Is this expected and good?
void main() {
     int[] array = [1, 2];
     foreach (ref const(int) x; array) {} // OK
     foreach (ref immutable(int) x; array) {} // error
}
DMD 2.060alpha:
temp.d(4): Error: argument type mismatch, int to ref 
immutable(int)
Thank you,
bye,
bearophile