https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66892
--- Comment #11 from Jonathan Wakely <redi at gcc dot gnu.org> --- I wonder if it's really as simple as just removing the cp_parser_error. The C++11 change that resolved the issue is https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3259.htm and that looks more involved, if we wanted to accurately follow the correct grammar.
