gistfile1.cpp

#include <iostream>
#include <functional>
#include <vector>
using Cb = std::function<void()>;
using Cbs = std::vector<Cb>;

void print(Cbs& cbs)
{
  auto n = cbs.size();
  for(decltype(n) i = 0; i < n; ++i)
  {
    cbs.at(i)();
  }
  std::cout << std::endl;
}

int main()
{
  Cbs fs;
  fs.reserve(4); // Issue shows after this is exceeded

  int i = 42;
  fs.push_back([i, &fs]() {
    fs.push_back([i]() {
      std::cout << "x " << i  << std::endl;
    });
    std::cout << i << std::endl;
  });

  print(fs);
  print(fs);
  print(fs);
  print(fs);

  return 0;
}