test.cpp

#include <functional>
#include <iostream>

template <class F>
struct wrapper {
	wrapper(F&& f) 
        : f(std::forward<F>(f)) { }
            
	std::decay_t<F> f;
};

template <class F>
decltype(auto) make_wrapper(F&& f) {
	return wrapper<F>(std::forward<F>(f));
}

decltype(auto) test_lambda() {
	auto s = std::string("hello");
	auto l = [s]()->void {
		std::cout << s.c_str() << std::endl;
	};
	auto c = l;
	return c;
}

decltype(auto) test_wrapper() {
	auto s = std::string("hello");
	auto c = [s]()->void {
		std::cout << s.c_str() << std::endl;
	};
	return make_wrapper(c);
}

int main()
{
	auto l = test_lambda();
	l();

	auto w = test_wrapper();
	w.f();

    return 0;
}