feat(clangd): add symbolInfo support

Signed-off-by: Dimitris Dimitropoulos <dimitris.dimitropoulos00@gmail.com>

lua/lspconfig/server_configurations/clangd.lua

@@ -21,6 +21,34 @@ local function switch_source_header(bufnr)
   end
 end
 
+local function symbol_info(bufnr)
+  bufnr = util.validate_bufnr(bufnr)
+  local clangd_client = util.get_active_client_by_name(bufnr, 'clangd')
+  if not clangd_client then
+    return vim.notify('Clangd client not found', vim.log.levels.ERROR)
+  end
+  local pos = vim.api.nvim_win_get_cursor(0)
+  vim.lsp.buf_request(0, 'textDocument/symbolInfo', {
+    textDocument = { uri = vim.uri_from_bufnr(0) },
+    position = { line = pos[1] - 1, character = pos[2] },
+  }, function(err, res)
+    if err or #res == 0 then
+      -- Clangd always returns an error, there is not reason to parse it
+      return
+    end
+    local container = string.format('container: %s', res[1].containerName) ---@type string
+    local name = string.format('name: %s', res[1].name) ---@type string
+    vim.lsp.util.open_floating_preview({ name, container }, '', {
+      height = 2,
+      width = math.max(string.len(name), string.len(container)),
+      focusable = false,
+      focus = false,
+      border = require('lspconfig.ui.windows').default_options.border or 'single',
+      title = 'Symbol Info',
+    })
+  end)
+end
+
 local root_files = {
   '.clangd',
   '.clang-tidy',
@@ -56,6 +84,12 @@ return {
       end,
       description = 'Switch between source/header',
     },
+    ClangdShowSymbolInfo = {
+      function()
+        symbol_info(0)
+      end,
+      description = 'Show symbol info',
+    },
   },
   docs = {
     description = [[