相关疑难解决方法(0)

使用此代码:

struct A
{
    int i;
    const int b;
};

// The union is to verify that A is a type that can be used in a union.
union U
{
    A a;
    int b;
};

int main()
{
    U a = {1, 1};
    U b = {2, 1};
}

g ++版本4.8.3抱怨错误:

a.cpp:9:4: error: member ‘A U::a’ with copy assignment operator not allowed in union
  A a;
    ^
a.cpp:9:4: note: unrestricted unions only available with -std=c++11 or -std=gnu++11

但是clang 3.5.0编译这段代码没有错误.哪一个是正确的？这是编译器错误吗？ …