Awesome talk. However, is emplace_back of the vector into itself guaranteed to work? I think it might only be working because of an implementation which doesn't increment its internal size until after construction, rather than incrementing and rolling back if an exception is thrown (which I don't believe is forbidden by the standard).
Similarly, an emplace into the middle of the vector with itself seems like it could never work.
I can see how push_back/insert would work, because the copies would be made at the call site, before the vector is modified.
Just seems a little dangerous, unless I'm missing something.