＜future＞注释14：函 _Make_associated_state (Alloc& )，promise＜Y＞的析构函数 ~promise ( ) 不会导致进程异常退出，-优快云博客

（44）函 _Make_associated_state (Alloc& )，本函数返回在堆区创建的 _Associated_state<_Ty> 对象的地址。本函数用于promise 的源代码中：

// construct an _Associated_state object with an allocator  用分配器构造 _Associated_state 对象
template <class _Ty, class _Alloc>  
_Associated_state<_Ty>*             // 注意本函数的返回值即可,在堆区创建 _Associated_state<_Ty> 对象
_Make_associated_state(const _Alloc& _Al) 
{
    using _Delty = _State_deleter<_Ty, _Associated_state<_Ty>, _Alloc>;
    using _Aldelty = _Rebind_alloc_t<_Alloc, _Delty>;                  //= _Alloc< _Delty >  凭经验
    using _Alstate = _Rebind_alloc_t<_Alloc, _Associated_state<_Ty>>;  //= _Alloc< _Associated_state<_Ty> > 

    _Aldelty _Del_alloc(_Al);   // 产生一个删除器
    _Alstate _State_alloc(_Al); // 用指定的分配器产生一个 _Associated_state<_Ty> 对象
    auto _Del = _Make_unique_alloc(_Del_alloc, _Al);                  //   _Del 和 _Res 是 unique_ptr 指针
    auto _Res = _Make_unique_alloc(_State_alloc, _Unfancy(_Del.get()));
/*
template <class _Ty, class _Dx >
class unique_ptr {      _Compressed_pair<_Dx, pointer> _Mypair;
    pointer get() { return _Mypair._Myval2; }
    pointer release() noexcept { return _STD exchange(_Mypair._Myval2, nullptr); }
};
*/
    (void)_Del.release();       // ownership of _Del.get() now transferred to _Res
    return _Unfancy(_Res.release()); // ownership transferred to caller
/*
template <class _Ptrty> // converts from a fancy pointer to a plain pointer
auto _Unfancy(_Ptrty _Ptr) noexcept { return _STD addressof(*_Ptr); } // 从智能指针转换为裸指针

template <class _Ty>    // do nothing for plain pointers
_Ty* _Unfancy(_Ty* _Ptr)   noexcept { return _Ptr;  }
*/
}