Missing API to interact with the underlying pointer types

[Mingxin Wang]

Sometimes it is useful to invoke a dispatch on the underlying pointer types without dereferencing them. For example, when refactoring the following code with proxy:

struct IMyAbstraction { ...; };

std::shared_ptr<IMyAbstraction> p = ...;
std::weak_ptr<IMyAbstraction> weak{p};
...
auto locked = weak.lock();
if (static_cast<bool>(locked)) {
  ...
}

It is currently infeasible to create a std::weak_ptr from a proxy, even if the underlying pointer is std::shared_ptr, because there is currently no API to touch the underlying pointer via a proxy.