, in the command palette, run `LSP: Enable Language Server In Project` or `LSP: Enable Language Server Globally`, then select `rust-analyzer` in the list that pops up to enable the rust-analyzer LSP. The latter means that rust-analyzer is enabled by default in Rust projects.

If it worked, you should see "rust-analyzer, Line X, Column Y" on the left side of the bottom bar, and after waiting a bit, functionality like tooltips on hovering over variables should become available.

If you get an error saying `No such file or directory: 'rust-analyzer'`, see the <<rust-analyzer-language-server-binary,`rust-analyzer` binary>> section on installing the language server binary.

== Usage

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