c – 奇怪的错误：当没有真正创建指针时使用已删除的函数’std :

template<typename T>
    using VectorPtr=std::vector<std::unique_ptr<T>>;

    template<typename T>
    using VectorRawPtr=std::vector<T*>;

    class ItemsSet{ // <-- Compiler say this line contans an error 0_o ?
    public:
          ItemsSet(VectorPtr<Item>& items);  

          ~ItemsSet() = default;

           VectorRawPtr<Item> GetItems();

           VectorRawPtr<Item> GetSuitableItemsForPeriod(const IPeriod &period);

           double CalculateTotal();
    private:
       VectorPtr<Item> _items;
    };

构造函数看起来像：

ItemsSet::ItemsSet(VectorPtr<Item> & items) {
     for(auto &itm: items){
        _items.emplace_back(std::move(itm));
     }
}

但是这段代码没有编译并因错误而失败：

/usr/lib/gcc/x86_64-pc-cygwin/5.4.0/include/c++/bits/stl_construct.h: In instantiation of 'void std::_Construct(_T1*,_Args&& ...) [with _T1 = std::unique_ptr<Item,std::default_delete<Item> >; _Args = {const std::unique_ptr<Item,std::default_delete<Item> >&}]':
/usr/lib/gcc/x86_64-pc-cygwin/5.4.0/include/c++/bits/stl_uninitialized.h:75:18:   required from 'static _ForwardIterator std::__uninitialized_copy<_TrivialValueTypes>::__uninit_copy(_InputIterator,_InputIterator,_ForwardIterator) [with _InputIterator = __gnu_cxx::__normal_iterator<const std::unique_ptr<Item,std::default_delete<Item> >*,std::vector<std::unique_ptr<Item,std::default_delete<Item> >,std::allocator<std::unique_ptr<Item,std::default_delete<Item> > > > >; _ForwardIterator = std::unique_ptr<Item,std::default_delete<Item> >*; bool _TrivialValueTypes = false]'
/usr/lib/gcc/x86_64-pc-cygwin/5.4.0/include/c++/bits/stl_uninitialized.h:126:15:   required from '_ForwardIterator std::uninitialized_copy(_InputIterator,std::default_delete<Item> >*]'
/usr/lib/gcc/x86_64-pc-cygwin/5.4.0/include/c++/bits/stl_uninitialized.h:281:37:   required from '_ForwardIterator std::__uninitialized_copy_a(_InputIterator,_ForwardIterator,std::allocator<_Tp>&) [with _InputIterator = __gnu_cxx::__normal_iterator<const std::unique_ptr<Item,std::default_delete<Item> >*; _Tp = std::unique_ptr<Item,std::default_delete<Item> >]'
/usr/lib/gcc/x86_64-pc-cygwin/5.4.0/include/c++/bits/stl_vector.h:322:31:   required from 'std::vector<_Tp,_Alloc>::vector(const std::vector<_Tp,_Alloc>&) [with _Tp = std::unique_ptr<Item,std::default_delete<Item> >; _Alloc = std::allocator<std::unique_ptr<Item,std::default_delete<Item> > >]'
/cygdrive/d/code/itemSet.h:4:19:   required from here
/usr/lib/gcc/x86_64-pc-cygwin/5.4.0/include/c++/bits/stl_construct.h:75:7: error: use of deleted function 'std::unique_ptr<_Tp,_Dp>::unique_ptr(const std::unique_ptr<_Tp,_Dp>&) [with _Tp = Item; _Dp = std::default_delete<Item>]'
     { ::new(static_cast<void*>(__p)) _T1(std::forward<_Args>(__args)...); }

任何人都可以解释我的错误,我怎么能解决我的问题？