RAII and Stack-unwinding

#include <iostream>
#include <stdexcept>

using namespace std;

class resource
{
public:
  resource(const string & resource_name_)
    : _resource_name(resource_name_)
  {
    cout << "resource::resource()" << endl;

    cout << "acquired resource: "
         << _resource_name << endl;
  }

  ~resource()
  {
    cout << "resource::~resource()" << endl;

    cout << "releasing resource: "
         << _resource_name << endl;
  }
private:
  string _resource_name;
};

class raii_test
{
public:
  raii_test()
    : _rt("resource_1") {};

  void f1()
  {
    resource local_resource("resource_2");

    cout << "raii_test::f1()" <<endl;

    f2();
  }

  void f2()
  {
    cout << "raii_test::f2()" << endl;

    cout << "Throwing" << endl;

    throw runtime_error("Timepass");
  }

  void operator()()
  {
    cout << "In raii_test::operator()" << endl;

    f1();
  }

  ~raii_test()
  {
    cout << "raii_test::~raii_test" << endl;
  }

private:
  resource _rt;
};

int
main()
{
//   try
    {
      raii_test obj;

      obj();
    }
//   catch (...)
//     {
//       throw;
//     }
}

-----

Uncommenting the commented-out code causes RAII-enabled resource deallocation to work correctly. Here are the outputs with commented and uncommented code that show that:

Output with commented-out code:
main()
resource::resource()
acquired resource: resource_1
In raii_test::operator()
raii_test::f1()
resource::resource()
acquired resource: resource_2
raii_test::f2()
Throwing
terminate called after throwing an instance of 'std::runtime_error'
  what():  foo bar baz
Aborted

Output without commented code. Note the correct deallocation/release of acquired resources:
main()
resource::resource()
acquired resource: resource_1
In raii_test::operator()
raii_test::f1()
resource::resource()
acquired resource: resource_2
raii_test::f2()
Throwing
resource::~resource()
releasing resource: resource_2
raii_test::~raii_test
resource::~resource()
releasing resource: resource_1
terminate called after throwing an instance of 'std::runtime_error'
  what():  foo bar baz
Aborted