Add some template arguments comments to debug output

Author: hsutter

source/parse.h

@@ -404,6 +404,8 @@ auto prefix_expression_node::visit(auto& v, int depth) -> void
 }
 
 
+struct template_args_tag { };
+
 struct unqualified_id_node
 {
     token const* identifier      = {};  // required
@@ -449,13 +451,16 @@ struct unqualified_id_node
         v.start(*identifier, depth+1);
 
         if (!template_args.empty()) {
+            //  Inform the visitor that this is a template args list
+            v.start(template_args_tag{}, depth);
             assert(open_angle  != source_position{});
             assert(close_angle != source_position{});
             assert(template_args.front().comma == source_position{});
             for (auto& a : template_args) {
                 try_visit<   expression>(a.arg, v, depth+1);
                 try_visit<id_expression>(a.arg, v, depth+1);
             }
+            v.end(template_args_tag{}, depth);
         }
 
         v.end(*this, depth);
@@ -3257,6 +3262,11 @@ class parse_tree_printer : printing_visitor
         o << pre(indent) << "function returns\n";
     }
 
+    auto start(template_args_tag const&, int indent) -> void
+    {
+        o << pre(indent) << "template arguments\n";
+    }
+
     auto start(declaration_node const& n, int indent) -> void
     {
         o << pre(indent) << "declaration\n";