According to this answer, an iterator must be implicitly convertible to const_iterator. Since that is true, as we can see happening in insert_or_assign(), then why in C++17 was a new signature added to std::map::erase()?
In C++11, we have iterator erase( const_iterator pos );
In C++17, we now have iterator erase( iterator pos );
Wasn't the C++11 signature good enough to receive iterator and const_iterator?
There's a potential ambiguity with erase(const key_type& key) when you pass an iterator. Consider the case where the key_type is something like std::any.