Leaving a pointer to it on the stack

[Andre Pany via Digitalmars-d-learn]

Hi,

in the specification 
https://dlang.org/spec/interfaceToC.html#storage_allocation there 
is this paragraph:
"Leaving a pointer to it on the stack (as a parameter or 
automatic variable), as the garbage collector will scan the 
stack."

I have some trouble to understand what does this mean. Given this 
example:

```
import std;

void main()
{
        int* i;
        sample(&i);
        writeln(*i);
}

extern(C) export void sample(int** i)
{
        *i = new int();
        **i = 42;
}
```

Int variable is created on the heap. How do I leave a pointer on 
the stack?
(In the real coding, sample function will be called from Delphi)

Kind regards
André