Constructs a new std::experimental::shared_ptr object that shares
ownership with an existing object and has the same pointer value.
shared_ptr(shared_ptr const& other) noexcept
Constructs a new std::experimental::shared_ptr object with
the same pointer value as other
which shares ownership with other.
If other->use_count()!=0, increases the value of other->use_count()
by 1.
p.use_count()==other.use_count()
and !p.owner_before(other) and !other.owner_before(p)
and p.get()==other.get()
Nothing.
#include <experimental/atomic>