Fix T75730: Properly remove unused override properties/operations.

While code is supposed to handle gracefully invalid override operations,
it is much cleaner to avoid those completely.

source/blender/blenkernel/BKE_lib_override.h

@@ -111,6 +111,17 @@ bool BKE_lib_override_library_operations_create(struct Main *bmain,
                                                 const bool force_auto);
 void BKE_lib_override_library_main_operations_create(struct Main *bmain, const bool force_auto);
 
+void BKE_lib_override_library_operations_tag(struct IDOverrideLibraryProperty *override_property,
+                                             const short tag,
+                                             const bool do_set);
+void BKE_lib_override_library_properties_tag(struct IDOverrideLibrary *override,
+                                             const short tag,
+                                             const bool do_set);
+void BKE_lib_override_library_main_tag(struct Main *bmain, const short tag, const bool do_set);
+
+void BKE_lib_override_library_id_unused_cleanup(struct ID *local);
+void BKE_lib_override_library_main_unused_cleanup(struct Main *bmain);
+
 void BKE_lib_override_library_update(struct Main *bmain, struct ID *local);
 void BKE_lib_override_library_main_update(struct Main *bmain);
 

source/blender/blenkernel/intern/lib_override.c

@@ -744,8 +744,8 @@ bool BKE_lib_override_library_operations_create(Main *bmain, ID *local, const bo
 
     if (GS(local->name) == ID_OB) {
       /* Our beloved pose's bone cross-data pointers... Usually, depsgraph evaluation would ensure
-       * this is valid, but in some cases (like hidden collections etc.) this won't be the case, so
-       * we need to take care of this ourselves. */
+       * this is valid, but in some situations (like hidden collections etc.) this won't be the
+       * case, so we need to take care of this ourselves. */
       Object *ob_local = (Object *)local;
       if (ob_local->data != NULL && ob_local->type == OB_ARMATURE && ob_local->pose != NULL &&
           ob_local->pose->flag & POSE_RECALC) {
@@ -788,6 +788,12 @@ void BKE_lib_override_library_main_operations_create(Main *bmain, const bool for
 {
   ID *id;
 
+  /* When force-auto is set, we also remove all unused existing override properties & operations.
+   */
+  if (force_auto) {
+    BKE_lib_override_library_main_tag(bmain, IDOVERRIDE_LIBRARY_TAG_UNUSED, true);
+  }
+
   FOREACH_MAIN_ID_BEGIN (bmain, id) {
     if ((ID_IS_OVERRIDE_LIBRARY(id) && force_auto) ||
         (ID_IS_OVERRIDE_LIBRARY_AUTO(id) && (id->tag & LIB_TAG_OVERRIDE_LIBRARY_AUTOREFRESH))) {
@@ -796,6 +802,92 @@ void BKE_lib_override_library_main_operations_create(Main *bmain, const bool for
     }
   }
   FOREACH_MAIN_ID_END;
+
+  if (force_auto) {
+    BKE_lib_override_library_main_unused_cleanup(bmain);
+  }
+}
+
+/** Set or clear given tag in all operations as unused in that override property data. */
+void BKE_lib_override_library_operations_tag(struct IDOverrideLibraryProperty *override_property,
+                                             const short tag,
+                                             const bool do_set)
+{
+  if (override_property != NULL) {
+    if (do_set) {
+      override_property->tag |= tag;
+    }
+    else {
+      override_property->tag &= ~tag;
+    }
+
+    LISTBASE_FOREACH (IDOverrideLibraryPropertyOperation *, opop, &override_property->operations) {
+      if (do_set) {
+        opop->tag |= tag;
+      }
+      else {
+        opop->tag &= ~tag;
+      }
+    }
+  }
+}
+
+/** Set or clear given tag in all properties and operations in that override data. */
+void BKE_lib_override_library_properties_tag(struct IDOverrideLibrary *override,
+                                             const short tag,
+                                             const bool do_set)
+{
+  if (override != NULL) {
+    LISTBASE_FOREACH (IDOverrideLibraryProperty *, op, &override->properties) {
+      BKE_lib_override_library_operations_tag(op, tag, do_set);
+    }
+  }
+}
+
+/** Set or clear given tag in all properties and operations in that Main's ID override data. */
+void BKE_lib_override_library_main_tag(struct Main *bmain, const short tag, const bool do_set)
+{
+  ID *id;
+
+  FOREACH_MAIN_ID_BEGIN (bmain, id) {
+    if (ID_IS_OVERRIDE_LIBRARY(id)) {
+      BKE_lib_override_library_properties_tag(id->override_library, tag, do_set);
+    }
+  }
+  FOREACH_MAIN_ID_END;
+}
+
+/** Remove all tagged-as-unused properties and operations from that ID override data. */
+void BKE_lib_override_library_id_unused_cleanup(struct ID *local)
+{
+  if (local->override_library != NULL) {
+    LISTBASE_FOREACH_MUTABLE (
+        IDOverrideLibraryProperty *, op, &local->override_library->properties) {
+      if (op->tag & IDOVERRIDE_LIBRARY_TAG_UNUSED) {
+        BKE_lib_override_library_property_delete(local->override_library, op);
+      }
+      else {
+        LISTBASE_FOREACH_MUTABLE (IDOverrideLibraryPropertyOperation *, opop, &op->operations) {
+          if (opop->tag & IDOVERRIDE_LIBRARY_TAG_UNUSED) {
+            BKE_lib_override_library_property_operation_delete(op, opop);
+          }
+        }
+      }
+    }
+  }
+}
+
+/** Remove all tagged-as-unused properties and operations from that Main's ID override data. */
+void BKE_lib_override_library_main_unused_cleanup(struct Main *bmain)
+{
+  ID *id;
+
+  FOREACH_MAIN_ID_BEGIN (bmain, id) {
+    if (ID_IS_OVERRIDE_LIBRARY(id)) {
+      BKE_lib_override_library_id_unused_cleanup(id);
+    }
+  }
+  FOREACH_MAIN_ID_END;
 }
 
 /** Update given override from its reference (re-applying overridden properties). */

source/blender/blenloader/intern/readfile.c

@@ -2762,6 +2762,8 @@ static void direct_link_id_override_property_operation_cb(FileData *fd, void *da
 
   opop->subitem_reference_name = newdataadr(fd, opop->subitem_reference_name);
   opop->subitem_local_name = newdataadr(fd, opop->subitem_local_name);
+
+  opop->tag = 0; /* Runtime only. */
 }
 
 static void direct_link_id_override_property_cb(FileData *fd, void *data)
@@ -2769,6 +2771,9 @@ static void direct_link_id_override_property_cb(FileData *fd, void *data)
   IDOverrideLibraryProperty *op = data;
 
   op->rna_path = newdataadr(fd, op->rna_path);
+
+  op->tag = 0; /* Runtime only. */
+
   link_list_ex(fd, &op->operations, direct_link_id_override_property_operation_cb);
 }
 

source/blender/makesdna/DNA_ID.h

@@ -135,7 +135,10 @@ typedef struct IDOverrideLibraryPropertyOperation {
   /* Type of override. */
   short operation;
   short flag;
-  char _pad0[4];
+
+  /** Runtime, tags are common to both IDOverrideProperty and IDOverridePropertyOperation. */
+  short tag;
+  char _pad0[2];
 
   /* Sub-item references, if needed (for arrays or collections only).
    * We need both reference and local values to allow e.g. insertion into collections
@@ -189,8 +192,18 @@ typedef struct IDOverrideLibraryProperty {
 
   /** List of overriding operations (IDOverridePropertyOperation) applied to this property. */
   ListBase operations;
+
+  /** Runtime, tags are common to both IDOverrideProperty and IDOverridePropertyOperation. */
+  short tag;
+  char _pad0[6];
 } IDOverrideLibraryProperty;
 
+/* IDOverrideProperty->tag and IDOverridePropertyOperation->tag. */
+enum {
+  /** This override property (operation) is unused and should be removed by cleanup process. */
+  IDOVERRIDE_LIBRARY_TAG_UNUSED = 1 << 0,
+};
+
 /* We do not need a full struct for that currently, just a GHash. */
 typedef struct GHash IDOverrideLibraryRuntime;
 

source/blender/makesrna/intern/rna_access_compare_override.c

@@ -677,7 +677,9 @@ bool RNA_struct_override_matches(Main *bmain,
 
     //    printf("Override Checking %s\n", rna_path);
 
-    if (ignore_overridden && BKE_lib_override_library_property_find(override, rna_path) != NULL) {
+    IDOverrideLibraryProperty *op = BKE_lib_override_library_property_find(override, rna_path);
+    if (ignore_overridden && op != NULL) {
+      BKE_lib_override_library_operations_tag(op, IDOVERRIDE_LIBRARY_TAG_UNUSED, false);
       RNA_PATH_FREE;
       continue;
     }
@@ -716,9 +718,13 @@ bool RNA_struct_override_matches(Main *bmain,
 
     if (diff != 0) {
       /* XXX TODO: refine this for per-item overriding of arrays... */
-      IDOverrideLibraryProperty *op = BKE_lib_override_library_property_find(override, rna_path);
+      op = BKE_lib_override_library_property_find(override, rna_path);
       IDOverrideLibraryPropertyOperation *opop = op ? op->operations.first : NULL;
 
+      if (op != NULL) {
+        BKE_lib_override_library_operations_tag(op, IDOVERRIDE_LIBRARY_TAG_UNUSED, false);
+      }
+
       if (do_restore && (report_flags & RNA_OVERRIDE_MATCH_RESULT_CREATED) == 0) {
         /* We are allowed to restore to reference's values. */
         if (ELEM(NULL, op, opop) || opop->operation == IDOVERRIDE_LIBRARY_OP_NOOP) {