LibJS: Make sure private identifier is valid in optional chain

If we don't check that a private identifier is valid this can break the assumption that we have a private environment when evaluation the private identifier. Also an unknown private identifier this should be a SyntaxError.
Author: https://github.com/davidot Commit: 16ac43c9d4 Pull-request: https://github.com/SerenityOS/serenity/pull/16094 Reviewed-by: https://github.com/linusg
2025-08-10 10:09:14 +00:00 · 2022-11-17 10:24:20 +01:00 · 2022-11-17 10:24:20 +01:00 · 16ac43c9d4 · 2024-07-17 04:24:22 +09:00
commit 16ac43c9d4
parent 49fc0e2514
2 changed files with 38 additions and 0 deletions
--- a/Userland/Libraries/LibJS/Parser.cpp
+++ b/Userland/Libraries/LibJS/Parser.cpp
@ -3174,6 +3174,9 @@ NonnullRefPtr<OptionalChain> Parser::parse_optional_chain(NonnullRefPtr<Expressi
        } else if (match(TokenType::Period)) {
            consume();
            if (match(TokenType::PrivateIdentifier)) {
+                if (!is_private_identifier_valid())
+                    syntax_error(String::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
+
                auto start = position();
                auto private_identifier = consume();
                chain.append(OptionalChain::PrivateMemberReference {