I was too lazy to fix this so instead I was filing a bug. Anyways DECL_MAIN_P is declared twice in cp-tree.h with the same definition. I don't know or when it happend but it does.
-- Summary: DECL_MAIN_P is declared twice in cp-tree.h Product: gcc Version: 4.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: pinskia at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24979