Cannot pass const(T) to function with ref const(T)

[Andrey]

Mistake. It says about simple argument:
> cannot pass rvalue argument `xxxxx` of type `Word!(wstring, 
> wstring)` to parameter `ref const(Word!(wstring, wstring)) base`

Function:
> void _setPastBases(const ref Data item, const ref UsualWord 
> base)