Forked GC explained

[Steven Schveighoffer]

On 9/5/22 7:12 AM, frame wrote:
> And what if the programmer has no actual reference but wrongly forced a 
> `free()` through a pointer cast?

https://dlang.org/spec/garbage.html#pointers_and_gc

* Do not store pointers into non-pointer variables using casts and other 
tricks.
```d
void* p;
...
int x = cast(int)p;   // error: undefined behavior
```
The garbage collector does not scan non-pointer fields for GC pointers.

Note that this does not require the forked GC to cause this problem.

-Steve