Conquer of Completion (CoC)

1. Install CoC
2. Install zig.vim
3. Install jsonc.vim (optional, so that comments in json are not highlighted as errors)
4. place the following snippet in your coc-settings.json (open it using :CocConfig)
5. place the following snippet in your init.lua / init.vim / .vimrc

// coc-settings.json
{
  // All nested settings will only affect Zig files.
  "[zig]": {
    // enable format-on-save from CoC + ZLS
    //
    // Formatting with ZLS matches `zig fmt`.
    // The Zig FAQ answers some questions about `zig fmt`:
    // https://github.com/ziglang/zig/wiki/FAQ
    "coc.preferences.formatOnSave": true,

    // Show inlay hints in the editor. Inlay hints are short annotations within the code,
    // which show variable types or parameter names.
    // "inlayHint.enable": true,

    // Use the language server to perform code highlighting
    "semanticTokens.enable": true
  },

  "languageserver": {
    "zls": {
      // use `"command": "zls"` if `zls` is in your PATH
      "command": "/path/to/zls_executable",
      "filetypes": [ "zig", "zon" ],
      // There are two ways to set config options:
      //   - edit your `zls.json` that applies to any editor that uses ZLS
      //   - set in-editor config options with the `settings` field below.
      //
      // Further information on how to configure ZLS:
      // https://zigtools.org/zls/configure/
      "settings": {
        // Whether to enable build-on-save diagnostics
        //
        // Further information about build-on save:
        // https://zigtools.org/zls/guides/build-on-save/
        // "zls.enable_build_on_save": true,

        // omit the following line if `zig` is in your PATH
        "zls.zig_exe_path": "/path/to/zig_executable"
      }
    }
  }
}

-- init.lua (Neovim only)

-- don't show parse errors in a separate window
vim.g.zig_fmt_parse_errors = 0
-- disable format-on-save from `ziglang/zig.vim`
vim.g.zig_fmt_autosave = 0

" init.vim or .vimrc

" don't show parse errors in a separate window
let g:zig_fmt_parse_errors = 0
" disable format-on-save from `ziglang/zig.vim`
let g:zig_fmt_autosave = 0

Code Actions on save

source.fixAll

-- init.lua (Neovim only)
vim.api.nvim_create_autocmd('BufWritePre',{
  pattern = {"*.zig", "*.zon"},
  command = "call CocActionAsync('fixAll')"
})

autocmd BufWritePre *.zig,*.zon call CocActionAsync('fixAll')

source.organizeImports

-- init.lua (Neovim only)
vim.api.nvim_create_autocmd('BufWritePre',{
  pattern = {"*.zig", "*.zon"},
  command = "call CocActionAsync('organizeImport')"
})

autocmd BufWritePre *.zig,*.zon call CocActionAsync('organizeImport')

Per-project config

Coc allows setting LSP settings per project via a .vim/coc-settings.json file. Use the :CocLocalConfig to create and open the settings file in your workspace folder. Run :h coc-configuration for more information.

If the use case for per-project config is to set the path to the Zig or ZLS executable, consider using direnv to add it to your $PATH or use a version manager for Zig and ZLS.