std::istream_iterator<T,CharT,Traits,Distance>::~istream_iterator

From cppreference.com
~istream_iterator() = default;
1) Destroys the iterator, including the cached value.

If T is a literal type, then this destructor is a trivial destructor

(since C++11)
(until C++17)

If std::is_trivially_destructible_v<T> is true, then this destructor is a trivial destructor.

(since C++17)