[Bug c++/123728] Wsubobject-linkage warns despite no anonymous namespaces at all in a header

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123728

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Basically ParameterizedTestFactory<Test> does not have internal linkage as Test
does not internal linkage.

If another source file has:
```

namespace { struct LocalEnum {}; }

struct Test {
  typedef LocalEnum ParamType;
  static void AddToRegistry() {
    TestMetaFactory<Test> factory;
  }
};
```

Then TestMetaFactory<Test>::ParamType would have 2 different types as LocalEnum
in both TUs have internal linkage.