Use std::mem_fn instead of the deprecated/removed std::mem_fun
std::mem_fun was deprecated in C++11 and removed from the standard in C++17.
From https://en.cppreference.com/w/cpp/utility/functional/mem_fun:
This function and the related types were deprecated in C++11 and removed in C++17 in favor of the more general std::mem_fn and std::bind, both of which create callable adapter-compatible function objects from member functions.
BUG: 439780 NO_CHANGELOG
Edited by Jan Paul Batrina