On Thu, Jul 24, 2008 at 4:58 PM, Mathias Gaunard <mathias.gaunard@ens-lyon.org> wrote: <snip>
T::T(T&& o) could make 'o' empty, but there could be no other way to make 'o' empty otherwise.
I think that the biggest problem is that, if T is movable, you cannot statically guarantee that T is never accessed in an empty state, so the never empty guarantee is not as useful.
(I personally wonder if it wouldn't have been better to not call destructors on moved objects)
Again, in general, the type system does not let the compiler know statically if an object has been moved, so you would need an extra bolean flag for each movable type instance to know if that instance has been moved or not. This could be an unacceptable size and performance cost in some cases. -- gpd