C++ : Cloning Go Defer keyword functionality

defer.cpp

// Check playground in: https://www.mycompiler.io/view/7pXriajivQt

#include <iostream>
#include <memory>
#include <functional>

//--- CONCAT ----------------------------------------------
#define detail_CONCAT(a, b) a##b
#define CONCAT(a, b) detail_CONCAT(a, b)
//---------------------------------------------------------

//--- DEFER -----------------------------------------------
#define detail_DEFER0 std::unique_ptr<void, std::function<void (void *)>>
#define detail_DEFER1 []() { static int a=0; return &a; }
#define DEFER(fn) auto CONCAT(defer_,__LINE__) = detail_DEFER0( detail_DEFER1(), [&](void *) { fn; } )
//---------------------------------------------------------

int main()
{ // In: Scope 0  
    
    { // In: Scope 1
        std::vector<std::string> names = { "Lisa", "John" };
        DEFER( std::cout << "Bye bye, have a good day " << names[0] << " and you too "<< names[1] << "!\n" );   
        std::cout << "Hello mate!\n";
        std::cout << "Hey, nice to see you all!\n";
        std::cout << "...\n" << "...\n" << "...\n";
    } // Out: Scope 1
    
    std::cout << "Same to you!" << std::endl;
    return 0;
    
} // Out: Scope 0