fix(treesitter): remove duplicate symbol names in language.inspect()

**Problems:**

- `vim.treesitter.language.inspect()` returns duplicate
  symbol names, sometimes up to 6 of one kind in the case of `markdown`
- The list-like `symbols` table can have holes and is thus not even a
  valid msgpack table anyway, mentioned in a test

**Solution:** Return symbols as a map, rather than a list, where field
names are the names of the symbol. The boolean value associated with the
field encodes whether or not the symbol is named.

Note that anonymous nodes are surrounded with double quotes (`"`) to
prevent potential collisions with named counterparts that have the same
identifier.

runtime/doc/treesitter.txt

@@ -1150,8 +1150,13 @@ get_lang({filetype})                      *vim.treesitter.language.get_lang()*
 inspect({lang})                            *vim.treesitter.language.inspect()*
     Inspects the provided language.
 
-    Inspecting provides some useful information on the language like node
+    Inspecting provides some useful information on the language like node and
-    names, ...
+    field names, ABI version, and whether the language came from a WASM
+    module.
+
+    Node names are returned in a table mapping each node name to a `boolean`
+    indicating whether or not the node is named (i.e., not anonymous).
+    Anonymous nodes are surrounded with double quotes (`"`).
 
     Parameters: ~
       • {lang}  (`string`) Language

runtime/lua/vim/treesitter/_query_linter.lua

@@ -240,8 +240,12 @@ function M.omnifunc(findstart, base)
       table.insert(items, text)
     end
   end
-  for _, s in pairs(parser_info.symbols) do
+  for text, named in
-    local text = s[2] and s[1] or string.format('%q', s[1]):gsub('\n', 'n') ---@type string
+    pairs(parser_info.symbols --[[@as table<string, boolean>]])
+  do
+    if not named then
+      text = string.format('%q', text:sub(2, -2)):gsub('\n', 'n') ---@type string
+    end
     if text:find(base, 1, true) then
       table.insert(items, text)
     end

runtime/lua/vim/treesitter/language.lua

@@ -170,7 +170,12 @@ end
 
 --- Inspects the provided language.
 ---
---- Inspecting provides some useful information on the language like node names, ...
+--- Inspecting provides some useful information on the language like node and field names, ABI
+--- version, and whether the language came from a WASM module.
+---
+--- Node names are returned in a table mapping each node name to a `boolean` indicating whether or
+--- not the node is named (i.e., not anonymous). Anonymous nodes are surrounded with double quotes
+--- (`"`).
 ---
 ---@param lang string Language
 ---@return table

src/nvim/lua/treesitter.c

@@ -271,12 +271,16 @@ int tslua_inspect_lang(lua_State *L)
       // not used by the API
       continue;
     }
-    lua_createtable(L, 2, 0);  // [retval, symbols, elem]
+    const char *name = ts_language_symbol_name(lang, (TSSymbol)i);
-    lua_pushstring(L, ts_language_symbol_name(lang, (TSSymbol)i));
+    bool named = t == TSSymbolTypeRegular;
-    lua_rawseti(L, -2, 1);
+    lua_pushboolean(L, named);  // [retval, symbols, is_named]
-    lua_pushboolean(L, t == TSSymbolTypeRegular);
+    if (!named) {
-    lua_rawseti(L, -2, 2);  // [retval, symbols, elem]
+      char buf[256];
-    lua_rawseti(L, -2, (int)i);  // [retval, symbols]
+      snprintf(buf, sizeof(buf), "\"%s\"", name);
+      lua_setfield(L, -2, buf);  // [retval, symbols]
+    } else {
+      lua_setfield(L, -2, name);  // [retval, symbols]
+    }
   }
 
   lua_setfield(L, -2, "symbols");  // [retval]

test/functional/treesitter/language_spec.lua

@@ -51,7 +51,7 @@ describe('treesitter language API', function()
   it('inspects language', function()
     local keys, fields, symbols = unpack(exec_lua(function()
       local lang = vim.treesitter.language.inspect('c')
-      local keys, symbols = {}, {}
+      local keys = {}
       for k, v in pairs(lang) do
         if type(v) == 'boolean' then
           keys[k] = v
@@ -60,12 +60,7 @@ describe('treesitter language API', function()
         end
       end
 
-      -- symbols array can have "holes" and is thus not a valid msgpack array
+      return { keys, lang.fields, lang.symbols }
-      -- but we don't care about the numbers here (checked in the parser test)
-      for _, v in pairs(lang.symbols) do
-        table.insert(symbols, v)
-      end
-      return { keys, lang.fields, symbols }
     end))
 
     eq({ fields = true, symbols = true, _abi_version = true, _wasm = false }, keys)
@@ -79,16 +74,19 @@ describe('treesitter language API', function()
     eq(true, fset['initializer'])
 
     local has_named, has_anonymous
-    for _, s in pairs(symbols) do
+    for symbol, named in pairs(symbols) do
-      eq('string', type(s[1]))
+      eq('string', type(symbol))
-      eq('boolean', type(s[2]))
+      eq('boolean', type(named))
-      if s[1] == 'for_statement' and s[2] == true then
+      if symbol == 'for_statement' and named == true then
         has_named = true
-      elseif s[1] == '|=' and s[2] == false then
+      elseif symbol == '"|="' and named == false then
         has_anonymous = true
       end
     end
-    eq({ true, true }, { has_named, has_anonymous })
+    eq(
+      { has_named = true, has_anonymous = true },
+      { has_named = has_named, has_anonymous = has_anonymous }
+    )
   end)
 
   it(

test/functional/treesitter/parser_spec.lua

@@ -42,13 +42,13 @@ describe('treesitter parser API', function()
     eq('function_definition', exec_lua('return child:type()'))
     eq(true, exec_lua('return child:named()'))
     eq('number', type(exec_lua('return child:symbol()')))
-    eq({ 'function_definition', true }, exec_lua('return lang.symbols[child:symbol()]'))
+    eq(true, exec_lua('return lang.symbols[child:type()]'))
 
     exec_lua('anon = root:descendant_for_range(0,8,0,9)')
     eq('(', exec_lua('return anon:type()'))
     eq(false, exec_lua('return anon:named()'))
     eq('number', type(exec_lua('return anon:symbol()')))
-    eq({ '(', false }, exec_lua('return lang.symbols[anon:symbol()]'))
+    eq(false, exec_lua([=[return lang.symbols[string.format('"%s"', anon:type())]]=]))
 
     exec_lua('descendant = root:descendant_for_range(1,2,1,12)')
     eq('<node declaration>', exec_lua('return tostring(descendant)'))