On 30 May 2013 16:57, Nikolay Ivchenkov <mk.ivchenkov@gmail.com> wrote:

regardless of the definition of f (which may be unknown for compiler). There is no legal way to modify reference x.ref after its initialization so that it would refer to a different location. Even if we overwrite the storage of x by construction of a new object of type X at address &x (our f could do such thing), a compiler may assume that x.ref is untouched. The same applies to the original example with optional.

I see, thanks, that's a very good explanation. But there's still the difference that the 3.8/7 would seem to refer to
the storage of A inside the optional (in the original example of yours), and we never had a pointer or a reference
to that storage, but we have a reference inside that storage. Same with this latest example of yours, isn't

explicit destruction and placement-new of x legal, and allowed to modify the reference inside the storage

of x? If we had a pointer/reference to that storage previously, we wouldn't be able to refer to the new
object via those, but in the example we do not have such a pointer/reference.