C++ lambda, undefined behavior - c++

Question

can someone tell me, why the following program fails?
#include <iostream>
#include <functional>
#include <vector>
#include <type_traits>
using namespace std;
template <bool is_enabled = true>
class Aggregator {
public:
Aggregator(std::function<char*()> data) : data(data) { }
void fun() {
for (uint32_t i = 0; i < 500; i++)
std::cout << *((int *)data() + i) << std::endl;
funInternal();
}
private:
template<bool enabled = is_enabled>
void funInternal(typename std::enable_if<enabled>::type* = 0) {
std::cout << "Feature is enabled!" << std::endl;
}
template<bool enabled = is_enabled>
void funInternal(typename std::enable_if<!enabled>::type* = 0) {
std::cout << "Feature is disabled!" << std::endl;
}
std::function<char*()> data;
};
template <typename T>
class Multivalue : public Aggregator<true> {
public:
Multivalue() : Aggregator<true>([&]() { return (char *) v.data(); }) { }
void add(T a) { v.push_back(a); }
private:
std::vector<T> v;
};
std::vector<Multivalue<int>> m;
int main() {
for (uint32_t i = 0; i < 100; i++)
m.push_back(Multivalue<int>());
for (uint32_t i = 0; i < 100; i++)
for (uint32_t j = 0; j < 1000; j++)
m[i].add(j);
for (uint32_t i = 0; i < 100; i++)
m[i].fun();
return 0;
}
I know that the code is not really beautiful, but I want to understand the problem there. Somehow, the lambda expression seems to make trouble.
Thanks,
Moo