Tomas Vik

Neovim native, built-in, LSP autocomplete

You don’t need nvim-cmp, coq_nvim, blink.cmp, or any of the other autocomplete plugins. Neovim supports LSP autocompletion without extra plugins, and this short post will show you how.

screencast

If you are only looking for the standard autocompletion offered by your Language Server, you can leverage the built-in lsp-completion.

Three easy steps

Step 1: set completeopt

Set the complete option to make the menu feel like the auto completion plugins.

-- prevent the built-in vim.lsp.completion autotrigger from selecting the first item
vim.opt.completeopt = { "menuone", "noselect", "popup" }

Explanation of the options taken from the docs:

  • menuone - Use the popup menu also when there is only one match. Useful when there is additional information about the match, e.g., what file it comes from.
  • noselect - Same as “noinsert”, except that no menu item is pre-selected. If both “noinsert” and “noselect” are present, “noselect” has precedence.
  • popup - Show extra information about the currently selected completion in a popup window. Only works in combination with “menu” or “menuone”. Overrides “preview”.

Step 2: enable completion on LSP client attach

I assume you already have nvim-lspconfig set up. If you do, you can pass in an on_attach callback when setting up each of the Language Servers.

See the following example:

require("lspconfig")["gopls"].setup({
	on_attach = function(client, bufnr)
      vim.lsp.completion.enable(true, client.id, bufnr, {
		autotrigger = true,
		convert = function(item)
          return { abbr = item.label:gsub("%b()", "") }
		end,
      })
      vim.keymap.set("i", "<C-space>", vim.lsp.completion.get, { desc = "trigger autocompletion" })
    end
})

The key part is the call to vim.lsp.completion.enable that will enable the completion. Using autotrigger makes the trigger characters automatically start completion.

I also mapped CTRL+SPACE to trigger the autocompletion. You can instead use omnicompletion with CTRL-X CTRL-O if you want to be a purist (omnicompletion is used under the hood).

In my dotfiles, I define on_attach once and reuse it for all setup() functions.

Step 3: Use it

Once the language client attaches, the autocompletion triggers on trigger characters like . and you can invoke it manually with CTRL+SPACE.

I’m excited to replace a plugin, but time will tell if this simplified version of autocompletion will be enough for me. I’m not sure how much I’ll miss the lack of snippets and documentation for each symbol.

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