相关疑难解决方法(0)

以下代码不会在gcc 4.8.2上编译.问题是此代码将尝试复制构造,std::pair<int, A>这是由于struct A缺少复制和移动构造函数而无法发生的.

gcc在这里失败了还是我错过了什么？

#include <map>
struct A
{
  int bla;
  A(int blub):bla(blub){}
  A(A&&) = delete;
  A(const A&) = delete;
  A& operator=(A&&) = delete;
  A& operator=(const A&) = delete;
};
int main()
{
  std::map<int, A> map;
  map.emplace(1, 2); // doesn't work
  map.emplace(std::piecewise_construct,
          std::forward_as_tuple(1),
          std::forward_as_tuple(2)
  ); // works like a charm
  return 0;
}