As per subject, the dll attributes can't be applied to c++ namespaces - this in fact applies to all windows platforms, not just cygwin. This would be a desirable mechanism for eliminating the use of auto-import by using explicit dllimport attributes, without having to uglify every header in the whole library to do so.
-- Summary: dll{im,ex}port attributes don't (yet) work on namespaces. Product: gcc Version: 4.5.0 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: davek at gcc dot gnu dot org GCC build triplet: i686-pc-cygwin GCC host triplet: i686-pc-cygwin GCC target triplet: i686-pc-cygwin http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42123