c++ - 复制构造函数不是继承的

Question

我有以下代码:

class C {
public:
    C(int) {}
    C(const C&) {}
    C() {}
};  

class D : public C { 
public:
    using C::C;
};  

int main() {
    C c;
    D d_from_c(c); // does not compile, copy ctor is not inherited
    D d_from_int(1); // compiles, C(int) is inherited
}   

派生类应该继承除默认 ctor 之外的所有 base ctors(解释为 here )。但是为什么 copy ctor 也没有被继承呢？相关问题的论点在这里是 Not Acceptable 。

代码使用 g++ 4.8.1 编译。

Answer 1

因为标准是这么说的。 [class.inhctor]/p3，强调我的:

For each non-template constructor in the candidate set of inherited constructors other than a constructor having no parameters or a copy/move constructor having a single parameter, a constructor is implicitly declared with the same constructor characteristics unless there is a user-declared constructor with the same signature in the complete class where the using-declaration appears or the constructor would be a default, copy, or move constructor for that class.