nvim/lua/plugins/lsp.lua

local on_attach = function(_, bufnr)
  local nmap = function(keys, func, desc)
    if desc then
      desc = 'LSP: ' .. desc
    end
    vim.keymap.set('n', keys, func, { buffer = bufnr, desc = desc })
  end

  local delayed_format = function()
    vim.lsp.buf.format { timeout_ms = 2000 }
  end

  nmap('<leader>rn', vim.lsp.buf.rename, '[R]e[n]ame')
  nmap('<leader>ca', vim.lsp.buf.code_action, '[C]ode [A]ction')
  nmap('<leader>ff', delayed_format, '[F]ormat')

  nmap('gd', vim.lsp.buf.definition, '[G]oto [D]efinition')
  nmap('gr', require('telescope.builtin').lsp_references, '[G]oto [R]eferences')
  nmap('gI', vim.lsp.buf.implementation, '[G]oto [I]mplementation')
  nmap('<leader>D', vim.lsp.buf.type_definition, 'Type [D]efinition')
  nmap('<leader>ds', require('telescope.builtin').lsp_document_symbols, '[D]ocument [S]ymbols')
  nmap('<leader>ws', require('telescope.builtin').lsp_dynamic_workspace_symbols, '[W]orkspace [S]ymbols')

  -- See `:help K` for why this keymap
  nmap('K', vim.lsp.buf.hover, 'Hover Documentation')
  nmap('<C-k>', vim.lsp.buf.signature_help, 'Signature Documentation')

  -- Lesser used LSP functionality
  nmap('gD', vim.lsp.buf.declaration, '[G]oto [D]eclaration')
  nmap('<leader>wa', vim.lsp.buf.add_workspace_folder, '[W]orkspace [A]dd Folder')
  nmap('<leader>wr', vim.lsp.buf.remove_workspace_folder, '[W]orkspace [R]emove Folder')
  nmap('<leader>wl', function()
    print(vim.inspect(vim.lsp.buf.list_workspace_folders()))
  end, '[W]orkspace [L]ist Folders')

  -- Create a command `:Format` local to the LSP buffer
  vim.api.nvim_buf_create_user_command(bufnr, 'Format', function(_)
    vim.lsp.buf.format()
  end, { desc = 'Format current buffer with LSP' })
end

return {
  {
    -- LSP Configuration & Plugins
    'neovim/nvim-lspconfig',
    dependencies = {
      -- Automatically install LSPs to stdpath for neovim
      'williamboman/mason.nvim',
      'williamboman/mason-lspconfig.nvim',

      -- adds extra functionality over rust_analyzer
      'simrat39/rust-tools.nvim',

      -- Useful status updates for LSP
      { 'j-hui/fidget.nvim', opts = {}, tag='legacy' },

      -- Additional lua configuration, makes nvim stuff amazing!
      'folke/neodev.nvim',
    },
    config = function()
      local servers = {
        clangd = {},
        gopls = {},
        marksman = {},
        pyright = {},
        tsserver = {},
        lua_ls = {
          Lua = {
            workspace = { checkThirdParty = false },
            telemetry = { enable = false },
          },
        },
      }

      -- Setup neovim lua configuration
      require('neodev').setup()

      -- nvim-cmp supports additional completion capabilities, so broadcast that to servers
      local capabilities = vim.lsp.protocol.make_client_capabilities()
      capabilities = require('cmp_nvim_lsp').default_capabilities(capabilities)

      -- Setup mason so it can manage external tooling
      require('mason').setup()

      -- Ensure the servers above are installed
      local mason_lspconfig = require 'mason-lspconfig'

      mason_lspconfig.setup {
        ensure_installed = vim.tbl_keys(servers),
      }

      mason_lspconfig.setup_handlers {
        function(server_name)
          require('lspconfig')[server_name].setup {
            capabilities = capabilities,
            on_attach = on_attach,
            settings = servers[server_name],
          }
        end,
      }

      local rust_tools_opts = {
        tools = {
          runnables = {
            use_telescope = true,
          },
          inlay_hints = {
            auto = true,
            show_parameter_hints = false,
            parameter_hints_prefix = '',
            other_hints_prefix = '',
          },
        },
        server = {
          on_attach = on_attach,
          settings = {
            ['rust-analyzer'] = {
              cargo = {
                -- always enable all features
                features = 'all',
              },
              -- use clippy on save
              checkOnSave = {
                command = 'clippy',
              },
            },
          },
        },
      }

      require('rust-tools').setup(rust_tools_opts)
    end,
  },
}