About Immutable struct members and arrays.

[Jack Applegame via Digitalmars-d-learn]

import std.algorithm;

struct Bar {
    const int a;
    int b;
}
void main() {
    Bar[1] arr;
    Bar bar = Bar(1, 2);
    bar[0].b = 4;
    move(bar, arr[0]);       // ok
    arr[1] = bar;            // fail, why?
    move(Bar(1, 2), arr[0]); // fail, why source parameter isn't 
auto ref?
}