added some automation

lua/custom/plugins/lsp/clangd.lua

@@ -1,34 +1,52 @@
-return {
-  'neovim/nvim-lspconfig',
-  ft = { 'c', 'cpp', 'objc', 'objcpp', 'cuda' },
-  config = function()
-    local function build_cmd(commands_dir)
-      return {
+local M = {}
+
+M.clang_filetypes = { 'c', 'cpp', 'objc', 'objcpp', 'cuda' }
+
+local lspconfig = require 'lspconfig'
+
+local function find_compile_commands()
+  local lines = vim.fn.systemlist { 'fd', '-u', '-t', 'f', 'compile_commands.json' }
+  table.sort(lines, function(a, b)
+    return a:match 'debug' and not b:match 'debug'
+  end)
+  return vim.fn.fnamemodify(lines[1] or '', ':h')
+end
+
+function M.stop_clangd()
+  for _, client in ipairs(vim.lsp.get_clients()) do
+    if client.name == 'clangd' then
+      client.stop()
+    end
+  end
+end
+
+function M.setup_clangd(commands_dir)
+  M.stop_clangd()
+
+  lspconfig.clangd.setup {
+    cmd = {
       'clangd',
       '--background-index',
       '--clang-tidy',
       '--header-insertion=never',
       '--query-driver=' .. vim.fn.exepath 'clang++',
-        '--resource-dir=' .. vim.fn.trim(vim.fn.system 'clang++ --print-resource-dir'),
-        '--compile-commands-dir=' .. commands_dir,
-      }
-    end
-
-    local function reload_clangd(commands_dir)
-      commands_dir = commands_dir or './build/debug'
-      local lspconfig = require 'lspconfig'
-
-      lspconfig.clangd.setup {
-        cmd = build_cmd(commands_dir),
+      '--resource-dir=' .. vim.fn.systemlist({ 'clang++', '--print-resource-dir' })[1],
+      '--compile-commands-dir=' .. (commands_dir or '.'),
+    },
     root_dir = lspconfig.util.root_pattern '.git',
     single_file_support = true,
     capabilities = require('blink.cmp').get_lsp_capabilities(),
   }
 
-      vim.cmd.edit()
+  for _, bufnr in ipairs(vim.api.nvim_list_bufs()) do
+    local ft = vim.api.nvim_buf_get_option(bufnr, 'filetype')
+    if vim.tbl_contains(M.clang_filetypes, ft) then
+      vim.lsp.buf_attach_client(bufnr, vim.lsp.get_active_clients({ name = 'clangd' })[1].id)
     end
+  end
+end
 
-    local function pick_commands_dir()
+function M.pick_commands_dir()
   local pickers = require 'telescope.pickers'
   local finders = require 'telescope.finders'
   local conf = require('telescope.config').values
@@ -48,9 +66,35 @@ return {
       end,
     })
     :find()
-    end
+end
 
-    reload_clangd()
+function M.watch_compile_commands()
+  local uv = vim.uv or vim.loop
+  local watcher = uv.new_fs_event()
+  local cwd = vim.fn.getcwd()
+
+  watcher:start(
+    cwd,
+    { recursive = true },
+    vim.schedule_wrap(function(_, fname, status)
+      if fname and fname:match 'compile_commands%.json$' and status.change then
+        watcher:stop()
+        M.setup_clangd(vim.fn.fnamemodify(fname, ':h'))
+      end
+    end)
+  )
+end
+
+return {
+  'neovim/nvim-lspconfig',
+  ft = M.clang_filetypes,
+  config = function()
+    local dir = find_compile_commands()
+    if dir ~= '' then
+      M.setup_clangd(dir)
+    else
+      M.watch_compile_commands()
+    end
 
     vim.keymap.set('n', '<leader>cc', pick_commands_dir, { desc = 'Pick location of compile_commands.json for clangd' })
   end,