Linker optimizing out shared library

Using CMake and gcc/clang compilers I want to create a shared library out of this file (Registrator.cpp):

#include ...

namespace
{

struct Registrator
{
    Registrator()
    {
        ...
    }
    ~Registrator()
    {
        ...
    }
} g_registrator [[gnu::used, gnu::visibility("default")]];

} // namespace

This object is not used anywhere else. Its responsibility is solely to do some things during its (de)construction.

When defining it as:

add_library(${libname} OBJECT Registrator.cpp)

It is a way to prevent the linker from optimizing out this TU as in OBJECT case all sources get into final executable.

However I want to be able to use this as a SHARED library as well. And in case of:

add_library(${libname} SHARED Registrator.cpp) 

the library is not linked at all, and gnu::visibility("default") unfortunately doesn't quite cut it.

Is there any way to achieve this? Thanks for help in advance.

Cheers :)