hax.cpp

#include <utility>
#include <iostream>
#include <dlfcn.h>

int foo(char*, int*);

void* dl_handle;
void* get_sym(const char* name)
{
    void* s = dlsym(dl_handle, name);
    if (!s) {
        std::cerr << "dlsym failur";
        std::abort();
    }
    return s;
}

template<const char** name, typename T, T* F>
struct Resolver {};

template<const char** name, typename Ret, typename... Args, Ret (**F)(Args...)>
struct Resolver<name, Ret(*)(Args...), F> {
    static Ret run(Args... args)
    {
        *F = reinterpret_cast<Ret (*)(Args...)>(get_sym(*name));
        return (*F)(std::forward<Args>(args)...);
    }
};

static const char* _foo_name = "foo";
static decltype(&foo) _foo = Resolver<&_foo_name, decltype(&foo), &_foo>::run;