https://godbolt.org/z/oYsa7W

everytime_there_are_weirdos.cpp

// Type your code here, or load an example.
#include <string>
#include <map>

using namespace std;

// https://youtu.be/hEx5DNLWGgA?t=4261

void f(void) {

    map<int, string> m = {{1, "one"}, {2, "two"}}, m2;

    m.insert(m2.begin(), {3, "three"}); // should be error
    m.insert(m.begin(), {3, "three"}); // ok, m.begin() points to m
    m.insert(m.begin(), m.end());  // 2 ERRORS: (1) params point to m, and (2) m is modifiable by m.insert
    m.insert(m2.begin(), m.end());  // ERROR param1 points to m2, but param2 points to m
    m.insert(m2.begin(), m2.end());  // OK, params point to m2, m2 not modifiable by m.insert
}