This method is only available on newer versions.
The first available version (v2_6_3) is shown here.
to_a()
public
Returns an array containing the items in the range.
(1..7).to_a#=> [1, 2, 3, 4, 5, 6, 7](1..).to_a#=> RangeError: cannot convert endless range to an array
static VALUE
range_to_a(VALUE range)
{
if (NIL_P(RANGE_END(range))) {
rb_raise(rb_eRangeError, "cannot convert endless range to an array");
}
return rb_call_super(0, 0);
}