[Bf-blender-cvs] [bfb760e16ac] master: Fix T94650: LibOverride: Bad handling of (auto)resync in case of single override.

[Bastien Montagne]

Commit: bfb760e16acbc33661739154f0ab8f5505987d1d
Author: Bastien Montagne
Date:   Wed Jan 5 16:30:15 2022 +0100
Branches: master
https://developer.blender.org/rBbfb760e16acbc33661739154f0ab8f5505987d1d

Fix T94650: LibOverride: Bad handling of (auto)resync in case of single override.

Overrides that are not created as part of an override hierarchy should
not be handled through (auto)resync at all. users are responsible to
hanlde those updates if they need it.

This is achieved by flagging overrides created outside of a hierarchical
process accordingly, and skipping them during resync process.

===================================================================

M	source/blender/blenkernel/BKE_lib_override.h
M	source/blender/blenkernel/intern/lib_override.c
M	source/blender/makesdna/DNA_ID.h
M	source/blender/makesrna/intern/rna_ID.c
M	source/blender/makesrna/intern/rna_access_compare_override.c

===================================================================

diff --git a/source/blender/blenkernel/BKE_lib_override.h b/source/blender/blenkernel/BKE_lib_override.h
index 1c30db7a714..6e4864d8abc 100644
--- a/source/blender/blenkernel/BKE_lib_override.h
+++ b/source/blender/blenkernel/BKE_lib_override.h
@@ -84,6 +84,9 @@ bool BKE_lib_override_library_is_user_edited(struct ID *id);
 
 /**
  * Create an overridden local copy of linked reference.
+ *
+ * \note This function is very basic, low-level. It does not consider any hierarcical dependency,
+ * and also prevents any automatic resync of this local override.
  */
 struct ID *BKE_lib_override_library_create_from_id(struct Main *bmain,
                                                    struct ID *reference_id,
diff --git a/source/blender/blenkernel/intern/lib_override.c b/source/blender/blenkernel/intern/lib_override.c
index 07ec8d32ad0..b0231585f68 100644
--- a/source/blender/blenkernel/intern/lib_override.c
+++ b/source/blender/blenkernel/intern/lib_override.c
@@ -282,6 +282,10 @@ ID *BKE_lib_override_library_create_from_id(Main *bmain,
   BLI_assert(ID_IS_LINKED(reference_id));
 
   ID *local_id = lib_override_library_create_from(bmain, reference_id, 0);
+  /* We cannot allow automatic hierarchy resync on this ID, it is highly likely to generate a giant
+   * mess in case there are a lot of hidden, non-instantiated, non-properly organized dependencies.
+   * Ref T94650. */
+  local_id->override_library->flag |= IDOVERRIDE_LIBRARY_FLAG_NO_HIERARCHY;
 
   if (do_tagged_remap) {
     Key *reference_key, *local_key = NULL;
@@ -734,6 +738,11 @@ static void lib_override_overrides_group_tag_recursive(LibOverrideGroupTagData *
   ID *id_owner = data->id_root;
   BLI_assert(ID_IS_OVERRIDE_LIBRARY(id_owner));
   BLI_assert(data->is_override);
+
+  if (id_owner->override_library->flag & IDOVERRIDE_LIBRARY_FLAG_NO_HIERARCHY) {
+    return;
+  }
+
   const uint tag = data->tag;
   const uint missing_tag = data->missing_tag;
 
@@ -1643,6 +1652,11 @@ static void lib_override_library_main_resync_on_library_indirect_level(
       continue;
     }
 
+    if (id->override_library->flag & IDOVERRIDE_LIBRARY_FLAG_NO_HIERARCHY) {
+      /* This ID is not part of an override hierarchy. */
+      continue;
+    }
+
     data.id_root = id->override_library->reference;
     lib_override_linked_group_tag(&data);
     BKE_main_relations_tag_set(bmain, MAINIDRELATIONS_ENTRY_TAGS_PROCESSED, false);
@@ -1660,6 +1674,12 @@ static void lib_override_library_main_resync_on_library_indirect_level(
       continue;
     }
 
+    if (id->override_library->flag & IDOVERRIDE_LIBRARY_FLAG_NO_HIERARCHY) {
+      /* This ID is not part of an override hierarchy. */
+      BLI_assert((id->tag & LIB_TAG_LIB_OVERRIDE_NEED_RESYNC) == 0);
+      continue;
+    }
+
     if (id->tag & LIB_TAG_LIB_OVERRIDE_NEED_RESYNC) {
       CLOG_INFO(&LOG, 4, "ID %s (%p) was already tagged as needing resync", id->name, id->lib);
       lib_override_resync_tagging_finalize_recurse(bmain, id, library_indirect_level);
diff --git a/source/blender/makesdna/DNA_ID.h b/source/blender/makesdna/DNA_ID.h
index 17b3fb302e6..9fdf7be04e2 100644
--- a/source/blender/makesdna/DNA_ID.h
+++ b/source/blender/makesdna/DNA_ID.h
@@ -315,8 +315,22 @@ typedef struct IDOverrideLibrary {
   struct ID *storage;
 
   IDOverrideLibraryRuntime *runtime;
+
+  void *_pad_0;
+
+  unsigned int flag;
+  char _pad_1[4];
 } IDOverrideLibrary;
 
+/* IDOverrideLibrary->flag */
+enum {
+  /**
+   * The override data-block should not be considered as part of an override hierarchy (generally
+   * because it was created as an single override, outside of any hierarchy consideration).
+   */
+  IDOVERRIDE_LIBRARY_FLAG_NO_HIERARCHY = 1 << 0,
+};
+
 /* watch it: Sequence has identical beginning. */
 /**
  * ID is the first thing included in all serializable types. It
diff --git a/source/blender/makesrna/intern/rna_ID.c b/source/blender/makesrna/intern/rna_ID.c
index be612a1602b..c43b80204cf 100644
--- a/source/blender/makesrna/intern/rna_ID.c
+++ b/source/blender/makesrna/intern/rna_ID.c
@@ -1808,6 +1808,14 @@ static void rna_def_ID_override_library(BlenderRNA *brna)
   RNA_def_pointer(
       srna, "reference", "ID", "Reference ID", "Linked ID used as reference by this override");
 
+  prop = RNA_def_boolean(srna,
+                         "is_in_hierarchy",
+                         true,
+                         "Is In Hierarchy",
+                         "Whether this library override is defined as part of a library "
+                         "hierarchy, or as a single, isolated and autonomous override");
+  RNA_def_property_boolean_negative_sdna(prop, NULL, "flag", IDOVERRIDE_LIBRARY_FLAG_NO_HIERARCHY);
+
   prop = RNA_def_collection(srna,
                             "properties",
                             "IDOverrideLibraryProperty",
diff --git a/source/blender/makesrna/intern/rna_access_compare_override.c b/source/blender/makesrna/intern/rna_access_compare_override.c
index 19c678a4222..2af83c8adcb 100644
--- a/source/blender/makesrna/intern/rna_access_compare_override.c
+++ b/source/blender/makesrna/intern/rna_access_compare_override.c
@@ -1095,6 +1095,13 @@ static void rna_property_override_check_resync(Main *bmain,
   ID *id_src = rna_property_override_property_real_id_owner(bmain, ptr_item_src, NULL, NULL);
   ID *id_dst = rna_property_override_property_real_id_owner(bmain, ptr_item_dst, NULL, NULL);
 
+  BLI_assert(ID_IS_OVERRIDE_LIBRARY_REAL(id_owner));
+
+  /* If the owner ID is not part of an override hierarchy, there is no possible resync. */
+  if (id_owner->override_library->flag & IDOVERRIDE_LIBRARY_FLAG_NO_HIERARCHY) {
+    return;
+  }
+
   /* If `id_src` is not a liboverride, we cannot perform any further 'need resync' checks from
    * here. */
   if (id_src != NULL && !ID_IS_OVERRIDE_LIBRARY_REAL(id_src)) {