neovim rust important bits

init.lua

-- I use packer to manage my plugins

require('packer').startup(function() {
  -- treesitter configs (treesitter enables neovim to parse buffers into ASTs.
  -- it's built in, but there's an official helper library to help set it up)
	use {
		'nvim-treesitter/nvim-treesitter',
		run = function() require('nvim-treesitter.install').update{ with_sync = true } end,
	}
  -- treesitter --> text objects
  -- (e.g. cia --> change inside argument)
	use 'nvim-treesitter/nvim-treesitter-textobjects'


	-- lsp goodness (manage lanuage server setup)
	use 'neovim/nvim-lspconfig' -- helpers to set up different language servers
	use 'mfussenegger/nvim-dap' -- debugger support

  -- telescope is a *really* nice framework for doing fuzzy finders
  -- (text search, AST search with treesitter, symbol search with LSP, files & open buffers, etc)
	use {
		'nvim-telescope/telescope.nvim',
		requires = {{'nvim-lua/popup.nvim'}, {'nvim-lua/plenary.nvim'}}
	}
})
  
-- turn on treesitter
require('nvim-treesitter.configs').setup {
	highlight = {
		enable = true,
	},
	
	textobjects = {
		-- select by parameter
		select = {
			enable = true,
			keymaps = {
				["ia"] = "@parameter.inner",
				["aa"] = "@parameter.outer",
				["if"] = "@function.inner",
			},
		},
		-- move between parameters and such
		move = {
			enable = true,
			set_jumps = true,
			goto_next_start = {
				["]m"] = "@function.outer",
				["]a"] = "@parameter.inner",
			},
			goto_next_end = {
				["]M"] = "@function.outer",
				["]A"] = "@parameter.outer",
			},
			goto_previous_start = {
				["[m"] = "@function.outer",
				["[a"] = "@parameter.inner",
			},
			goto_previous_end = {
				["[M"] = "@function.outer",
				["[A"] = "@parameter.outer",
			},
		},
	},
}

-- enable telescope
require('telescope').setup()

-- lsp stuff
local lspconfigs = require('lspconfig.configs')
local lspconfig = require('lspconfig')

local lsp_attach_advanced = function(client, bufnum, skip_rust_specials)
	local opts = { noremap = true, silent = true, buffer=bufnum }
  
  -- real basic autocomplete (you probably want a better setup -- see the nvim-lspconfigs repo for more details)
	vim.api.nvim_buf_set_option(bufnum, 'omnifunc', 'v:lua.vim.lsp.omnifunc')

	-- definition & hover via normal keybinds...
	vim.keymap.set('n', 'gd', vim.lsp.buf.definition, opts)
	vim.keymap.set('n', 'gD', vim.lsp.buf.declaration, opts)
	if not skip_rust_specials then
		vim.keymap.set('n', 'K', vim.lsp.buf.hover, opts)
	end

	vim.keymap.set('n', '<leader>gi', vim.lsp.buf.implementation, opts)
	-- TODO: these are default bindings, they need some tweaking
	vim.keymap.set('n', '<C-k>', vim.lsp.buf.signature_help, opts)
	vim.keymap.set('n', '<leader>D', vim.lsp.buf.type_definition, opts)
	-- ... and refs & symbols via telescope
	vim.keymap.set('n', 'gr', require('telescope.builtin').lsp_references, opts)
	vim.keymap.set('n', '<space>fs', require('telescope.builtin').lsp_document_symbols, opts)
	vim.keymap.set('n', '<space>fws', require('telescope.builtin').lsp_dynamic_workspace_symbols, opts)

	vim.keymap.set('n', '<leader>=', function() vim.lsp.buf.format { async = true } end, opts)

	vim.keymap.set('n', '<leader>rn', vim.lsp.buf.rename, opts) -- TODO: unify with treesitter rename?
	vim.keymap.set('n', '<leader>ca', vim.lsp.buf.code_action, opts)

	-- diagnostics
	vim.keymap.set('n', '<leader>e', vim.diagnostic.open_float, opts)
	vim.keymap.set('n', '[d', vim.diagnostic.goto_prev, opts)
	vim.keymap.set('n', ']d', vim.diagnostic.goto_next, opts)
	vim.keymap.set('n', '<space>q', vim.diagnostic.setloclist, opts)
end

-- sets up rust LSP itself 
require('rust-tools').setup{
	server = { -- would be passed to LSP config
		cmd = {"rustup", "run", "nightly", "rust-analyzer"},
		on_attach = function(client, buffnum)
			lsp_attach_advanced(client, buffnum, true)

			local opts = { noremap = true, silent = true, buffer=bufnum }
			vim.keymap.set('n', '<leader>cga', require'rust-tools'.code_action_group.code_action_group, opts)
			vim.keymap.set('n', 'K', require'rust-tools'.hover_actions.hover_actions, opts)
			vim.keymap.set('n', '<leader>s', require'rust-tools'.ssr.ssr, opts)
			vim.keymap.set('n', '<leader>do', require'rust-tools'.external_docs.open_external_docs, opts)

		end,
		settings = {
			["rust-analyzer"] = {
				assist = {
					importGranularity = "module",
					importPrefix = "by_self",
				},
				cargo = {
					loadOutDirsFromCheck = true,
				},
				procMacro = {
					enable = true,
				},
				checkOnSave = {
					command = "clippy",
				},
			}
		},
	},
	dap = {
		adapter = {
			command = '/path/to/lldb-vscode',
		},
	},
}
  
---- keymapings ----
vim.g.mapleader = " " -- <Space>

-- telescope shortcuts for fuzzy-finding
function ivy()
	return require('telescope.themes').get_ivy({})
end

local telescope = function() return require('telescope.builtin') end
map_key('n', '<leader>ff', '', { noremap = true, callback = function() telescope().find_files(ivy()) end })
map_key('n', '<leader>fg', '', { noremap = true, callback = function() telescope().live_grep(ivy()) end })
map_key('n', '<leader>fb', '', { noremap = true, callback = function() telescope().buffers(ivy()) end })
map_key('n', '<leader>fh', '', { noremap = true, callback = function() telescope().help_tags() end })
map_key('n', '<leader>ft', '', { noremap = true, callback = function() telescope().treesitter(ivy()) end })

-- debug adapter
map_key('n', '<leader>db', [[<cmd>lua require'dap'.toggle_breakpoint()<CR>]], { noremap = true })
map_key('n', '<leader>dc', [[<cmd>lua require'dap'.continue()<CR>]], { noremap = true })
map_key('n', '<leader>dso', [[<cmd>lua require'dap'.step_over()<CR>]], { noremap = true })
map_key('n', '<leader>dr', [[<cmd>lua require'dap'.repl.open()<CR>]], { noremap = true })