Fix T81267: bad handling of usercount for actions duplicated with some animdata.

Those actions are full proper IDs and should therefore not be affected
by flags used to duplicate 'owner' ID own data.

1 files changed, 15 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/anim_data.c b/source/blender/blenkernel/intern/anim_data.c
index fdc23ac50af..c26fc6578f1 100644
--- a/source/blender/blenkernel/intern/anim_data.c
+++ b/source/blender/blenkernel/intern/anim_data.c
@@ -357,10 +357,23 @@ AnimData *BKE_animdata_copy(Main *bmain, AnimData *adt, const int flag)
 
   /* make a copy of action - at worst, user has to delete copies... */
   if (do_action) {
+    /* Recursive copy of 'real' IDs is a bit hairy. Even if do not want to deal with usercount
+     *  when copying ID's data itself, we still need to do so with sub-IDs, since those will not be
+     * handled by later 'update usercounts of used IDs' code as used e.g. at end of
+     * BKE_id_copy_ex().
+     * So in case we do copy the ID and its sub-IDs in bmain, silence the 'no usercount' flag for
+     * the sub-IDs copying.
+     * Note: This is a bit weak, as usually when it comes to recursive ID copy. Should work for
+     * now, but we may have to revisit this at some point and add a proper extra flag to deal with
+     * that situation. Or refactor completely the way we handle such recursion, by flattening it
+     * e.g. */
+    const int id_copy_flag = (flag & LIB_ID_CREATE_NO_MAIN) == 0 ?
+                                 flag & ~LIB_ID_CREATE_NO_USER_REFCOUNT :
+                                 flag;
     BLI_assert(bmain != NULL);
     BLI_assert(dadt->action == NULL || dadt->action != dadt->tmpact);
-    BKE_id_copy_ex(bmain, (ID *)dadt->action, (ID **)&dadt->action, flag);
-    BKE_id_copy_ex(bmain, (ID *)dadt->tmpact, (ID **)&dadt->tmpact, flag);
+    BKE_id_copy_ex(bmain, (ID *)dadt->action, (ID **)&dadt->action, id_copy_flag);
+    BKE_id_copy_ex(bmain, (ID *)dadt->tmpact, (ID **)&dadt->tmpact, id_copy_flag);
   }
   else if (do_id_user) {
     id_us_plus((ID *)dadt->action);