[SOLVED] Question about (broken) handling refcounter

Archive Blender Development
1

I’ve discovered several cases of broken ref counter (in particular, just ungrouping nodes or creating new material).

It seems like refcounters should be handled in BKE_id_copy_ex by this code:

  /* Update ID refcount, remap pointers to self in new ID. */
  struct IDCopyLibManagementData data = {
      .id_src = id,
      .id_dst = *r_newid,
      .flag = flag,
  };
  BKE_library_foreach_ID_link(bmain, *r_newid, id_copy_libmanagement_cb, &data, IDWALK_NOP);

But to make it work, the id_copy_libmanagement_cb should be called with IDWALK_CB_USER set in cb_flag:

/* Increase used IDs refcount if needed and required. */
  if ((data->flag & LIB_ID_CREATE_NO_USER_REFCOUNT) == 0 && (cb_flag & IDWALK_CB_USER)) {
    id_us_plus(id);
  }

And it’s is not the case in BKE_id_copy. And it’s never the case.

Do I miss something?

2

Hi, for the records, @mont29 is the developer more familiar with this area.

My suggestion here would be to first report as a bug, so it is easier for another developer to confirm and have a reliable .blend and steps to reproduce.

Once confirmed that this is not working as expected, Bastien (or someone else) can review your patches to fix that.

3

I’ve recently commited a set of autotests that reveal a bunch of bugs of this matter.

Now I’m exploring the code in hope that I can fix it myself.

This particular line might be a bug that’s actually compensated by another bug somewhere else.

4

Well, what I missed is that BKE_library_foreach_ID_link do not use the flag directly, but uses a PILE of scary macros to actually call the callback.
The macros call it with IDWALK_CB_USER.

But somehow not for material copypaste or new/clone.