suggestion: R.n (extend R.35,R.36) for shared_ptr<widget>&& parameter

Title might be like:
R.n: Take a shared_ptr<widget>&& parameter to express that caller is expected to transfer "it's" reference count

I'm about to design this into an interface. The background thought is, that there is something like a "primary owner", although ownership is shared technically. shared_ptr is needed for some reason external to the function that takes the argument (in this case: weak_ptr are necessary to cross-reference objects owned by the smart pointers).

The envisioned situation at the callers side is constructing an object and handing it over to the "primary owner". To express that the caller is requested to transfer ownership instead of sharing it, a rvalue reference is used for the parameter. (Of course nothing technically prevents the caller from retaining a copy of the shared_ptr, but the interface expresses that the expectation is otherwise.)