Return a weak_ptr holding a weak reference (with only const access) to this managed object if this object is currently managed by shared_ptr, and return an expired weak_ptr otherwise. If multiple groups of shared_ptrs are managing this object, the returned weak_ptr will hold a weak reference to the group that first managed this object.
Declared in <bslstl_sharedptr.h>
bsl::weak_ptr<ELEMENT_TYPE const>
weak_from_this() const noexcept;