C++ initializer lists for arbitrary length vectors

I will be working with vectors of arbitrary length, but fixed size at compile time. I was trying to initialize them from an initializer list as follows. I noticed there was a similar discussion here: #954 (closed) but it seemed to have been forgotten.

// This works
Eigen::Matrix<double, 3, 1> a({1., 2., 3.});
std::cout << a << "\n";


// This looks like it should work but does not work
Eigen::Matrix<double, 6, 1> b({1., 2., 3., 4., 5., 6.});
std::cout << b << "\n";

Are there plans to extend Eigen to allow for initialization of arbitrary length vectors from initializer lists? It seems weird to me that 4 is the magic number after which initializer lists stop working. Thanks!