Parse parenteses correctly

corpus/parentheses.txt

@@ -0,0 +1,38 @@
+===================================================
+Parentheses inside command invocation [parentheses]
+===================================================
+message(STATUS (TEST))
+---
+(source_file
+  (normal_command
+    (identifier)
+    (argument (unquoted_argument))
+    (argument (unquoted_argument))
+  )
+)
+
+===========================================================
+Missing parentheses inside command invocation [parentheses]
+===========================================================
+message(STATUS (TEST)
+---
+(source_file
+  (normal_command
+    (identifier)
+    (argument (unquoted_argument))
+    (argument (unquoted_argument)) (MISSING ")")
+  )
+)
+
+==================================================================
+Nested missing parentheses inside command invocation [parentheses]
+==================================================================
+message(STATUS ((TEST))
+---
+(source_file
+  (normal_command
+    (identifier)
+    (argument (unquoted_argument))
+    (argument (unquoted_argument)) (MISSING ")")
+  )
+)

grammar.js

@@ -34,7 +34,8 @@ module.exports = grammar({
     cache_var: ($) => seq("$", "CACHE", "{", $.variable, "}"),
 
     argument: ($) => choice($.bracket_argument, $.quoted_argument, $.unquoted_argument),
-    _untrimmed_argument: ($) => choice(/\s/, $.bracket_comment, $.line_comment, $.argument),
+    _untrimmed_argument: ($) => choice(/\s/, $.bracket_comment, $.line_comment, $.argument, $._paren_argument),
+    _paren_argument: ($) => seq("(", $._untrimmed_argument, ")"),
 
     quoted_argument: ($) => seq('"', optional($.quoted_element), '"'),
     quoted_element: ($) => repeat1(choice($.variable_ref, /[^\\"]/, $.escape_sequence)),

src/grammar.json

@@ -197,6 +197,27 @@
         {
           "type": "SYMBOL",
           "name": "argument"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "_paren_argument"
+        }
+      ]
+    },
+    "_paren_argument": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "("
+        },
+        {
+          "type": "SYMBOL",
+          "name": "_untrimmed_argument"
+        },
+        {
+          "type": "STRING",
+          "value": ")"
         }
       ]
     },