Sun, 29 Apr 2012 11:29:25 GMT

I should mention that the original test contained a hack to simplify the allocator's emulation. To demonstrate that the test is not based on false usage of the allocators API here follows a corrected version, which does not behave differently in regard to the relevant point:

#include "boost/function.hpp"
#include <memory>
#include <iostream>
struct F {
  static bool dothrow;
  unsigned char prevent_short_object_opt[sizeof(boost::detail::function::function_buffer) + 1];
  F(){}
  F(const F&) {
    if (dothrow)
      throw 0;
  }
  void operator()() {}
};
bool F::dothrow = false;
int alloc_cnt = 0;
template<class T>
struct my_alloc : std::allocator<T>
{
  my_alloc() : std::allocator<T>() {}
  template<class U>
  my_alloc(const my_alloc<U>& other) : std::allocator<T>(other) {}
  template<class Other>
  struct rebind
  {
    typedef my_alloc<Other> other;
  };
  void construct(typename std::allocator<T>::pointer p, const T& val)
  {
    F::dothrow = true;
    ::new((void *)p) T(val);
  }
  void deallocate(typename std::allocator<T>::pointer p,
	              typename std::allocator<T>::size_type n)
  {
    --alloc_cnt;
    std::cout << "deallocate: " << alloc_cnt << std::endl;
    return std::allocator<T>::deallocate(p, n);
  }
  typename std::allocator<T>::pointer allocate(typename std::allocator<T>::size_type n)
  {
    ++alloc_cnt;
    std::cout << "allocate: " << alloc_cnt << std::endl;
    return std::allocator<T>::allocate(n);
  }
};
int main() {
  F f;
  my_alloc<F> a;
  try {
    boost::function<void()> fu(f, a);
  } catch (int) {
    std::cout << "Caught expected - allocation count: " << alloc_cnt << std::endl;
  }
}

Boost C++ Libraries: Ticket #6844: [function] Memory leaks if used with allocator and throwing copy-c'tor of functor