https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104993
Bug ID: 104993
Summary: [modules] Missing diagnostic when exporting
using-directive
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: johelegp at gmail dot com
Target Milestone: ---
[module.interface]p3s1 says
> An exported declaration that is not a module-import-declaration shall declare
> at least one name.
And its following example includes the line
> `export using namespace N; // error: does not declare a name`
https://godbolt.org/z/aGY9b6x66 shows Clang give a warning.
> mod.cpp:3:38: warning: ISO C++20 does not permit using directive to be
> exported [-Wexport-using-directive]
> export namespace y { using namespace x; }
> ^
> 1 warning generated.
GCC is silent: https://godbolt.org/z/zP6648s46.
Source:
```C++
export module mod;
export namespace x { int y; }
export namespace y { using namespace x; }
```
