feat(lsp): handle deprecated document symbols (#34751)

runtime/lua/vim/lsp/protocol.lua

@@ -144,6 +144,11 @@ local constants = {
     TypeParameter = 26,
   },
 
+  -- Extra annotations that tweak the rendering of a symbol.
+  SymbolTag = {
+    Deprecated = 1,
+  },
+
   -- Represents reasons why a text document is saved.
   TextDocumentSaveReason = {
     -- Manually triggered, e.g. by the user pressing save, by starting debugging,
@@ -525,6 +530,9 @@ function protocol.make_client_capabilities()
           valueSet = get_value_set(constants.SymbolKind),
         },
         hierarchicalDocumentSymbolSupport = true,
+        tagSupport = {
+          valueSet = get_value_set(constants.SymbolTag),
+        },
       },
       rename = {
         dynamicRegistration = true,

runtime/lua/vim/lsp/util.lua

@@ -1892,6 +1892,11 @@ function M.symbols_to_items(symbols, bufnr, position_encoding)
       local end_lnum = range['end'].line + 1
       local end_col = get_line_byte_from_position(bufnr, range['end'], position_encoding) + 1
 
+      local is_deprecated = symbol.deprecated
+        or (symbol.tags and vim.tbl_contains(symbol.tags, protocol.SymbolTag.Deprecated))
+      local text =
+        string.format('[%s] %s%s', kind, symbol.name, is_deprecated and ' (deprecated)' or '')
+
       items[#items + 1] = {
         filename = filename,
         lnum = lnum,
@@ -1899,7 +1904,7 @@ function M.symbols_to_items(symbols, bufnr, position_encoding)
         end_lnum = end_lnum,
         end_col = end_col,
         kind = kind,
-        text = '[' .. kind .. '] ' .. symbol.name,
+        text = text,
       }
     end