I'm trying to do something like this:
type
ThreadID* = distinct uint8
Msg*[T] = object
sender*: ThreadID
receiver*: ThreadID
previous: pointer#ptr[Msg[any]]
content*: T
let space = alloc0(sizeof(Msg[int]))
let m = cast[ptr[Msg[int]]](space)
#let p:ptr[Msg[any]] = m.previous
I would like to define "previous" as something meaning ptr[Msg[any]], so that a
ptr to any concrete Msg[?] can be assigned to it. I'm sure this has been asked
before, but no mater how I phrase it, nothing came up in the search.
The "ugly workaround" is to cast the pointer to some concrete version of Msg,
for example Msg[int], and access the "non generic fields", but not content.
OTOH, I'm not even sure if this is safe, or if the compiler could possibly
choose a different "byte offset" for the "non generic fields", based on T.
