chore(parser): document possibly-buggy transactions

Author: strager

src/quick-lint-js/fe/parse-expression.cpp

@@ -992,6 +992,8 @@ expression* parser::parse_await_expression(parse_visitor_base& v,
 
         parser_transaction transaction = this->begin_transaction();
 
+        // FIXME(#831): v should not be used here. We should use a
+        // buffering_visitor.
         if (this->in_top_level_) {
           // Try to parse the / as a regular expression literal or the < as a
           // JSX element.

src/quick-lint-js/fe/parse-statement.cpp

@@ -3499,6 +3499,8 @@ void parser::parse_and_visit_let_bindings(parse_visitor_base &v,
           source_code_span in_token_span = this->peek().span();
           QLJS_ASSERT(!allow_in_operator);
 
+          // FIXME(#831): v should not be used here. We should use a
+          // buffering_visitor.
           this->try_parse(
               [&] {
                 expression *in_ast = this->parse_expression_remainder(