Ownership semantics

Smart pointers are all about clarifying ownership over indirectly accessed resources. If we restrict ourselves to the standard facilities, smart or not-so-smart, what we have is the following:

Type	Niche
unique_ptr<T>	Ownership semantics: Single ownership. Notable special member functions: Non-copyable. The destructor is responsible for destroying the pointee.
shared_ptr<T>	Ownership semantics: Shared ownership. Notable special member functions: Copying, assigning, and destroying update a shared use count. The destructor of the last co-owner is responsible for destroying both the pointee and the use count.
T*	Ownership semantics: No ownership is defined in the type system (ownership rules have to be inscribed...