void main()
{
    const(char)*  cptr  = "foo";  // ok
    const(wchar)* wcptr = "foo"w; // error
}

Error: cannot implicitly convert expression ("foo"w) of
type immutable(wchar)[] to const(wchar)*

By fixing this it should eliminate the need to call std.utf.toUTF16z on string literals passed to WinAPI functions expecting zero-terminated wide strings.

Note that dstrings suffer from the same issue:
const(dchar)* dcptr = "foo"d;  // error

However I'm not sure if there are any C libraries which would take a UTF32 zero-terminated string. It would be consistent to make them all behave the same way though.