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#include <iostream>
#include <vector>
#include <list>
#include <type_traits>
#include <iterator>
 
template<typename Iterator, typename U = typename std::vector<typename std::iterator_traits<Iterator>::value_type>::iterator, typename = void>
auto f(Iterator beg, U end)
-> typename std::enable_if<!std::is_same<Iterator, U>::value, void>::type
{
    for(auto it = beg; it != end; it = std::next(it))
    {
        std::cout << *it << " iterator!" << std::endl;
    }
}
/*
template<typename Iterator, typename U = typename std::vector<typename std::iterator_traits<Iterator>::value_type>::iterator>
auto f(Iterator beg, U end)
-> typename std::enable_if<std::is_same<Iterator, U>::value, void>::type
{
    for(auto it = beg; it != end; it = std::next(it))
    {
        std::cout << *it << " vector!" << std::endl;
    }
}*/
 
int main()
{
    std::list<int> x = {1,2,3};
    std::cout << "List" << std::endl;
    f(x.begin(), x.end());
 
    std::cout << "Vector" << std::endl;
    std::vector<int> v = {1,2,3};
    f(v.begin(), v.end());
}

prog.cpp: In function ‘int main()’:
prog.cpp:31:25: error: no matching function for call to ‘f(std::__cxx11::list<int>::iterator, std::__cxx11::list<int>::iterator)’
     f(x.begin(), x.end());
                         ^
prog.cpp:8:6: note: candidate: template<class Iterator, class U, class> typename std::enable_if<(! std::is_same<Iterator, U>::value), void>::type f(Iterator, U)
 auto f(Iterator beg, U end)
      ^
prog.cpp:8:6: note:   template argument deduction/substitution failed:
prog.cpp: In substitution of ‘template<class Iterator, class U, class> typename std::enable_if<(! std::is_same<Iterator, U>::value), void>::type f(Iterator, U) [with Iterator = std::_List_iterator<int>; U = std::_List_iterator<int>; <template-parameter-1-3> = void]’:
prog.cpp:31:25:   required from here
prog.cpp:8:6: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’
prog.cpp:35:25: error: no matching function for call to ‘f(std::vector<int>::iterator, std::vector<int>::iterator)’
     f(v.begin(), v.end());
                         ^
prog.cpp:8:6: note: candidate: template<class Iterator, class U, class> typename std::enable_if<(! std::is_same<Iterator, U>::value), void>::type f(Iterator, U)
 auto f(Iterator beg, U end)
      ^
prog.cpp:8:6: note:   template argument deduction/substitution failed:
prog.cpp: In substitution of ‘template<class Iterator, class U, class> typename std::enable_if<(! std::is_same<Iterator, U>::value), void>::type f(Iterator, U) [with Iterator = __gnu_cxx::__normal_iterator<int*, std::vector<int> >; U = __gnu_cxx::__normal_iterator<int*, std::vector<int> >; <template-parameter-1-3> = void]’:
prog.cpp:35:25:   required from here
prog.cpp:8:6: error: no type named ‘type’ in ‘struct std::enable_if<false, void>’

Standard output is empty