Merge pull request #20141 from vigoux/ts-self-inherits

fix(treesitter): prevent endless loop on self-inheritence

docs(treesitter): suggest using extends to extend queries

runtime/doc/treesitter.txt

@@ -190,7 +190,7 @@ supported by Neovim.
 By default, the first query on `runtimepath` is used (which usually implies
 that user config takes precedence over plugins, which take precedence over
 queries bundled with Neovim). If a query should extend other queries instead
-of replacing them, use the `; extends` modeline below.
+of replacing them, use |ts-modeline-extends|.
 
 A `query` consists of one or more patterns. A `pattern` is defined over node
 types in the syntax tree.  A `match` corresponds to specific elements of the
@@ -199,16 +199,20 @@ and predicates. A `capture` allows you to associate names with a specific
 node in a pattern. A `predicate` adds arbitrary metadata and conditional data
 to a match.
 
+                                                           *ts-query-modeline*
 Neovim supports to customize the behavior of the queries using a set of
 "modelines", that is comments in the queries starting with `;`. Here are the
 currently supported modeline alternatives:
 
-    `inherits: {lang}...`
+    `inherits: {lang}...`                                 *ts-modeline-inherits*
         Specifies that this query should inherit the queries from {lang}.
         This will recursively descend in the queries of {lang} unless wrapped
         in parentheses: `({lang})`.
+        Note: this is meant to be used to include queries from another
+        language. If you want your query to extend the queries of the same
+        language, use `extends`.
 
-    `extends`
+    `extends`                                              *ts-modeline-extends*
         Specifies that this query should be used as an extension for the
         query, i.e. that it should be merged with the others.
         Note: the order of the extensions, and the query that will be used as

runtime/lua/vim/treesitter/query.lua

@@ -34,6 +34,18 @@ local function safe_read(filename, read_quantifier)
   return content
 end
 
+---@private
+--- Adds @p ilang to @p base_langs, only if @p ilang is different than @lang
+---
+---@return boolean true it lang == ilang
+local function add_included_lang(base_langs, lang, ilang)
+  if lang == ilang then
+    return true
+  end
+  table.insert(base_langs, ilang)
+  return false
+end
+
 --- Gets the list of files used to make up a query
 ---
 ---@param lang The language
@@ -84,10 +96,14 @@ function M.get_query_files(lang, query_name, is_included)
 
           if is_optional then
             if not is_included then
-              table.insert(base_langs, incllang:sub(2, #incllang - 1))
+              if add_included_lang(base_langs, lang, incllang:sub(2, #incllang - 1)) then
+                extension = true
+              end
             end
           else
-            table.insert(base_langs, incllang)
+            if add_included_lang(base_langs, lang, incllang) then
+              extension = true
+            end
           end
         end
       elseif modeline:match(EXTENDS_FORMAT) then