ID management: Do not assume that `NO_MAIN` means `NO_USER_REFCOUNT`

While this is still very fuzzy in current code, this old behavior makes
it close to impossible to efficiently use out-of-main temp data, as it
implies that we'd need to update refcounts everytime we add something
back into BMain (an 'un-refcount' ID usages when removing from BMain).

Now that we have two separate flags/tags for those two different things,
let's not merge them anymore.

Note that this is somewhat on-going process, still needs more checks and
cleanup. Related to T88555.

1 files changed, 4 insertions, 3 deletions

diff --git a/source/blender/blenkernel/intern/lib_query.c b/source/blender/blenkernel/intern/lib_query.c
index 3281783d81a..b748061ef8a 100644
--- a/source/blender/blenkernel/intern/lib_query.c
+++ b/source/blender/blenkernel/intern/lib_query.c
@@ -244,9 +244,10 @@ static void library_foreach_ID_link(Main *bmain,
      * (the node tree), but re-use those generated for the 'owner' ID (the material). */
     if (inherit_data == NULL) {
       data.cb_flag = ID_IS_LINKED(id) ? IDWALK_CB_INDIRECT_USAGE : 0;
-      /* When an ID is not in Main database, it should never refcount IDs it is using.
-       * Exceptions: NodeTrees (yeah!) directly used by Materials. */
-      data.cb_flag_clear = (id->tag & LIB_TAG_NO_MAIN) ? IDWALK_CB_USER | IDWALK_CB_USER_ONE : 0;
+      /* When an ID is defined as not refcounting its ID usages, it should never do it. */
+      data.cb_flag_clear = (id->tag & LIB_TAG_NO_USER_REFCOUNT) ?
+                               IDWALK_CB_USER | IDWALK_CB_USER_ONE :
+                               0;
     }
     else {
       data.cb_flag = inherit_data->cb_flag;