std::forward_list<T,Allocator>:: ~forward_list

From cppreference.com

~forward_list ( ) ;
(since C++11)

A destructor . Destructs the forward_list . The destructors of the elements are called and the used storage is deallocated. Note, that if the elements are pointers, the pointed-to objects are not destroyed.

Complexity

Linear in the size of the forward_list .