[1] https://github.com/elliotgoodrich/SSO-23

Correct me if I'm wrong, but isn't this a worst-case scenario? realloc can, iirc, extend in place. Your original pointer is still invalid then, but no copy is needed then.

Unless I'm missing something?

Equally, what happens to the ordering of variables on the stack? Is this new one pushed as the last one? Or is there space kept open?

E.g.:

    var tasks []task
    var other_var int

Of course use cases are limited (variable length buffers/strings, etc) since the lifetime of anything on the stack has to match the lifetime of the stack frame (i.e the calling function), but it's super fast since it's just bumping up the stack pointer.