Demonstrates that local variables in C++ are not destroyed before the return expression is evaluated.

local-variable-lifetime.cc

// Output:                                                                                                                                                                                                            
//                                                                                                                                                                                                                    
//   creating A                                                                                                                                                                                                       
//   using A where A.s = 'valid test value'                                                                                                                                                                           
//   destroying A where A.s = 'valid test value'                                                                                                                                                                      
//   valid test value                                                                                                                                                                                                 

#include <iostream>

struct A {
  std::string s;

  A () {
    std::cerr << "creating A" << std::endl;
  }

  ~A() {
    std::cerr << "destroying A where A.s = '" << s << "'" << std::endl;
    s = "removed";
  }
};

std::string use(A const* a) {
  std::cerr << "using A where A.s = '" << a->s << "'" << std::endl;
  return a->s;
}

std::string f() {
  A a;
  a.s = "valid test value";
  return use(&a);
}

int main() {
  std::cout << f() << std::endl;
}