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#include <vector>
 
template <typename TopContainer, typename TopElement, typename BottomContainer>
void genericFoo(const TopContainer& topList, BottomContainer TopElement::* bottomList) 
{
    for (auto it = topList.begin(); it != topList.end(); ++it) {
        // ...
        const BottomContainer& list2 = (*it).*bottomList;
        for (auto it2 = list2.begin(); it2 != list2.end(); ++it2) {
            // do some stuff
        }
    }
}
 
struct listA {
    std::vector<char> listOfApples;    
};
 
struct listB {
    std::vector<int> listOfToys;
};
 
std::vector< std::vector<listA> > listOfItems1;
std::vector< std::vector<listB> > listOfItems2;
 
 
int main()
{
    std::vector<int> listB::*pList = &listB::listOfToys;
    genericFoo(listOfItems2, pList);
    return 0;
}

prog.cpp: In function 'void genericFoo(const TopContainer&, BottomContainer TopElement::*) [with TopContainer = std::vector<std::vector<listB> >, TopElement = listB, BottomContainer = std::vector<int>]':
prog.cpp:30:35:   instantiated from here
prog.cpp:8:47: error: pointer to member type 'std::vector<int>' incompatible with object type 'std::vector<listB>'

Standard output is empty