https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79671
--- Comment #86 from Bernd Edlinger <bernd.edlinger at hotmail dot de> --- Created attachment 41101 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41101&action=edit another trial patch This is another approach for a patch that reflects what I understood so far what the C++17 spec wants from us. I think it should resolve the issue Richard raised.