#include <mutex>
#include <iostream>
template<class Pointer,class Mutex>
struct lock_proxy {
    Pointer r;
    std::scoped_lock<Mutex> l;
    lock_proxy(Pointer rp,Mutex* m):r(rp),l(*m){}
    Pointer operator->() {
        return r;
    }
};
struct A{
    typedef std::mutex Mutex;
    Mutex m;
    void foo()
    {
        std::cout<<"world\n";
    }
};
template<class T>
struct LockPtr{
    typedef typename T::Mutex M;
    T* r;
    M* m;
    lock_proxy<T*, std::mutex> operator->(){
        return lock_proxy<T*, std::mutex> (r,m);
    }
};
int main()
{
    A a;
    LockPtr<A> lptr{&a,&a.m};
    lptr->foo();
}