https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102341
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
In fact it fails even with identical declarations:
export module test;
namespace Test
{
typedef long Long;
export typedef long Long;
}
mod.cc:5:23: error: conflicting exporting declaration 'Test::Long'
5 | export typedef long Long;
| ^~~~
mod.cc:4:16: note: previous declaration 'typedef long int Test::Long' here
4 | typedef long Long;
| ^~~~
mod.cc:1:8: warning: not writing module 'test' due to errors
1 | export module test;
| ^~~~~~
