LibOverride: Rename 'delete hierarchy' to 'clear hierarchy', add 'clear single' operations.

'Delete' was a confusing name, even though it would delete the overrides
it would replace them by linked data.

Adding the 'single' version of that operation made it even more
confusing, since often it has to keep the override ID for sakes of
hierarchy, and just reset it and turn it back into a non-editable system
override.

Ref: {T95707}.

5 files changed, 208 insertions, 49 deletions

diff --git a/source/blender/blenkernel/BKE_lib_override.h b/source/blender/blenkernel/BKE_lib_override.h
index daa94031489..2447208b49d 100644
--- a/source/blender/blenkernel/BKE_lib_override.h
+++ b/source/blender/blenkernel/BKE_lib_override.h
@@ -70,6 +70,14 @@ bool BKE_lib_override_library_is_user_edited(struct ID *id);
 bool BKE_lib_override_library_is_system_defined(struct Main *bmain, struct ID *id);
 
 /**
+ * Check if given ID is a leaf in its liboverride hierarchy (i.e. if it does not use any other
+ * override ID).
+ *
+ * NOTE: Embedded IDs of override IDs are not considered as leaves.
+ */
+bool BKE_lib_override_library_is_hierarchy_leaf(struct Main *bmain, struct ID *id);
+
+/**
  * Create an overridden local copy of linked reference.
  *
  * \note This function is very basic, low-level. It does not consider any hierarchical dependency,
@@ -374,12 +382,22 @@ bool BKE_lib_override_library_main_operations_create(struct Main *bmain, bool fo
 
 /**
  * Reset all overrides in given \a id_root, while preserving ID relations.
+ *
+ * \param do_reset_system_override If \a true, reset the given ID as a system override one (i.e.
+ * non-editable).
  */
-void BKE_lib_override_library_id_reset(struct Main *bmain, struct ID *id_root);
+void BKE_lib_override_library_id_reset(struct Main *bmain,
+                                       struct ID *id_root,
+                                       bool do_reset_system_override);
 /**
  * Reset all overrides in given \a id_root and its dependencies, while preserving ID relations.
+ *
+ * \param do_reset_system_override If \a true, reset the given ID and all of its descendants in the
+ * override hierarchy as system override ones (i.e. non-editable).
  */
-void BKE_lib_override_library_id_hierarchy_reset(struct Main *bmain, struct ID *id_root);
+void BKE_lib_override_library_id_hierarchy_reset(struct Main *bmain,
+                                                 struct ID *id_root,
+                                                 bool do_reset_system_override);
 
 /**
  * Set or clear given tag in all operations in that override property data.
diff --git a/source/blender/blenkernel/intern/lib_override.c b/source/blender/blenkernel/intern/lib_override.c
index edb23f51308..eb6d9fe358e 100644
--- a/source/blender/blenkernel/intern/lib_override.c
+++ b/source/blender/blenkernel/intern/lib_override.c
@@ -291,6 +291,32 @@ bool BKE_lib_override_library_is_system_defined(Main *bmain, ID *id)
   return false;
 }
 
+static int foreachid_is_hierarchy_leaf_fn(LibraryIDLinkCallbackData *cb_data)
+{
+  ID *id_owner = cb_data->id_owner;
+  ID *id = *cb_data->id_pointer;
+  bool *is_leaf = cb_data->user_data;
+
+  if (id != NULL && ID_IS_OVERRIDE_LIBRARY_REAL(id) &&
+      id->override_library->hierarchy_root == id_owner->override_library->hierarchy_root) {
+    *is_leaf = false;
+    return IDWALK_RET_STOP_ITER;
+  }
+  return IDWALK_RET_NOP;
+}
+
+bool BKE_lib_override_library_is_hierarchy_leaf(Main *bmain, ID *id)
+{
+  if (ID_IS_OVERRIDE_LIBRARY_REAL(id)) {
+    bool is_leaf = true;
+    BKE_library_foreach_ID_link(
+        bmain, id, foreachid_is_hierarchy_leaf_fn, &is_leaf, IDWALK_READONLY);
+    return is_leaf;
+  }
+
+  return false;
+}
+
 ID *BKE_lib_override_library_create_from_id(Main *bmain,
                                             ID *reference_id,
                                             const bool do_tagged_remap)
@@ -3058,10 +3084,16 @@ bool BKE_lib_override_library_main_operations_create(Main *bmain, const bool for
   return create_pool_data.changed;
 }
 
-static bool lib_override_library_id_reset_do(Main *bmain, ID *id_root)
+static bool lib_override_library_id_reset_do(Main *bmain,
+                                             ID *id_root,
+                                             const bool do_reset_system_override)
 {
   bool was_op_deleted = false;
 
+  if (do_reset_system_override) {
+    id_root->override_library->flag |= IDOVERRIDE_LIBRARY_FLAG_SYSTEM_DEFINED;
+  }
+
   LISTBASE_FOREACH_MUTABLE (
       IDOverrideLibraryProperty *, op, &id_root->override_library->properties) {
     bool do_op_delete = true;
@@ -3117,13 +3149,15 @@ static bool lib_override_library_id_reset_do(Main *bmain, ID *id_root)
   return was_op_deleted;
 }
 
-void BKE_lib_override_library_id_reset(Main *bmain, ID *id_root)
+void BKE_lib_override_library_id_reset(Main *bmain,
+                                       ID *id_root,
+                                       const bool do_reset_system_override)
 {
   if (!ID_IS_OVERRIDE_LIBRARY_REAL(id_root)) {
     return;
   }
 
-  if (lib_override_library_id_reset_do(bmain, id_root)) {
+  if (lib_override_library_id_reset_do(bmain, id_root, do_reset_system_override)) {
     if (id_root->override_library->runtime != NULL &&
         (id_root->override_library->runtime->tag & IDOVERRIDE_LIBRARY_RUNTIME_TAG_NEEDS_RELOAD) !=
             0) {
@@ -3133,7 +3167,9 @@ void BKE_lib_override_library_id_reset(Main *bmain, ID *id_root)
   }
 }
 
-static void lib_override_library_id_hierarchy_recursive_reset(Main *bmain, ID *id_root)
+static void lib_override_library_id_hierarchy_recursive_reset(Main *bmain,
+                                                              ID *id_root,
+                                                              const bool do_reset_system_override)
 {
   if (!ID_IS_OVERRIDE_LIBRARY_REAL(id_root)) {
     return;
@@ -3142,7 +3178,7 @@ static void lib_override_library_id_hierarchy_recursive_reset(Main *bmain, ID *i
   void **entry_vp = BLI_ghash_lookup_p(bmain->relations->relations_from_pointers, id_root);
   if (entry_vp == NULL) {
     /* This ID is not used by nor using any other ID. */
-    lib_override_library_id_reset_do(bmain, id_root);
+    lib_override_library_id_reset_do(bmain, id_root, do_reset_system_override);
     return;
   }
 
@@ -3152,7 +3188,7 @@ static void lib_override_library_id_hierarchy_recursive_reset(Main *bmain, ID *i
     return;
   }
 
-  lib_override_library_id_reset_do(bmain, id_root);
+  lib_override_library_id_reset_do(bmain, id_root, do_reset_system_override);
 
   /* This way we won't process again that ID, should we encounter it again through another
    * relationship hierarchy. */
@@ -3169,17 +3205,19 @@ static void lib_override_library_id_hierarchy_recursive_reset(Main *bmain, ID *i
     if (*to_id_entry->id_pointer.to != NULL) {
       ID *to_id = *to_id_entry->id_pointer.to;
       if (to_id->override_library != NULL) {
-        lib_override_library_id_hierarchy_recursive_reset(bmain, to_id);
+        lib_override_library_id_hierarchy_recursive_reset(bmain, to_id, do_reset_system_override);
       }
     }
   }
 }
 
-void BKE_lib_override_library_id_hierarchy_reset(Main *bmain, ID *id_root)
+void BKE_lib_override_library_id_hierarchy_reset(Main *bmain,
+                                                 ID *id_root,
+                                                 const bool do_reset_system_override)
 {
   BKE_main_relations_create(bmain, 0);
 
-  lib_override_library_id_hierarchy_recursive_reset(bmain, id_root);
+  lib_override_library_id_hierarchy_recursive_reset(bmain, id_root, do_reset_system_override);
 
   BKE_main_relations_free(bmain);
 
diff --git a/source/blender/editors/space_outliner/outliner_edit.cc b/source/blender/editors/space_outliner/outliner_edit.cc
index ae67e7108bf..d6c5901b546 100644
--- a/source/blender/editors/space_outliner/outliner_edit.cc
+++ b/source/blender/editors/space_outliner/outliner_edit.cc
@@ -30,6 +30,7 @@
 #include "BKE_context.h"
 #include "BKE_idtype.h"
 #include "BKE_lib_id.h"
+#include "BKE_lib_override.h"
 #include "BKE_lib_query.h"
 #include "BKE_lib_remap.h"
 #include "BKE_main.h"
diff --git a/source/blender/editors/space_outliner/outliner_tools.cc b/source/blender/editors/space_outliner/outliner_tools.cc
index 6593fb9b6af..22e42c762ca 100644
--- a/source/blender/editors/space_outliner/outliner_tools.cc
+++ b/source/blender/editors/space_outliner/outliner_tools.cc
@@ -47,6 +47,7 @@
 #include "BKE_lib_id.h"
 #include "BKE_lib_override.h"
 #include "BKE_lib_query.h"
+#include "BKE_lib_remap.h"
 #include "BKE_main.h"
 #include "BKE_object.h"
 #include "BKE_report.h"
@@ -1008,6 +1009,23 @@ static void id_override_library_create_hierarchy_post_process(bContext *C,
   FOREACH_MAIN_ID_END;
 }
 
+static void id_override_library_toggle_flag_fn(bContext *UNUSED(C),
+                                               ReportList *UNUSED(reports),
+                                               Scene *UNUSED(scene),
+                                               TreeElement *UNUSED(te),
+                                               TreeStoreElem *UNUSED(tsep),
+                                               TreeStoreElem *tselem,
+                                               void *user_data)
+{
+  BLI_assert(TSE_IS_REAL_ID(tselem));
+  ID *id = tselem->id;
+
+  if (ID_IS_OVERRIDE_LIBRARY_REAL(id)) {
+    const uint flag = POINTER_AS_UINT(user_data);
+    id->override_library->flag ^= flag;
+  }
+}
+
 static void id_override_library_reset_fn(bContext *C,
                                          ReportList *UNUSED(reports),
                                          Scene *UNUSED(scene),
@@ -1025,10 +1043,10 @@ static void id_override_library_reset_fn(bContext *C,
     Main *bmain = CTX_data_main(C);
 
     if (do_hierarchy) {
-      BKE_lib_override_library_id_hierarchy_reset(bmain, id_root);
+      BKE_lib_override_library_id_hierarchy_reset(bmain, id_root, false);
     }
     else {
-      BKE_lib_override_library_id_reset(bmain, id_root);
+      BKE_lib_override_library_id_reset(bmain, id_root, false);
     }
 
     WM_event_add_notifier(C, NC_WM | ND_DATACHANGED, nullptr);
@@ -1080,40 +1098,76 @@ static void id_override_library_resync_fn(bContext *C,
   }
 }
 
-static void id_override_library_delete_fn(bContext *C,
-                                          ReportList *UNUSED(reports),
-                                          Scene *UNUSED(scene),
-                                          TreeElement *te,
-                                          TreeStoreElem *UNUSED(tsep),
-                                          TreeStoreElem *tselem,
-                                          void *UNUSED(user_data))
+static void id_override_library_clear_hierarchy_fn(bContext *C,
+                                                   ReportList *UNUSED(reports),
+                                                   Scene *UNUSED(scene),
+                                                   TreeElement *te,
+                                                   TreeStoreElem *UNUSED(tsep),
+                                                   TreeStoreElem *tselem,
+                                                   void *UNUSED(user_data))
 {
   BLI_assert(TSE_IS_REAL_ID(tselem));
   ID *id_root = tselem->id;
 
-  if (ID_IS_OVERRIDE_LIBRARY_REAL(id_root)) {
-    Main *bmain = CTX_data_main(C);
+  if (!ID_IS_OVERRIDE_LIBRARY_REAL(id_root)) {
+    CLOG_WARN(&LOG, "Could not delete library override of data block '%s'", id_root->name);
+    return;
+  }
 
-    id_root->tag |= LIB_TAG_DOIT;
+  Main *bmain = CTX_data_main(C);
 
-    /* Tag all linked parents in tree hierarchy to be also overridden. */
-    while ((te = te->parent) != nullptr) {
-      if (!TSE_IS_REAL_ID(te->store_elem)) {
-        continue;
-      }
-      if (!ID_IS_OVERRIDE_LIBRARY_REAL(te->store_elem->id)) {
-        break;
-      }
-      te->store_elem->id->tag |= LIB_TAG_DOIT;
+  id_root->tag |= LIB_TAG_DOIT;
+
+  /* Tag all override parents in tree hierarchy to be also processed. */
+  while ((te = te->parent) != nullptr) {
+    if (!TSE_IS_REAL_ID(te->store_elem)) {
+      continue;
+    }
+    if (!ID_IS_OVERRIDE_LIBRARY_REAL(te->store_elem->id)) {
+      break;
     }
+    te->store_elem->id->tag |= LIB_TAG_DOIT;
+  }
 
-    BKE_lib_override_library_delete(bmain, id_root);
+  BKE_lib_override_library_delete(bmain, id_root);
 
-    WM_event_add_notifier(C, NC_WINDOW, nullptr);
+  WM_event_add_notifier(C, NC_WINDOW, nullptr);
+}
+
+static void id_override_library_clear_single_fn(bContext *C,
+                                                ReportList *reports,
+                                                Scene *UNUSED(scene),
+                                                TreeElement *UNUSED(te),
+                                                TreeStoreElem *UNUSED(tsep),
+                                                TreeStoreElem *tselem,
+                                                void *UNUSED(user_data))
+{
+  BLI_assert(TSE_IS_REAL_ID(tselem));
+  Main *bmain = CTX_data_main(C);
+  ID *id = tselem->id;
+
+  if (!ID_IS_OVERRIDE_LIBRARY_REAL(id)) {
+    BKE_reportf(reports,
+                RPT_WARNING,
+                "Cannot clear embedded library override id '%s', only overrides of real "
+                "data-blocks can be directly deleted",
+                id->name);
+    return;
+  }
+
+  /* If given ID is not using any other override (it's a 'leaf' in the override hierarchy),
+   * delete it and remap its usages to its linked reference. Otherwise, keep it as a reset system
+   * override. */
+  if (BKE_lib_override_library_is_hierarchy_leaf(bmain, id)) {
+    BKE_libblock_remap(bmain, id, id->override_library->reference, ID_REMAP_SKIP_INDIRECT_USAGE);
+    BKE_id_delete(bmain, id);
   }
   else {
-    CLOG_WARN(&LOG, "Could not delete library override of data block '%s'", id_root->name);
+    BKE_lib_override_library_id_reset(bmain, id, true);
   }
+
+  WM_event_add_notifier(C, NC_WINDOW, nullptr);
+  return;
 }
 
 static void id_fake_user_set_fn(bContext *UNUSED(C),
@@ -1911,11 +1965,13 @@ enum eOutlinerIdOpTypes {
   OUTLINER_IDOP_LOCAL,
   OUTLINER_IDOP_OVERRIDE_LIBRARY_CREATE,
   OUTLINER_IDOP_OVERRIDE_LIBRARY_CREATE_HIERARCHY,
+  OUTLINER_IDOP_OVERRIDE_LIBRARY_MAKE_EDITABLE,
   OUTLINER_IDOP_OVERRIDE_LIBRARY_RESET,
   OUTLINER_IDOP_OVERRIDE_LIBRARY_RESET_HIERARCHY,
   OUTLINER_IDOP_OVERRIDE_LIBRARY_RESYNC_HIERARCHY,
   OUTLINER_IDOP_OVERRIDE_LIBRARY_RESYNC_HIERARCHY_ENFORCE,
-  OUTLINER_IDOP_OVERRIDE_LIBRARY_DELETE_HIERARCHY,
+  OUTLINER_IDOP_OVERRIDE_LIBRARY_CLEAR_HIERARCHY,
+  OUTLINER_IDOP_OVERRIDE_LIBRARY_CLEAR_SINGLE,
   OUTLINER_IDOP_SINGLE,
   OUTLINER_IDOP_DELETE,
   OUTLINER_IDOP_REMAP,
@@ -1954,6 +2010,11 @@ static const EnumPropertyItem prop_id_op_types[] = {
      "Make Library Override Hierarchy",
      "Make a local override of this linked data-block, and its hierarchy of dependencies - only "
      "applies to active Outliner item"},
+    {OUTLINER_IDOP_OVERRIDE_LIBRARY_MAKE_EDITABLE,
+     "OVERRIDE_LIBRARY_MAKE_EDITABLE",
+     0,
+     "Make Library Override Editable",
+     "Make the library override data-block editable"},
     {OUTLINER_IDOP_OVERRIDE_LIBRARY_RESET,
      "OVERRIDE_LIBRARY_RESET",
      0,
@@ -1977,12 +2038,18 @@ static const EnumPropertyItem prop_id_op_types[] = {
      "Rebuild this local override from its linked reference, as well as its hierarchy of "
      "dependencies, enforcing that hierarchy to match the linked data (i.e. ignoring exiting "
      "overrides on data-blocks pointer properties)"},
-    {OUTLINER_IDOP_OVERRIDE_LIBRARY_DELETE_HIERARCHY,
-     "OVERRIDE_LIBRARY_DELETE_HIERARCHY",
+    {OUTLINER_IDOP_OVERRIDE_LIBRARY_CLEAR_HIERARCHY,
+     "OVERRIDE_LIBRARY_CLEAR_HIERARCHY",
      0,
-     "Delete Library Override Hierarchy",
+     "Clear Library Override Hierarchy",
      "Delete this local override (including its hierarchy of override dependencies) and relink "
      "its usages to the linked data-blocks"},
+    {OUTLINER_IDOP_OVERRIDE_LIBRARY_CLEAR_SINGLE,
+     "OVERRIDE_LIBRARY_CLEAR_SINGLE",
+     0,
+     "Clear Single Library Override",
+     "Delete this local override if possible, else reset it and mark it as non editable, and "
+     "relink its usages to the linked data-blocks"},
     {0, "", 0, nullptr, nullptr},
     {OUTLINER_IDOP_COPY, "COPY", ICON_COPYDOWN, "Copy", ""},
     {OUTLINER_IDOP_PASTE, "PASTE", ICON_PASTEDOWN, "Paste", ""},
@@ -2026,11 +2093,19 @@ static bool outliner_id_operation_item_poll(bContext *C,
         return true;
       }
       return false;
+    case OUTLINER_IDOP_OVERRIDE_LIBRARY_MAKE_EDITABLE:
+      if (ID_IS_OVERRIDE_LIBRARY_REAL(tselem->id) && !ID_IS_LINKED(tselem->id)) {
+        if (tselem->id->override_library->flag & IDOVERRIDE_LIBRARY_FLAG_SYSTEM_DEFINED) {
+          return true;
+        }
+      }
+      return false;
     case OUTLINER_IDOP_OVERRIDE_LIBRARY_RESET:
     case OUTLINER_IDOP_OVERRIDE_LIBRARY_RESET_HIERARCHY:
     case OUTLINER_IDOP_OVERRIDE_LIBRARY_RESYNC_HIERARCHY:
     case OUTLINER_IDOP_OVERRIDE_LIBRARY_RESYNC_HIERARCHY_ENFORCE:
-    case OUTLINER_IDOP_OVERRIDE_LIBRARY_DELETE_HIERARCHY:
+    case OUTLINER_IDOP_OVERRIDE_LIBRARY_CLEAR_HIERARCHY:
+    case OUTLINER_IDOP_OVERRIDE_LIBRARY_CLEAR_SINGLE:
       if (ID_IS_OVERRIDE_LIBRARY_REAL(tselem->id) && !ID_IS_LINKED(tselem->id)) {
         return true;
       }
@@ -2211,6 +2286,18 @@ static int outliner_id_operation_exec(bContext *C, wmOperator *op)
       ED_undo_push(C, "Overridden Data Hierarchy");
       break;
     }
+    case OUTLINER_IDOP_OVERRIDE_LIBRARY_MAKE_EDITABLE: {
+      outliner_do_libdata_operation(C,
+                                    op->reports,
+                                    scene,
+                                    space_outliner,
+                                    &space_outliner->tree,
+                                    id_override_library_toggle_flag_fn,
+                                    POINTER_FROM_UINT(IDOVERRIDE_LIBRARY_FLAG_SYSTEM_DEFINED));
+
+      ED_undo_push(C, "Make Overridden Data Editable");
+      break;
+    }
     case OUTLINER_IDOP_OVERRIDE_LIBRARY_RESET: {
       OutlinerLibOverrideData override_data{};
       outliner_do_libdata_operation(C,
@@ -2263,17 +2350,26 @@ static int outliner_id_operation_exec(bContext *C, wmOperator *op)
       ED_undo_push(C, "Resync Overridden Data Hierarchy");
       break;
     }
-    case OUTLINER_IDOP_OVERRIDE_LIBRARY_DELETE_HIERARCHY: {
-      OutlinerLibOverrideData override_data{};
-      override_data.do_hierarchy = true;
+    case OUTLINER_IDOP_OVERRIDE_LIBRARY_CLEAR_HIERARCHY: {
       outliner_do_libdata_operation(C,
                                     op->reports,
                                     scene,
                                     space_outliner,
                                     &space_outliner->tree,
-                                    id_override_library_delete_fn,
-                                    &override_data);
-      ED_undo_push(C, "Delete Overridden Data Hierarchy");
+                                    id_override_library_clear_hierarchy_fn,
+                                    nullptr);
+      ED_undo_push(C, "Clear Overridden Data Hierarchy");
+      break;
+    }
+    case OUTLINER_IDOP_OVERRIDE_LIBRARY_CLEAR_SINGLE: {
+      outliner_do_libdata_operation(C,
+                                    op->reports,
+                                    scene,
+                                    space_outliner,
+                                    &space_outliner->tree,
+                                    id_override_library_clear_single_fn,
+                                    nullptr);
+      ED_undo_push(C, "Clear Overridden Data Hierarchy");
       break;
     }
     case OUTLINER_IDOP_SINGLE: {
diff --git a/source/blender/makesrna/intern/rna_ID.c b/source/blender/makesrna/intern/rna_ID.c
index 5f264a19d47..d3b7e380afa 100644
--- a/source/blender/makesrna/intern/rna_ID.c
+++ b/source/blender/makesrna/intern/rna_ID.c
@@ -762,7 +762,8 @@ static void rna_ID_override_library_reset(ID *id,
                                           IDOverrideLibrary *UNUSED(override_library),
                                           Main *bmain,
                                           ReportList *reports,
-                                          bool do_hierarchy)
+                                          bool do_hierarchy,
+                                          bool set_system_override)
 {
   if (!ID_IS_OVERRIDE_LIBRARY_REAL(id)) {
     BKE_reportf(reports, RPT_ERROR, "ID '%s' isn't an override", id->name);
@@ -770,10 +771,10 @@ static void rna_ID_override_library_reset(ID *id,
   }
 
   if (do_hierarchy) {
-    BKE_lib_override_library_id_hierarchy_reset(bmain, id);
+    BKE_lib_override_library_id_hierarchy_reset(bmain, id, set_system_override);
   }
   else {
-    BKE_lib_override_library_id_reset(bmain, id);
+    BKE_lib_override_library_id_reset(bmain, id, set_system_override);
   }
 
   WM_main_add_notifier(NC_WM | ND_LIB_OVERRIDE_CHANGED, NULL);
@@ -1869,6 +1870,11 @@ static void rna_def_ID_override_library(BlenderRNA *brna)
       true,
       "",
       "Also reset all the dependencies of this override to match their reference linked IDs");
+  RNA_def_boolean(func,
+                  "set_system_override",
+                  false,
+                  "",
+                  "Reset all user-editable overrides as (non-editable) system overrides");
 
   func = RNA_def_function(srna, "destroy", "rna_ID_override_library_destroy");
   RNA_def_function_ui_description(