This program contains an error that goes undetected during runtime ( memory leak ).Your task is to find why that error occurs and write the correct version of program such that no memory leaks occur.

task1.cpp

/*
Task1

There are three classes in this program
1. Demo    : Holds a temporary string buffer inside it
2. Base    : Parent class with a Demo object inside it ( Polymorphic Base of Derived )
3. Derived : Child class that derives from Base and contains a seperate object of Demo as well

This program contains an error that goes undetected during runtime ( memory leak ).Your task is to find that error and write
the correct version of program such that no memory leaks occur.

Prerequisites:
 * Knowledge of C++ classes
 * Knowledge of Virtual Functions
 * Polymorphism

BONUS POINT : There is one design flaw associated with the program. Think it this way. After allocating memory to b1 there is
a cout call that prints "I am task 1". Problem is if an exception occurs in cout then delete statement would never be called
resulting in a memory leak. Can you guys fix it?
 * You must know about exceptions
 * You must know about RAII
*/

// You can see the output here https://wandbox.org/permlink/7A3UE6JdYNK6VJ3X
// Hint : The online editor can help you find errors faster if you fiddle with it :)
#include<iostream>
/// This class holds a string buffer inside it
class Demo{
    static int active_demo_object_count;
    std::string buffer; // Temporary Buffer On most compilers with SBO enabled size is 32bytes
    public:
    Demo(){std::cout<< "Constructor Invoked - Current Active Objects\t "<<++active_demo_object_count<<"\n";}
    ~Demo(){std::cout<< "Destructor Invoked - Current Active Objects\t "<<active_demo_object_count--<<"\n";}
    
};
int Demo::active_demo_object_count=0;

///Polymorphic Base of Derived !!!
struct Base{
    Demo d1;    
};
///Child class of derived
struct Derived:Base{
    Demo d2;
};

int main(){
    // You cannot modify this part
    Base* b1 = new Derived;
    std::cout<<"I am task 1";
    // Something strange happens here. Notice carefully
    delete b1;
    return 0;
}

In 8th line destructor should be virtual

in line no. 32 and 33 should be the virtual functions in the base class.