Usually this error message is issued when semicolon is missing after the struct/class declaration.
Message itself is pretty obscure. It's better to change it: error: multiple types in one declaration, missing semicolon after type declaration? This will give users a clue and will likely eliminate the need to google the error message. -- Summary: Error message 'multiple types in one declaration' need to be reworded Product: gcc Version: 4.3.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: yuri at tsoft dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39281