On Sun, 18 Jun 2023 at 20:41, Smith, Jim via Std-Proposals <std-proposals@lists.isocpp.org> wrote:
Hi All,

Years ago I inquired about this, don't know if it was discussed further.

In some cases we might want to limit access for some types declared in a namespace.
Would it be feasible to at least add a private access specifier for Namespaces?

For example:

namespace Foo {
...
  private: {
       func() {}
   };
};

Would make func() accessible only inside the namespace.

What would that accomplish, given that any TU can reopen any namespace (pedantry: except std, etc) at any time?

Have you looked at modules?