带联合的静态unordered_map初始化

Question

以下静态初始值设定项列表M失败，但N成功，当将3 const char *指针的并集添加到init-list时，似乎我不知道如何进行unordered_map初始化。我尝试了。表示无法访问联合字段和联合本身的符号。

#include <iostream>
#include <unordered_map>
#include <iterator>

struct C {
    int j;
    int i;
};

struct D {
    int j;
    char c;
};

struct E {
    const char *a;
    const char *b;
    const char *c;
}e;

struct A {
    const char *s;
    union {
        C c;
        D d;
        E e;
    } u;
};

std::unordered_map<unsigned int, A> m ({
        {1, {"tom",53,'o'}},
        {2, {"ming",40,41}},
        {3, {"peter","a","b","c"}} });

std::unordered_map<unsigned int, A> n ({
        {1, {"tom",53,'o'}},
        {2, {"ming",40,41}} });,

int main(void) {
    for ( const auto& i : m) {
        const auto& j = i.second;
        if (i.first == 1)
            std::cout << "key: " << i.first << " value: " << j.u.d.j << ":" << j.s << ":" << j.u.d.c << std::endl;
        else if (i.first == 2)
            std::cout << "key: " << i.first << " value: " << j.u.c.j << ":" << j.s << ":" << j.u.c.i << std::endl;
        else if (i.first == 3)
            std::cout << "key: " << i.first << " value: " << j.u.e.a << ":" << j.s << ":" << j.u.e.c << std::endl;
    }

    for ( const auto& i : n) {
        const auto& j = i.second;
        if (i.first == 1)
            std::cout << "key: " << i.first << " value: " << j.u.d.j << ":" << j.s << ":" << j.u.d.c << std::endl;
        else if (i.first == 2)
            std::cout << "key: " << i.first << " value: " << j.u.c.j << ":" << j.s << ":" << j.u.c.i << std::endl;
    }

    return 0;
}

错误： map.cpp：41：32：错误：没有匹配的函数可以调用“ std :: unordered_map :: unordered_map（）”