Error in MinGW gcc 4.9.3 while passing -std=c++11 or -std=c++0x in command prompt

I have installed latest MinGW gcc 4.9.3 compiler on windows 8.

It do not support c++11(I dont know why?).

The below code only supported in c++11 hence throwing error.

#include<bits/stdc++.h>
using namespace std;
int main()
{
set<int> my_set = {12,23,3,4,55};
for(auto i: s)
    cout<<i<<" ";
return 0;
}

I have two questions:

1.Passing -std=c++11 or -std=c++0x is displays hundred of lines of errors. whats is wrong with that(any bug in MinGW?)

2.How do i make compiler support for c++11 for particularly for this compiler ?