Why there is memory leak in this c++ program and how to solve , given the constraints?

This is Minimal Working Example, for the problem I am facingin in my real code.

#include <iostream>

namespace Test1 {
static const std::string MSG1="Something really big message";
}

struct Person{
  std::string name;
};

int main() {
    auto p = (Person*)malloc(sizeof(Person));
    p = new(p)Person();
    p->name=Test1::MSG1;

    std::cout << "name: "<< p->name << std::endl;
    
    free(p);
    
    std::cout << "done" << std::endl;

    return 0;
}

When I compile it and run it via valgrind it gives me error: definitely lost: 31 bytes in 1 blocks

Constraints

1. I am bind to use malloc in the example above, as in my real code I use a C library in my C++ project, which uses this malloc internally. So can’t get away from malloc usage, as I don’t do it explicitly anywhere in my code.
2. I need to reassign std::string name of Person again and again in my code.

>Solution :

You must manually call the destructor before free(p);:

p->~Person();

Or std::destroy_at(p), which is the same thing.