#include <cstdlib>
#include <set>

int main()
{
#ifdef __GNUC__
  std::set<int, std::less<int> > s1;
  std::set<int, std::greater<int> > s2;
  std::set<int, std::less<int> >::iterator it = s2.begin();
#endif
  return EXIT_SUCCESS;
}

In function 'int main()':
Line 9: error: conversion from '__gnu_debug::_Safe_iterator<std::_Rb_tree_const_iterator<int>, __gnu_debug_def::set<int, std::greater<int>, std::allocator<int> > >' to non-scalar type '__gnu_debug::_Safe_iterator<std::_Rb_tree_const_iterator<int>, __gnu_debug_def::set<int, std::less<int>, std::allocator<int> > >' requested
compilation terminated due to -Wfatal-errors.