Implementation propagation_const in prio C++17 version

It is the following example

#include <iostream>#include <memory>class B{    public:    void foo() const{        std::cout << "foo const" << std::endl;    }    void foo() {        std::cout << "foo non-const" << std::endl;    }};class A{    public:    void bar() const{        std::cout << "bar const" << std::endl;        b_->foo();    }    void bar() {        std::cout << "bar non-const" << std::endl;        b_->foo();    }    std::shared_ptr<B> b_{std::make_shared<B>()};};int main(){    A const a;    a.bar();}

Based on standard correctly the const is not propagated and foo non-const is called. My question how to implement propagation_const in version before C++17?