std::codecvt::out() returns a no-op in marginal situations

[Paolo Carlini]

Sam Varshavchik wrote:
> So, if out() returns with:
>
> 1) from_next < from_end, and
>
> 2) to_next < to_end
>
> then can I assume that out() wants a larger output buffer?
In short, I think so. I cannot imagine how things could be different:
one internal element is enough for a meaningful conversion, and you know
you have got it. And you have a partial return value. The only possible
explanation is that the output buffer is too small.

Paolo.