When does an object get into the heap in Go?

In Go, an object is allocated on the heap if its lifetime exceeds the function in which it was created and it needs to be accessible after exiting that function. The Go compiler analyzes where the object is used, and if it sees that the object is needed outside the current call stack, it allocates it on the heap.

For example, if a function returns a pointer to a local variable, that variable will be placed on the heap to avoid losing data after the function exits:

func create() *int {
    x := 42
    return &x // x will be allocated on the heap
}

func main() {
    p := create()
    fmt.Println(*p) // 42
}

If the object is only used within the function and does not go beyond its scope, it will be allocated on the stack for faster performance.