AFIO v1 style of C++ bitfields

v1.cpp

#include <stdio.h>

#define BOOST_AFIO_DECLARE_CLASS_ENUM_AS_BITFIELD(type) \
inline constexpr type operator&(type a, type b) \
{ \
    return static_cast<type>(static_cast<size_t>(a) & static_cast<size_t>(b)); \
} \
inline constexpr type operator&=(type a, type b) \
{ \
    return static_cast<type>(static_cast<size_t>(a) & static_cast<size_t>(b)); \
} \
inline constexpr type operator|(type a, type b) \
{ \
    return static_cast<type>(static_cast<size_t>(a) | static_cast<size_t>(b)); \
} \
inline constexpr type operator|=(type a, type b) \
{ \
    return static_cast<type>(static_cast<size_t>(a) | static_cast<size_t>(b)); \
} \
inline constexpr type operator~(type a) \
{ \
    return static_cast<type>(~static_cast<size_t>(a)); \
} \
inline constexpr bool operator!(type a) \
{ \
    return 0==static_cast<size_t>(a); \
}

enum class flag : size_t
{
  none=0,
  delete_on_close=1,
  disable_safety_fsyncs=2
};
BOOST_AFIO_DECLARE_CLASS_ENUM_AS_BITFIELD(flag)

int main(void)
{
  flag f(flag::disable_safety_fsyncs);
  flag f2(f&flag::none);
  f2|=flag::delete_on_close;
  constexpr flag f3(flag::disable_safety_fsyncs);
  constexpr flag f4(f3&flag::none);
  printf("f=%d, f2=%d, f3=%d, f4=%d\n", (unsigned) f, (unsigned) f2, (unsigned) f3, (unsigned) f4);
  return 0;
}