Construct a new std::experimental::shared_ptr object that shares
ownership the supplied std::shared_ptr
instance.
explicit shared_ptr(std::shared_ptr<T> const& p);
If p.use_count()>0, construct a new std::experimental::shared_ptr instance that
shares ownership with p.
Otherwise constructs a new empty
std::experimental::shared_ptr instance.
this->use_count()==p.use_count()
and this->get()==static_cast<T*>(p.get())
for the newly-constructed std::experimental::shared_ptr object. If
p.use_count()>0 before the constructor invocation
then p.use_count()
is increased by 1.
std::bad_alloc if memory cannot be
allocated for any necessary internal structures.
If the std::shared_ptr instance was constructed
from a std::experimental::shared_ptr then no allocation
is necessary.
The std::shared_ptr use count will not
increase if any further copies of the std::experimental::shared_ptr instance are
made.
#include <experimental/atomic>