std::shared_future::operator=

From cppreference.com
shared_future& operator=( const shared_future& other );
(1) (since C++11)
shared_future& operator=( shared_future&& other );
(2) (since C++11)

Assigns the contents of another shared_future.

1) Releases any shared state and assigns the contents of other to *this. After the assignment, this->valid() == other.valid().
2) Releases any shared state and move-assigns the contents of other to *this. After the assignment, other.valid() == false and this->valid() will yield the same value as other.valid() before the assignment.

[edit] Parameters

other - a std::shared_future that will transfer state to *this

[edit] Return value

*this

[edit] Exceptions

1) (none)
2)
noexcept specification:  
noexcept