// { dg-do run { target c++17 xfail *-*-* } }
// { dg-require-debug-mode "" }

#include <unordered_map>
#include <algorithm>
#include <testsuite_hooks.h>

using test_type = std::unordered_multimap<int, int>;

void
test01()
{
  test_type c0
    {
     { 1, 1 }, { 1, 1 }, { 2, 2 },
     { 2, 2 }, { 3, 3 }, { 3, 3 }
    };
  std::unordered_map<int, int> c1{ { 1, 1 }, { 2, 2 }, { 3, 3 } };

  auto it = c1.find(2);
  VERIFY( it->second == 2 );

  c0.merge(c1);

  VERIFY( it != c1.end() ); // Invalid iterator.
}

int
main()
{
  test01();
}