Configure neovim for rust development

nvim's 0.5.0 release includes a native lsp-client: nvim-lsp.

I have toyed with neovim for a while as a long time vim user and decided to make the switch proper. This is my current setup, and a little advice on putting all the pieces together.

First of all, the vim config:

init.vim

call plug#begin()
Plug 'neovim/nvim-lsp'
Plug 'Shougo/deoplete.nvim', { 'do': ':UpdateRemotePlugins' }
Plug 'Shougo/deoplete-lsp'
Plug 'ervandew/supertab'
Plug 'Chiel92/vim-autoformat'
call plug#end()

" setup rust_analyzer LSP (IDE features)
lua require'nvim_lsp'.rust_analyzer.setup{}

" Use LSP omni-completion in Rust files
autocmd Filetype rust setlocal omnifunc=v:lua.vim.lsp.omnifunc

" Enable deoplete autocompletion in Rust files
let g:deoplete#enable_at_startup = 1

" customise deoplete                                                                                                                                                     " maximum candidate window length
call deoplete#custom#source('_', 'max_menu_width', 80)

" Press Tab to scroll _down_ a list of auto-completions
let g:SuperTabDefaultCompletionType = "<c-n>"

" rustfmt on write using autoformat
autocmd BufWrite * :Autoformat

"TODO: clippy on write
autocmd BufWrite * :Autoformat

nnoremap <leader>c :!cargo clippy

There's a fair amount going on here, but all of this is related to helping format, lint and auto-complete rust code.

I'm using rust for this example because I am loving learning rust at the moment but there are many supported languages - if you are setting yourself up for a different language (JS, python and others), try letting
nvim-lsp install the language server for you. We'll be compiling the language server from source (don't worry, cargo makes it a breeze).

Installs

First of all, nvim-lsp at the time of writing is new, and you need at least version 0.5.0 of nvim installed. Your current install is probably stable like mine was, which isn't new enough. So grab 0.5.0, tar -xzf and whack it somewhere in your path, like this (on linux):

tar -xzf nvim-linux64.tar.gz
sudo cp nvim-linux64/bin/nvim /usr/bin/nvim
nvim # this should load up 0.5.0

If you don't have nvim 0.5.0 or greater nvim-lsp won't exist, let alone work!

nvim-lsp and autoformat rely on external tooling to work their magic, so let's get it installed.

In your shell, from the top.

# install rust
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

# install rustfmt (for formatting)
rustup component add rustfmt

# install clippy (for semantic linting)
rustup component add clippy

# hardest one last, install rust-analyzer
git clone https://github.com/rust-analyzer/rust-analyzer && cd rust-analyzer
cargo xtask install --server

To check it worked (your commit hash will likely vary!)

$ ra_lsp_server --version
rust-analyzer 823c152

Back in the world of vim plugins, start up nvim and install your plugins. If you have vim-plug that's as easy as

(inside nvim)
:PlugInstall

If you don't, it's just (in your shell)

curl -fLo ~/.local/share/nvim/site/autoload/plug.vim --create-dirs \
    https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim

nvim

and then :PlugInstall as above. If you don't use vim-plug and don't know what a vim plugin manager is, my advice is simple: vim-plug is easily good enough and so simple. I highly recommend it.

Depending on the state of your nvim install, you might need a python module called pynvim. I think deoplete needs this.

pip install pynvim

Now you can edit some rust code!

• auto-completion should just appear (use tab to choose a suggestion, thanks supertab)
• run clippy by pressing <leader>c (in this case -c)
• on each write, your code will be formatted using rustfmt (never argue about code style again)
• Enjoy!

Let me know if you try this and run into issues and I'll update (m)any mistakes.

Would love to hear what nvim setup you are running, particularly for rust programming. I have loads to learn so let me know what you think, good or bad.