boost :: flat_set的迭代器无法合并

Question

I'm trying to use boost::flat_set for small sets of iterators which I require to be unique. The code does not compile as there is an ambiguous call to make_reverse_iterator , but I'm not sure how it is happening. I've tried to reduce the problem to a MWE:

#include <boost/container/flat_set.hpp>
#include <set>
#include <iostream>

using Set = std::set<int>;
using SetIt = Set::iterator;

struct Comparator {
    bool operator()(SetIt lhs, SetIt rhs) const {
        return &(*lhs) < &(*rhs);
    }
};


int main() {
    std::set<int> x;
    boost::container::flat_set<Set::iterator, Comparator> a;
    boost::container::flat_set<Set::iterator, Comparator> b;

    a.insert(x.insert(1).first);
    a.insert(x.insert(2).first);
    a.insert(x.insert(3).first);
    a.insert(x.insert(4).first);
    a.insert(x.insert(5).first);

    b.insert(x.insert(3).first);
    b.insert(x.insert(4).first);
    b.insert(x.insert(5).first);
    b.insert(x.insert(6).first);
    b.insert(x.insert(7).first);

    a.merge(b);

    for (auto v : a)
        std::cout << *v << '\n';
    return 0;
}

Answer 1

This problem is apparently fixed in Boost 1.67 .

I reproduced the error on fixed in Boost 1.66 .