LibOverride: Add initial handling of system overrides in creation/duplication/resync code, and some basic do_version.

When creating with hierarchies, core code only generates system
overrides, responsibility to define 'user overrides' is then for the
higher-level calling code (Editor/Operator-level).

do_version code uses fairly basic euristics, should be good enough here
though in most cases. and can always be refined later if needed.

Ref: {T95707}.

source/blender/blenkernel/BKE_blender_version.h

@@ -25,7 +25,7 @@ extern "C" {
 
 /* Blender file format version. */
 #define BLENDER_FILE_VERSION BLENDER_VERSION
-#define BLENDER_FILE_SUBVERSION 6
+#define BLENDER_FILE_SUBVERSION 7
 
 /* Minimum Blender version that supports reading file written with the current
  * version. Older Blender versions will test this and show a warning if the file

source/blender/blenkernel/intern/lib_override.c

@@ -122,6 +122,9 @@ IDOverrideLibrary *BKE_lib_override_library_init(ID *local_id, ID *reference_id)
   local_id->override_library->reference = reference_id;
   id_us_plus(local_id->override_library->reference);
   local_id->tag &= ~LIB_TAG_OVERRIDE_LIBRARY_REFOK;
+  /* By default initialized libioverrides are 'system overrides', higher-level code is responsible
+   * to unset this flag for specific IDs. */
+  local_id->override_library->flag |= IDOVERRIDE_LIBRARY_FLAG_SYSTEM_DEFINED;
   /* TODO: do we want to add tag or flag to referee to mark it as such? */
   return local_id->override_library;
 }
@@ -300,6 +303,7 @@ ID *BKE_lib_override_library_create_from_id(Main *bmain,
    * 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;
+  local_id->override_library->flag &= ~IDOVERRIDE_LIBRARY_FLAG_SYSTEM_DEFINED;
   local_id->override_library->hierarchy_root = local_id;
 
   if (do_tagged_remap) {
@@ -1647,6 +1651,8 @@ static bool lib_override_library_resync(Main *bmain,
           if (ID_IS_OVERRIDE_LIBRARY_REAL(id_override_new)) {
             BLI_assert(ID_IS_OVERRIDE_LIBRARY_REAL(id_override_old));
 
+            id_override_new->override_library->flag = id_override_old->override_library->flag;
+
             /* Copy over overrides rules from old override ID to new one. */
             BLI_duplicatelist(&id_override_new->override_library->properties,
                               &id_override_old->override_library->properties);

source/blender/blenkernel/intern/lib_override_proxy_conversion.c

@@ -62,6 +62,7 @@ bool BKE_lib_override_library_proxy_convert(Main *bmain,
   ob_proxy->proxy->id.tag |= LIB_TAG_DOIT;
   ob_proxy->proxy->id.newid = &ob_proxy->id;
   BKE_lib_override_library_init(&ob_proxy->id, &ob_proxy->proxy->id);
+  ob_proxy->id.override_library->flag &= ~IDOVERRIDE_LIBRARY_FLAG_SYSTEM_DEFINED;
 
   ob_proxy->proxy->proxy_from = NULL;
   ob_proxy->proxy = ob_proxy->proxy_group = NULL;

source/blender/blenloader/intern/versioning_300.c

@@ -2435,17 +2435,27 @@ void blo_do_versions_300(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
   }
 
-  /**
-   * Versioning code until next subversion bump goes here.
-   *
-   * \note Be sure to check when bumping the version:
-   * - "versioning_userdef.c", #blo_do_versions_userdef
-   * - "versioning_userdef.c", #do_versions_theme
-   *
-   * \note Keep this message at the bottom of the function.
-   */
-  {
-    /* Keep this block, even when empty. */
+  if (!MAIN_VERSION_ATLEAST(bmain, 302, 7)) {
+    /* Generate 'system' liboverrides IDs.
+     * NOTE: This is a fairly rough process, based on very basic euristics. Should be enough for a
+     * do_version code though, this is a new optional feature, not a critical conversion. */
+    ID *id;
+    FOREACH_MAIN_ID_BEGIN (bmain, id) {
+      if (!ID_IS_OVERRIDE_LIBRARY_REAL(id) || ID_IS_LINKED(id)) {
+        /* Ignore non-real liboverrides, and linked ones. */
+        continue;
+      }
+      if (GS(id->name) == ID_OB) {
+        /* Never 'lock' an object into a system override for now. */
+        continue;
+      }
+      if (BKE_lib_override_library_is_user_edited(id)) {
+        /* Do not 'lock' an ID already edited by the user. */
+        continue;
+      }
+      id->override_library->flag |= IDOVERRIDE_LIBRARY_FLAG_SYSTEM_DEFINED;
+    }
+    FOREACH_MAIN_ID_END;
 
     /* Initialize brush curves sculpt settings. */
     LISTBASE_FOREACH (Brush *, brush, &bmain->brushes) {
@@ -2476,4 +2486,17 @@ void blo_do_versions_300(FileData *fd, Library *UNUSED(lib), Main *bmain)
       }
     }
   }
+
+  /**
+   * Versioning code until next subversion bump goes here.
+   *
+   * \note Be sure to check when bumping the version:
+   * - "versioning_userdef.c", #blo_do_versions_userdef
+   * - "versioning_userdef.c", #do_versions_theme
+   *
+   * \note Keep this message at the bottom of the function.
+   */
+  {
+    /* Keep this block, even when empty. */
+  }
 }