# Vim / Neovim

## AutoCompletion

For C++, anything that can use an LSP like {code}`coc.nvim`,
{code}`nvim-lspconfig`, or what not, should work as long as you generate a
{ref}`compilation database <compiledb-back-end-compileflags>` and point to it.

Additionally, [YouCompleteMe](https://github.com/ycm-core/YouCompleteMe/)
works without the need of a C++ compilation database as long as you have run
{code}`./mach build` or {code}`./mach configure`. Configuration for this lives
in {searchfox}`.ycm_extra_conf <.ycm_extra_conf>` at the root of the repo.

Rust auto-completion should work both with Rust's LSP {code}`rust-analyzer`.

Make sure that the LSP is configured in a way that it detects the root of the
tree as a workspace, not the crate you happen to be editing. For example, the
default of {code}`nvim-lspconfig` is to search for the closest
{code}`Cargo.toml` file, which is not what you want. You'd want something like:

```
root_dir = lspconfig.util.root_pattern(".git")
```

You also need to set some options to get full diagnostics:

```
"rust-analyzer.cargo.extraEnv": {
  "CARGO_TARGET_DIR": "/path/to/objdir"
},
"rust-analyzer.vfs.extraIncludes": ["/path/to/objdir", "/optional/path/to/windows_rs_dir"],
"rust-analyzer.check.overrideCommand": [ "/path/to/mach", "--log-no-times", "cargo", "check", "--all-crates", "--message-format-json" ],
"rust-analyzer.cargo.buildScripts.overrideCommand": [ "/path/to/mach", "--log-no-times", "cargo", "check", "--all-crates", "--message-format-json" ],
```

The easiest way to make these work out of the box is using
[codesettings.nvim](https://github.com/mrjones2014/codesettings.nvim), which
automatically supports importing VSCode configuration files.
{code}`./mach ide vscode --no-interactive` will then generate the right
configuration for you.

## ESLint

The easiest way to integrate ESLint with VIM is using the [Syntastic plugin](https://github.com/vim-syntastic/syntastic).

{code}`mach eslint --setup` installs a specific ESLint version and some ESLint
plugins into the repositories' {code}`node_modules`.

You need something like this in your {code}`.vimrc` to run the checker
automatically on save:

```
autocmd FileType javascript,html,xhtml let b:syntastic_checkers = ['javascript/eslint']
```

You need to have {code}`eslint` in your {code}`PATH`, which you can get with
{code}`npm install -g eslint`. You need at least version 6.0.0.

You can also use something like [eslint_d](https://github.com/mantoni/eslint_d.js#editor-integration) which should
also do that automatically:

```
let g:syntastic_javascript_eslint_exec = 'eslint_d'
```