toUTF16 can take a char[], wchar[] or dchar[].

But toUTF16z can only take a char[]. Why?

I'm storing some text as dchar[] internally and have to pass it to WinAPI Unicode functions which expect null-terminated UTF16 strings. But toUTF16z only works with char[] for some reason.

I guess this should do it:

const(wchar)* toUTF16z(in dchar[] s)
{
    return (toUTF16(s) ~ "\000").ptr;
}