Leaving a pointer to it on the stack

[Steven Schveighoffer]

On 8/13/20 4:04 PM, Andre Pany wrote:
> 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)
> 

The garbage collector scans all of the stack as if it were an array of 
pointers. So if you have a pointer to it anywhere on the stack, it won't 
be collected.

However, it only scans threads that the runtime knows about.

-Steve