Modules and using declaration: bug or feature?

[Wilhelm Meier <wilhelm.meier@xxxxxxxx>]

Hi all,

I have the following file:

m.h:
---
using test_t = unsigned char;
---

m1.cc
---
module;

#include "m.h"

export module m1;

export namespace M1 {
   using ::test_t;
}
---

and m2.cc:
---
module;

export module m2;

export import m1;

export namespace M1 {
   using x = test_t;
}
---

Compile the module interface unit m1.cc succeeds:

LANG=C g++ -c -std=c++23 -DNDEBUG -Os -fconcepts -fmodules-ts 
-fmodule-only -xc++ m1.cc

But compiling m2.cc fails:

LANG=C g++ -c -std=c++23 -DNDEBUG -Os -fconcepts -fmodules-ts 
-fmodule-only -xc++ m2.cc

m2.cc:8:19: error: 'test_t' does not name a type
8 |         using x = test_t;
|                   ^~~~~~
m2.cc:3:8: warning: not writing module 'm2' due to errors
3 | export module m2;
|        ^~~~~~

Is this a bug or a feature?

--
 Wilhelm