struct SS {int a; int s;};
int main ()
   vector<SS> v;
   v.push_back(SS{1, 2});
}

可以编译代码而不会出现任何错误。然而，当结构在类中初始化时，我得到了编译错误。有人能解释一下吗？

struct SS {int a = 0; int s = 2;};

错误：

In function ‘int main()’:
error: no matching function for call to ‘SS::SS(<brace-enclosed initializer list>)’
     v.push_back(SS{1, 2});
note: candidates are:
note: constexpr SS::SS()
 struct SS {int a = 0; int s = 2;};