import std.stdio;

void main()
{
    int[] a; a.length = 3;
    int[] b; b.length = 3;
    // both of the following cause same error.
    // Error: var has no effect in expression (c0)
    a[] <<= b[];
    a[] <<= 1;
    // another error message.
    // Error: 'a[]' is not of integral type, it is a int[]
    a[] = a[] << 1;
    a[] = a[] << b[];
}

I don't see why bit shift operation is not arrowed in array operations.