ulong[] result = iota(1UL, 10UL).array;
Error: static assert "Argument types in (ulong) are not all convertible to size_t: (ulong)" C:\D\dmd2\src\phobos\std\array.d 516
And while I'm here why do arrays not implicitly cast? ulong is happy to accept uint values but ulong[] will not accept uint[].