“Appends a new element to the end of the container. The element is
constructed in-place,i.e. no copy or move operations are performed.
The constructor of the element is called with exactly the same
arguments that are supplied to the function.”

以下示例：

#include <vector>
struct A
{
    A(int){}
    A(A const&) = delete;
};

int main()
{
    std::vector<A> vec;
    vec.emplace_back(1);

    return 0;
}

在线vec.emplace_back(1); Visual Studio 2013 / GCC报告：

error C2280: ‘A::A(const A &)’ : attempting to reference a deleted function

error: use of deleted function ‘A::A(const A&)’

错误是否正确？你能解释一下为什么吗