Autocompletion

Autocompletion (not built-in) vs. completion (built-in)

Neovim does not support built-in autocompletion. As mentioned in the readme, you can bind the completion results to omnifunc for on-demand completion. To use autocompletion, please use an external plugin. We recommend nvim-cmp, the successor/rewrite of nvim-compe.

Please note, in order to provide completion, text must be synchronized on each completion request. If you notice slowdowns, the most likely candidate is a slow language server bottlenecking your autocompletion plugin.

nvim-cmp

For installing nvim-cmp, with autocompletion support for snippets/LSP, you can follow the below snippet. Note, this does not include your server configuration. If you are using nvim-cmp do not use neovim's built-in omnifunc as it cannot support the additional completion items returned from servers due to the capabilities enabled by nvim-cmp.

local use = require('packer').use
require('packer').startup(function()
  use 'neovim/nvim-lspconfig' -- Collection of configurations for built-in LSP client
  use 'hrsh7th/nvim-cmp' -- Autocompletion plugin
  use 'hrsh7th/cmp-nvim-lsp' -- LSP source for nvim-cmp
  use 'saadparwaiz1/cmp_luasnip' -- Snippets source for nvim-cmp
  use 'L3MON4D3/LuaSnip' -- Snippets plugin
end)

-- Add additional capabilities supported by nvim-cmp
local capabilities = vim.lsp.protocol.make_client_capabilities()
capabilities = require('cmp_nvim_lsp').update_capabilities(capabilities)

local lspconfig = require('lspconfig')

-- Enable some language servers with the additional completion capabilities offered by nvim-cmp
local servers = { 'clangd', 'rust_analyzer', 'pyright', 'tsserver' }
for _, lsp in ipairs(servers) do
  lspconfig[lsp].setup {
    -- on_attach = my_custom_on_attach,
    capabilities = capabilities,
  }
end

-- luasnip setup
local luasnip = require 'luasnip'

-- nvim-cmp setup
local cmp = require 'cmp'
cmp.setup {
  snippet = {
    expand = function(args)
      require('luasnip').lsp_expand(args.body)
    end,
  },
  mapping = {
    ['<C-p>'] = cmp.mapping.select_prev_item(),
    ['<C-n>'] = cmp.mapping.select_next_item(),
    ['<C-d>'] = cmp.mapping.scroll_docs(-4),
    ['<C-f>'] = cmp.mapping.scroll_docs(4),
    ['<C-Space>'] = cmp.mapping.complete(),
    ['<C-e>'] = cmp.mapping.close(),
    ['<CR>'] = cmp.mapping.confirm {
      behavior = cmp.ConfirmBehavior.Replace,
      select = true,
    },
    ['<Tab>'] = function(fallback)
      if cmp.visible() then
        cmp.select_next_item()
      elseif luasnip.expand_or_jumpable() then
        luasnip.expand_or_jump()
      else
        fallback()
      end
    end,
    ['<S-Tab>'] = function(fallback)
      if cmp.visible() then
        cmp.select_prev_item()
      elseif luasnip.jumpable(-1) then
        luasnip.jump(-1)
      else
        fallback()
      end
    end,
  },
  sources = {
    { name = 'nvim_lsp' },
    { name = 'luasnip' },
  },
}

Auto-import

The above snippet maps the necessary confirm on enter mapping to use auto-import. An example to show how this works:

1. Make sure tsserver is installed according to the lspconfig wiki, and if you want, use our autocompletion example init.lua.
2. mkdir test && cd test && npm init
3. Follow the prompts to create a project
4. npm install lodash --save
5. npm install @types/lodash --save-dev
6. echo import { } from "lodash" >> index.js
7. nvim index.js
8. Check the language server is running with :LspInfo
9. type debounce on line 2 and hit enter (<CR>)

Note: This currently does not work with typescript server (theia) on Windows due to an upstream bug in theia, see https://github.com/theia-ide/typescript-language-server/issues/135

coq_nvim

coq_nvim requires wrapping the config table passed to setup {}. See the example below:

local use = require('packer').use
require('packer').startup(function()
  use 'neovim/nvim-lspconfig' -- Collection of configurations for built-in LSP client
  use 'ms-jpq/coq_nvim'
  use 'ms-jpq/coq.artifacts'
  use 'ms-jpq/coq.thirdparty'
end)

local lspconfig = require('lspconfig')

-- Enable some language servers with the additional completion capabilities offered by nvim-cmp
local servers = { 'clangd', 'rust_analyzer', 'pyright', 'tsserver' }
for _, lsp in ipairs(servers) do
  lspconfig[lsp].setup(require('coq').lsp_ensure_capabilities({
    -- on_attach = my_custom_on_attach,
  }))
end