std::array constructor behaves different between compilers [duplicate]

This question already has an answer here:

• c++11 array initialization won't call copy constructor 1 answer

I have the following code where b is list-initialized with another array.

#include <iostream>
#include <array>

int main()
{
    std::array<int, 4> a{1,2,3,4};
    std::array<int, 4> b{a};
    std::cout<<b[3]<<std::endl;
    return 0;
}

I am wondering why this code compiles under one compiler used by wandbox.

But it fails by another compiler used by cpp.sh.