LibOverride: Fix (unreported) crashes in some cases, preserve active object on Clear, general cleanup.

Inconsistencies in update/tagging code between different code doing the
same 'Clear. liboverride operation lead to crashes in some cases.

Unify deg tagging and WM notifiers accross the three editor-level
codepaths performing the common Make/Reset/Clear operations.

Preserve if possible the active object accross Clear operation.

Several cleanup/rename/re-arangement of code to make it more consistent.

2 files changed, 54 insertions, 23 deletions

diff --git a/source/blender/editors/interface/interface_ops.c b/source/blender/editors/interface/interface_ops.c
index e170cb46925..3a5ba9acaac 100644
--- a/source/blender/editors/interface/interface_ops.c
+++ b/source/blender/editors/interface/interface_ops.c
@@ -820,19 +820,26 @@ static int override_idtemplate_make_exec(bContext *C, wmOperator *UNUSED(op))
     return OPERATOR_CANCELLED;
   }
 
-  if (ID_IS_OVERRIDE_LIBRARY_REAL(owner_id)) {
-    PointerRNA idptr;
-    /* `idptr` is re-assigned to owner property to ensure proper updates etc. Here we also use it
-     * to ensure remapping of the owner property from the linked data to the newly created
-     * liboverride (note that in theory this remapping has already been done by code above), but
-     * only in case owner ID was already an existing liboverride.
-     *
-     * Otherwise, owner ID will also have been overridden, and remapped already to use it's
-     * override of the data too. */
+  PointerRNA idptr;
+  /* `idptr` is re-assigned to owner property to ensure proper updates etc. Here we also use it
+   * to ensure remapping of the owner property from the linked data to the newly created
+   * liboverride (note that in theory this remapping has already been done by code above), but
+   * only in case owner ID was already local ID (override or pure local data).
+   *
+   * Otherwise, owner ID will also have been overridden, and remapped already to use it's
+   * override of the data too. */
+  if (!ID_IS_LINKED(owner_id)) {
     RNA_id_pointer_create(id_override, &idptr);
     RNA_property_pointer_set(&owner_ptr, prop, idptr, NULL);
-    RNA_property_update(C, &owner_ptr, prop);
   }
+  RNA_property_update(C, &owner_ptr, prop);
+
+  /* 'Security' extra tagging, since this process may also affect the owner ID and not only the
+   * used ID, relying on the property update code only is not always enough. */
+  DEG_id_tag_update(&CTX_data_scene(C)->id, ID_RECALC_BASE_FLAGS | ID_RECALC_COPY_ON_WRITE);
+  WM_event_add_notifier(C, NC_WINDOW, NULL);
+  WM_event_add_notifier(C, NC_WM | ND_LIB_OVERRIDE_CHANGED, NULL);
+  WM_event_add_notifier(C, NC_SPACE | ND_SPACE_VIEW3D, NULL);
 
   return OPERATOR_FINISHED;
 }
@@ -881,6 +888,9 @@ static int override_idtemplate_reset_exec(bContext *C, wmOperator *UNUSED(op))
   RNA_property_pointer_set(&owner_ptr, prop, idptr, NULL);
   RNA_property_update(C, &owner_ptr, prop);
 
+  /* No need for 'security' extra tagging here, since this process will never affect the owner ID.
+   */
+
   return OPERATOR_FINISHED;
 }
 
@@ -919,24 +929,45 @@ static int override_idtemplate_clear_exec(bContext *C, wmOperator *UNUSED(op))
   }
 
   Main *bmain = CTX_data_main(C);
+  ViewLayer *view_layer = CTX_data_view_layer(C);
+  Scene *scene = CTX_data_scene(C);
   ID *id_new = id;
+
   if (BKE_lib_override_library_is_hierarchy_leaf(bmain, id)) {
     id_new = id->override_library->reference;
+    bool do_remap_active = false;
+    if (OBACT(view_layer) == (Object *)id) {
+      BLI_assert(GS(id->name) == ID_OB);
+      BLI_assert(GS(id_new->name) == ID_OB);
+      do_remap_active = true;
+    }
     BKE_libblock_remap(bmain, id, id_new, ID_REMAP_SKIP_INDIRECT_USAGE);
+    if (do_remap_active) {
+      Object *ref_object = (Object *)id_new;
+      Base *basact = BKE_view_layer_base_find(view_layer, ref_object);
+      if (basact != NULL) {
+        view_layer->basact = basact;
+      }
+      DEG_id_tag_update(&scene->id, ID_RECALC_SELECT);
+    }
     BKE_id_delete(bmain, id);
   }
   else {
     BKE_lib_override_library_id_reset(bmain, id, true);
   }
 
-  PointerRNA idptr;
-  /* `idptr` is re-assigned to owner property to ensure proper updates etc. Here we also use it to
-   * ensure remapping of the owner property from the linked data to the newly created liboverride
-   * (note that in theory this remapping has already been done by code above). */
-  RNA_id_pointer_create(id_new, &idptr);
-  RNA_property_pointer_set(&owner_ptr, prop, idptr, NULL);
+  /* Here the affected ID may remain the same, or be replaced by its linked reference. In either
+   * case, the owner ID remains unchanged, and remapping is already handled by internal code, so
+   * calling `RNA_property_update` on it is enough to ensure proper notifiers are sent. */
   RNA_property_update(C, &owner_ptr, prop);
 
+  /* 'Security' extra tagging, since this process may also affect the owner ID and not only the
+   * used ID, relying on the property update code only is not always enough. */
+  DEG_id_tag_update(&scene->id, ID_RECALC_BASE_FLAGS | ID_RECALC_COPY_ON_WRITE);
+  WM_event_add_notifier(C, NC_WINDOW, NULL);
+  WM_event_add_notifier(C, NC_WM | ND_LIB_OVERRIDE_CHANGED, NULL);
+  WM_event_add_notifier(C, NC_SPACE | ND_SPACE_VIEW3D, NULL);
+
   return OPERATOR_FINISHED;
 }
 
diff --git a/source/blender/editors/interface/interface_templates.c b/source/blender/editors/interface/interface_templates.c
index 95952b6e8c8..7d27af7220e 100644
--- a/source/blender/editors/interface/interface_templates.c
+++ b/source/blender/editors/interface/interface_templates.c
@@ -885,14 +885,14 @@ static void template_id_liboverride_hierarchy_make(bContext *C,
       C, bmain, owner_id, id, r_undo_push_label);
 
   if (id_override != NULL) {
-    /* Given `idptr` is re-assigned to owner property by caller to ensure proper updates etc. Here
-     * we also use it to ensure remapping of the owner property from the linked data to the newly
-     * created liboverride (note that in theory this remapping has already been done by code
-     * above), but only in case owner ID was already an existing liboverride.
+    /* `idptr` is re-assigned to owner property to ensure proper updates etc. Here we also use it
+     * to ensure remapping of the owner property from the linked data to the newly created
+     * liboverride (note that in theory this remapping has already been done by code above), but
+     * only in case owner ID was already local ID (override or pure local data).
      *
-     * Otherwise, owner ID will also have been overridden, and remapped already to use
-     * it's override of the data too. */
-    if (ID_IS_OVERRIDE_LIBRARY_REAL(owner_id)) {
+     * Otherwise, owner ID will also have been overridden, and remapped already to use it's
+     * override of the data too. */
+    if (!ID_IS_LINKED(owner_id)) {
       RNA_id_pointer_create(id_override, idptr);
     }
   }