Calling functions which receive shared_ptr<const TYPE>& or const shared_ptr<const TYPE>& doesn't work

[EugenCazacu]

Calling functions which receive shared_ptr<const TYPE>& or const shared_ptr<const TYPE>& doesn't work:

#include <iostream>
using namespace std;

#include "lua.hpp"

#define SOL_ALL_SAFETIES_ON 1
#include "sol3.hpp"

int main() {
    sol::state lua;
    lua.open_libraries(sol::lib::base);
    lua.set_function("intBuilder", []() -> shared_ptr<const int> { return make_shared<int>(10); });
    lua.set_function("intReader", [](shared_ptr<const int>& val) { cout << "intReader" << endl;} );
    lua.script(R"(
               print('hello from lua')
               local sharedInt = intBuilder()
               intReader(sharedInt)
               )");
    return 0;
}

The output I receive:

hello from lua
[sol2] An error occurred and has been passed to an error handler: sol: runtime error: stack index 1, expected userdata, received sol.sol::d::u<int>: unrecognized userdata (not pushed by sol?) (bad argument into 'void(std::shared_ptr<const int>&)')
stack traceback:
        [C]: in function 'base.intReader'
        [string "..."]:4: in main chunk
terminate called after throwing an instance of 'sol::error'
  what():  sol: runtime error: stack index 1, expected userdata, received sol.sol::d::u<int>: unrecognized userdata (not pushed by sol?) (bad argument into 'void(std::shared_ptr<const int>&)')
stack traceback:
        [C]: in function 'base.intReader'
        [string "..."]:4: in main chunk
Aborted (core dumped)

I use gcc 11.4.0 and sol2 v3.3.0 (revision eba8662), C++17.

For [v2.20.6] it's even worse as not even passing by value a shared_ptr<const TYPE> works.

I need to map some C++ interfaces to Lua and cannot change those interfaces. Many functions in those interfaces receive const shared_ptr<const TYPE>&.

For sol2 v3.3 I can work around this with a copy in a wrapped function and for 2.20.6, additionally I am wrapping the shared pointer into another struct and unwrapping that through the interfaces I need.

Can we get this fixed in the library or is there another 'simpler in some sense' way to work around this problem?
Am I missing something here?

Thank you