Refactor: Move vertex group names to object data

This commit moves the storage of `bDeformGroup` and the active index
to `Mesh`, `Lattice`, and `bGPdata` instead of `Object`. Utility
functions are added to allow easy access to the vertex groups given
an object or an ID.

As explained in T88951, the list of vertex group names is currently
stored separately per object, even though vertex group data is stored
on the geometry. This tends to complicate code and cause bugs,
especially as geometry is created procedurally and tied less closely
to an object.

The "Copy Vertex Groups to Linked" operator is removed, since they
are stored on the geometry anyway.

This patch leaves the object-level python API for vertex groups in
place. Creating a geometry-level RNA API can be a separate step;
the changes in this commit are invasive enough as it is.

Note that opening a file saved in 3.0 in an earlier version means
the vertex groups will not be available.

Differential Revision: https://developer.blender.org/D11689

28 files changed, 228 insertions, 222 deletions

diff --git a/source/blender/editors/armature/armature_skinning.c b/source/blender/editors/armature/armature_skinning.c
index fc9191967f8..ec5c665402b 100644
--- a/source/blender/editors/armature/armature_skinning.c
+++ b/source/blender/editors/armature/armature_skinning.c
@@ -478,7 +478,7 @@ void ED_object_vgroup_calc_from_armature(ReportList *reports,
   bArmature *arm = par->data;
 
   if (mode == ARM_GROUPS_NAME) {
-    const int defbase_tot = BLI_listbase_count(&ob->defbase);
+    const int defbase_tot = BKE_object_defgroup_count(ob);
     int defbase_add;
     /* Traverse the bone list, trying to create empty vertex
      * groups corresponding to the bone.
diff --git a/source/blender/editors/gpencil/gpencil_armature.c b/source/blender/editors/gpencil/gpencil_armature.c
index 24fb0873a86..c800851bb08 100644
--- a/source/blender/editors/gpencil/gpencil_armature.c
+++ b/source/blender/editors/gpencil/gpencil_armature.c
@@ -384,7 +384,7 @@ static void gpencil_add_verts_to_dgroups(
 
           /* loop groups and assign weight */
           for (j = 0; j < numbones; j++) {
-            int def_nr = BLI_findindex(&ob->defbase, dgrouplist[j]);
+            int def_nr = BLI_findindex(&gpd->vertex_group_names, dgrouplist[j]);
             if (def_nr < 0) {
               continue;
             }
@@ -454,7 +454,7 @@ static void gpencil_object_vgroup_calc_from_armature(const bContext *C,
   bArmature *arm = ob_arm->data;
 
   /* always create groups */
-  const int defbase_tot = BLI_listbase_count(&ob->defbase);
+  const int defbase_tot = BKE_object_defgroup_count(ob);
   int defbase_add;
   /* Traverse the bone list, trying to create empty vertex
    * groups corresponding to the bone.
diff --git a/source/blender/editors/gpencil/gpencil_data.c b/source/blender/editors/gpencil/gpencil_data.c
index e272f46d13d..b1e57079d28 100644
--- a/source/blender/editors/gpencil/gpencil_data.c
+++ b/source/blender/editors/gpencil/gpencil_data.c
@@ -2165,7 +2165,9 @@ static bool gpencil_vertex_group_poll(bContext *C)
   Object *ob = CTX_data_active_object(C);
 
   if ((ob) && (ob->type == OB_GPENCIL)) {
-    if (!ID_IS_LINKED(ob) && !ID_IS_LINKED(ob->data) && ob->defbase.first) {
+    const bGPdata *gpd = (const bGPdata *)ob->data;
+    if (!ID_IS_LINKED(ob) && !ID_IS_LINKED(ob->data) &&
+        !BLI_listbase_is_empty(&gpd->vertex_group_names)) {
       if (ELEM(ob->mode, OB_MODE_EDIT_GPENCIL, OB_MODE_SCULPT_GPENCIL)) {
         return true;
       }
@@ -2180,7 +2182,9 @@ static bool gpencil_vertex_group_weight_poll(bContext *C)
   Object *ob = CTX_data_active_object(C);
 
   if ((ob) && (ob->type == OB_GPENCIL)) {
-    if (!ID_IS_LINKED(ob) && !ID_IS_LINKED(ob->data) && ob->defbase.first) {
+    const bGPdata *gpd = (const bGPdata *)ob->data;
+    if (!ID_IS_LINKED(ob) && !ID_IS_LINKED(ob->data) &&
+        !BLI_listbase_is_empty(&gpd->vertex_group_names)) {
       if (ob->mode == OB_MODE_WEIGHT_GPENCIL) {
         return true;
       }
@@ -2333,6 +2337,7 @@ static int gpencil_vertex_group_invert_exec(bContext *C, wmOperator *op)
 {
   ToolSettings *ts = CTX_data_tool_settings(C);
   Object *ob = CTX_data_active_object(C);
+  bGPdata *gpd = ob->data;
 
   /* sanity checks */
   if (ELEM(NULL, ts, ob, ob->data)) {
@@ -2340,8 +2345,9 @@ static int gpencil_vertex_group_invert_exec(bContext *C, wmOperator *op)
   }
 
   MDeformVert *dvert;
-  const int def_nr = ob->actdef - 1;
-  bDeformGroup *defgroup = BLI_findlink(&ob->defbase, def_nr);
+  const int def_nr = gpd->vertex_group_active_index - 1;
+
+  bDeformGroup *defgroup = BLI_findlink(&gpd->vertex_group_names, def_nr);
   if (defgroup == NULL) {
     return OPERATOR_CANCELLED;
   }
@@ -2373,7 +2379,6 @@ static int gpencil_vertex_group_invert_exec(bContext *C, wmOperator *op)
   CTX_DATA_END;
 
   /* notifiers */
-  bGPdata *gpd = ob->data;
   DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_GPENCIL | ND_DATA | NA_EDITED | ND_SPACE_PROPERTIES, NULL);
 
@@ -2403,14 +2408,15 @@ static int gpencil_vertex_group_smooth_exec(bContext *C, wmOperator *op)
 
   ToolSettings *ts = CTX_data_tool_settings(C);
   Object *ob = CTX_data_active_object(C);
+  bGPdata *gpd = ob->data;
 
   /* sanity checks */
   if (ELEM(NULL, ts, ob, ob->data)) {
     return OPERATOR_CANCELLED;
   }
 
-  const int def_nr = ob->actdef - 1;
-  bDeformGroup *defgroup = BLI_findlink(&ob->defbase, def_nr);
+  const int def_nr = gpd->vertex_group_active_index - 1;
+  bDeformGroup *defgroup = BLI_findlink(&gpd->vertex_group_names, def_nr);
   if (defgroup == NULL) {
     return OPERATOR_CANCELLED;
   }
@@ -2470,7 +2476,6 @@ static int gpencil_vertex_group_smooth_exec(bContext *C, wmOperator *op)
   CTX_DATA_END;
 
   /* notifiers */
-  bGPdata *gpd = ob->data;
   DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_GPENCIL | ND_DATA | NA_EDITED | ND_SPACE_PROPERTIES, NULL);
 
@@ -2500,6 +2505,7 @@ static int gpencil_vertex_group_normalize_exec(bContext *C, wmOperator *op)
 {
   ToolSettings *ts = CTX_data_tool_settings(C);
   Object *ob = CTX_data_active_object(C);
+  bGPdata *gpd = ob->data;
 
   /* sanity checks */
   if (ELEM(NULL, ts, ob, ob->data)) {
@@ -2508,8 +2514,8 @@ static int gpencil_vertex_group_normalize_exec(bContext *C, wmOperator *op)
 
   MDeformVert *dvert = NULL;
   MDeformWeight *dw = NULL;
-  const int def_nr = ob->actdef - 1;
-  bDeformGroup *defgroup = BLI_findlink(&ob->defbase, def_nr);
+  const int def_nr = gpd->vertex_group_active_index - 1;
+  bDeformGroup *defgroup = BLI_findlink(&gpd->vertex_group_names, def_nr);
   if (defgroup == NULL) {
     return OPERATOR_CANCELLED;
   }
@@ -2548,7 +2554,6 @@ static int gpencil_vertex_group_normalize_exec(bContext *C, wmOperator *op)
   CTX_DATA_END;
 
   /* notifiers */
-  bGPdata *gpd = ob->data;
   DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_GPENCIL | ND_DATA | NA_EDITED | ND_SPACE_PROPERTIES, NULL);
 
@@ -2576,6 +2581,7 @@ static int gpencil_vertex_group_normalize_all_exec(bContext *C, wmOperator *op)
   ToolSettings *ts = CTX_data_tool_settings(C);
   Object *ob = CTX_data_active_object(C);
   bool lock_active = RNA_boolean_get(op->ptr, "lock_active");
+  bGPdata *gpd = ob->data;
 
   /* sanity checks */
   if (ELEM(NULL, ts, ob, ob->data)) {
@@ -2585,8 +2591,8 @@ static int gpencil_vertex_group_normalize_all_exec(bContext *C, wmOperator *op)
   bDeformGroup *defgroup = NULL;
   MDeformVert *dvert = NULL;
   MDeformWeight *dw = NULL;
-  const int def_nr = ob->actdef - 1;
-  const int defbase_tot = BLI_listbase_count(&ob->defbase);
+  const int def_nr = gpd->vertex_group_active_index - 1;
+  const int defbase_tot = BLI_listbase_count(&gpd->vertex_group_names);
   if (defbase_tot == 0) {
     return OPERATOR_CANCELLED;
   }
@@ -2603,7 +2609,7 @@ static int gpencil_vertex_group_normalize_all_exec(bContext *C, wmOperator *op)
     for (int i = 0; i < gps->totpoints; i++) {
       dvert = &gps->dvert[i];
       for (int v = 0; v < defbase_tot; v++) {
-        defgroup = BLI_findlink(&ob->defbase, v);
+        defgroup = BLI_findlink(&gpd->vertex_group_names, v);
         /* skip NULL or locked groups */
         if ((defgroup == NULL) || (defgroup->flag & DG_LOCK_WEIGHT)) {
           continue;
@@ -2629,7 +2635,7 @@ static int gpencil_vertex_group_normalize_all_exec(bContext *C, wmOperator *op)
 
       dvert = &gps->dvert[i];
       for (int v = 0; v < defbase_tot; v++) {
-        defgroup = BLI_findlink(&ob->defbase, v);
+        defgroup = BLI_findlink(&gpd->vertex_group_names, v);
         /* skip NULL or locked groups */
         if ((defgroup == NULL) || (defgroup->flag & DG_LOCK_WEIGHT)) {
           continue;
@@ -2653,7 +2659,6 @@ static int gpencil_vertex_group_normalize_all_exec(bContext *C, wmOperator *op)
   CTX_DATA_END;
 
   /* notifiers */
-  bGPdata *gpd = ob->data;
   DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_GPENCIL | ND_DATA | NA_EDITED | ND_SPACE_PROPERTIES, NULL);
 
@@ -2769,7 +2774,6 @@ int ED_gpencil_join_objects_exec(bContext *C, wmOperator *op)
   Scene *scene = CTX_data_scene(C);
   Depsgraph *depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
   Object *ob_active = CTX_data_active_object(C);
-  bGPdata *gpd_dst = NULL;
   bool ok = false;
 
   /* Ensure we're in right mode and that the active object is correct */
@@ -2807,7 +2811,7 @@ int ED_gpencil_join_objects_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
 
-  gpd_dst = ob_active->data;
+  bGPdata *gpd_dst = ob_active->data;
   Object *ob_dst = ob_active;
 
   /* loop and join all data */
@@ -2828,11 +2832,11 @@ int ED_gpencil_join_objects_exec(bContext *C, wmOperator *op)
 
         /* copy vertex groups to the base one's */
         int old_idx = 0;
-        LISTBASE_FOREACH (bDeformGroup *, dg, &ob_iter->defbase) {
+        LISTBASE_FOREACH (bDeformGroup *, dg, &gpd_src->vertex_group_names) {
           bDeformGroup *vgroup = MEM_dupallocN(dg);
-          int idx = BLI_listbase_count(&ob_active->defbase);
+          int idx = BLI_listbase_count(&gpd_dst->vertex_group_names);
           BKE_object_defgroup_unique_name(vgroup, ob_active);
-          BLI_addtail(&ob_active->defbase, vgroup);
+          BLI_addtail(&gpd_dst->vertex_group_names, vgroup);
           /* update vertex groups in strokes in original data */
           LISTBASE_FOREACH (bGPDlayer *, gpl_src, &gpd->layers) {
             LISTBASE_FOREACH (bGPDframe *, gpf, &gpl_src->frames) {
@@ -2852,8 +2856,9 @@ int ED_gpencil_join_objects_exec(bContext *C, wmOperator *op)
           }
           old_idx++;
         }
-        if (ob_active->defbase.first && ob_active->actdef == 0) {
-          ob_active->actdef = 1;
+        if (!BLI_listbase_is_empty(&gpd_dst->vertex_group_names) &&
+            gpd_dst->vertex_group_active_index == 0) {
+          gpd_dst->vertex_group_active_index = 1;
         }
 
         /* add missing materials reading source materials and checking in destination object */
diff --git a/source/blender/editors/gpencil/gpencil_fill.c b/source/blender/editors/gpencil/gpencil_fill.c
index 091ff2c16b0..67e1bd5294b 100644
--- a/source/blender/editors/gpencil/gpencil_fill.c
+++ b/source/blender/editors/gpencil/gpencil_fill.c
@@ -1522,8 +1522,8 @@ static void gpencil_stroke_from_buffer(tGPDfill *tgpf)
   pt = gps->points;
   point2D = (tGPspoint *)tgpf->sbuffer;
 
-  const int def_nr = tgpf->ob->actdef - 1;
-  const bool have_weight = (bool)BLI_findlink(&tgpf->ob->defbase, def_nr);
+  const int def_nr = tgpf->gpd->vertex_group_active_index - 1;
+  const bool have_weight = (bool)BLI_findlink(&tgpf->gpd->vertex_group_names, def_nr);
 
   if ((ts->gpencil_flags & GP_TOOL_FLAG_CREATE_WEIGHTS) && (have_weight)) {
     BKE_gpencil_dvert_ensure(gps);
diff --git a/source/blender/editors/gpencil/gpencil_paint.c b/source/blender/editors/gpencil/gpencil_paint.c
index 67d4b7726b5..d6f6dbb2b10 100644
--- a/source/blender/editors/gpencil/gpencil_paint.c
+++ b/source/blender/editors/gpencil/gpencil_paint.c
@@ -938,8 +938,8 @@ static void gpencil_stroke_newfrombuffer(tGPsdata *p)
   Depsgraph *depsgraph = p->depsgraph;
   Object *obact = (Object *)p->ownerPtr.data;
   RegionView3D *rv3d = p->region->regiondata;
-  const int def_nr = obact->actdef - 1;
-  const bool have_weight = (bool)BLI_findlink(&obact->defbase, def_nr);
+  const int def_nr = gpd->vertex_group_active_index - 1;
+  const bool have_weight = (bool)BLI_findlink(&gpd->vertex_group_names, def_nr);
   const char align_flag = ts->gpencil_v3d_align;
   const bool is_depth = (bool)(align_flag & (GP_PROJECT_DEPTH_VIEW | GP_PROJECT_DEPTH_STROKE));
   const bool is_lock_axis_view = (bool)(ts->gp_sculpt.lock_axis == 0);
diff --git a/source/blender/editors/gpencil/gpencil_primitive.c b/source/blender/editors/gpencil/gpencil_primitive.c
index a2b4e5dee64..78eaab01b1a 100644
--- a/source/blender/editors/gpencil/gpencil_primitive.c
+++ b/source/blender/editors/gpencil/gpencil_primitive.c
@@ -1315,8 +1315,9 @@ static void gpencil_primitive_interaction_end(bContext *C,
   Brush *brush = tgpi->brush;
   BrushGpencilSettings *brush_settings = brush->gpencil_settings;
 
-  const int def_nr = tgpi->ob->actdef - 1;
-  const bool have_weight = (bool)BLI_findlink(&tgpi->ob->defbase, def_nr);
+  const int def_nr = tgpi->gpd->vertex_group_active_index - 1;
+  const ListBase *defbase = BKE_object_defgroup_list(tgpi->ob);
+  const bool have_weight = (bool)BLI_findlink(defbase, def_nr);
 
   /* return to normal cursor and header status */
   ED_workspace_status_text(C, NULL);
diff --git a/source/blender/editors/gpencil/gpencil_sculpt_paint.c b/source/blender/editors/gpencil/gpencil_sculpt_paint.c
index efd0f86df03..462462cf341 100644
--- a/source/blender/editors/gpencil/gpencil_sculpt_paint.c
+++ b/source/blender/editors/gpencil/gpencil_sculpt_paint.c
@@ -1177,8 +1177,8 @@ static bool gpencil_sculpt_brush_init(bContext *C, wmOperator *op)
   gso->object = ob;
   if (ob) {
     invert_m4_m4(gso->inv_mat, ob->obmat);
-    gso->vrgroup = ob->actdef - 1;
-    if (!BLI_findlink(&ob->defbase, gso->vrgroup)) {
+    gso->vrgroup = gso->gpd->vertex_group_active_index - 1;
+    if (!BLI_findlink(&gso->gpd->vertex_group_names, gso->vrgroup)) {
       gso->vrgroup = -1;
     }
     /* Check if some modifier can transform the stroke. */
diff --git a/source/blender/editors/gpencil/gpencil_utils.c b/source/blender/editors/gpencil/gpencil_utils.c
index e6488cfe454..ba3d3b584d7 100644
--- a/source/blender/editors/gpencil/gpencil_utils.c
+++ b/source/blender/editors/gpencil/gpencil_utils.c
@@ -1600,8 +1600,8 @@ void ED_gpencil_vgroup_assign(bContext *C, Object *ob, float weight)
 {
   bGPdata *gpd = (bGPdata *)ob->data;
   const bool is_multiedit = (bool)GPENCIL_MULTIEDIT_SESSIONS_ON(gpd);
-  const int def_nr = ob->actdef - 1;
-  if (!BLI_findlink(&ob->defbase, def_nr)) {
+  const int def_nr = gpd->vertex_group_active_index - 1;
+  if (!BLI_findlink(&gpd->vertex_group_names, def_nr)) {
     return;
   }
 
@@ -1654,8 +1654,8 @@ void ED_gpencil_vgroup_remove(bContext *C, Object *ob)
 {
   bGPdata *gpd = (bGPdata *)ob->data;
   const bool is_multiedit = (bool)GPENCIL_MULTIEDIT_SESSIONS_ON(gpd);
-  const int def_nr = ob->actdef - 1;
-  if (!BLI_findlink(&ob->defbase, def_nr)) {
+  const int def_nr = gpd->vertex_group_active_index - 1;
+  if (!BLI_findlink(&gpd->vertex_group_names, def_nr)) {
     return;
   }
 
@@ -1707,8 +1707,8 @@ void ED_gpencil_vgroup_select(bContext *C, Object *ob)
 {
   bGPdata *gpd = (bGPdata *)ob->data;
   const bool is_multiedit = (bool)GPENCIL_MULTIEDIT_SESSIONS_ON(gpd);
-  const int def_nr = ob->actdef - 1;
-  if (!BLI_findlink(&ob->defbase, def_nr)) {
+  const int def_nr = gpd->vertex_group_active_index - 1;
+  if (!BLI_findlink(&gpd->vertex_group_names, def_nr)) {
     return;
   }
 
@@ -1762,8 +1762,8 @@ void ED_gpencil_vgroup_deselect(bContext *C, Object *ob)
 {
   bGPdata *gpd = (bGPdata *)ob->data;
   const bool is_multiedit = (bool)GPENCIL_MULTIEDIT_SESSIONS_ON(gpd);
-  const int def_nr = ob->actdef - 1;
-  if (!BLI_findlink(&ob->defbase, def_nr)) {
+  const int def_nr = gpd->vertex_group_active_index - 1;
+  if (!BLI_findlink(&gpd->vertex_group_names, def_nr)) {
     return;
   }
 
diff --git a/source/blender/editors/gpencil/gpencil_weight_paint.c b/source/blender/editors/gpencil/gpencil_weight_paint.c
index 6d953a4d8cf..d14322e12b5 100644
--- a/source/blender/editors/gpencil/gpencil_weight_paint.c
+++ b/source/blender/editors/gpencil/gpencil_weight_paint.c
@@ -252,7 +252,7 @@ static bool brush_draw_apply(tGP_BrushWeightpaintData *gso,
     }
   }
   else {
-    bDeformGroup *defgroup = BLI_findlink(&gso->object->defbase, gso->vrgroup);
+    bDeformGroup *defgroup = BLI_findlink(&gso->gpd->vertex_group_names, gso->vrgroup);
     if (defgroup->flag & DG_LOCK_WEIGHT) {
       return false;
     }
@@ -308,8 +308,8 @@ static bool gpencil_weightpaint_brush_init(bContext *C, wmOperator *op)
   gso->scene = scene;
   gso->object = ob;
   if (ob) {
-    gso->vrgroup = ob->actdef - 1;
-    if (!BLI_findlink(&ob->defbase, gso->vrgroup)) {
+    gso->vrgroup = gso->gpd->vertex_group_active_index - 1;
+    if (!BLI_findlink(&gso->gpd->vertex_group_names, gso->vrgroup)) {
       gso->vrgroup = -1;
     }
   }
diff --git a/source/blender/editors/lattice/editlattice_select.c b/source/blender/editors/lattice/editlattice_select.c
index e73a02840c9..e6f190f335b 100644
--- a/source/blender/editors/lattice/editlattice_select.c
+++ b/source/blender/editors/lattice/editlattice_select.c
@@ -514,7 +514,7 @@ static int lattice_select_ungrouped_exec(bContext *C, wmOperator *op)
     BPoint *bp;
     int a, tot;
 
-    if (BLI_listbase_is_empty(&obedit->defbase) || lt->dvert == NULL) {
+    if (BLI_listbase_is_empty(&lt->vertex_group_names) || lt->dvert == NULL) {
       continue;
     }
 
diff --git a/source/blender/editors/mesh/editmesh_select.c b/source/blender/editors/mesh/editmesh_select.c
index 3304a1c8683..830c9abb41e 100644
--- a/source/blender/editors/mesh/editmesh_select.c
+++ b/source/blender/editors/mesh/editmesh_select.c
@@ -36,6 +36,7 @@
 
 #include "BKE_context.h"
 #include "BKE_customdata.h"
+#include "BKE_deform.h"
 #include "BKE_editmesh.h"
 #include "BKE_layer.h"
 #include "BKE_report.h"
@@ -4740,10 +4741,11 @@ static bool edbm_select_ungrouped_poll(bContext *C)
     BMEditMesh *em = BKE_editmesh_from_object(obedit);
     const int cd_dvert_offset = CustomData_get_offset(&em->bm->vdata, CD_MDEFORMVERT);
 
+    const ListBase *defbase = BKE_object_defgroup_list(obedit);
     if ((em->selectmode & SCE_SELECT_VERTEX) == 0) {
       CTX_wm_operator_poll_msg_set(C, "Must be in vertex selection mode");
     }
-    else if (BLI_listbase_is_empty(&obedit->defbase) || cd_dvert_offset == -1) {
+    else if (BLI_listbase_is_empty(defbase) || cd_dvert_offset == -1) {
       CTX_wm_operator_poll_msg_set(C, "No weights/vertex groups on object");
     }
     else {
diff --git a/source/blender/editors/mesh/editmesh_select_similar.c b/source/blender/editors/mesh/editmesh_select_similar.c
index c48e0fdc52b..c452f7a7487 100644
--- a/source/blender/editors/mesh/editmesh_select_similar.c
+++ b/source/blender/editors/mesh/editmesh_select_similar.c
@@ -30,6 +30,7 @@
 
 #include "BKE_context.h"
 #include "BKE_customdata.h"
+#include "BKE_deform.h"
 #include "BKE_editmesh.h"
 #include "BKE_layer.h"
 #include "BKE_material.h"
@@ -1042,7 +1043,7 @@ static int similar_vert_select_exec(bContext *C, wmOperator *op)
       if (cd_dvert_offset == -1) {
         continue;
       }
-      defbase_len = BLI_listbase_count(&ob->defbase);
+      defbase_len = BKE_object_defgroup_count(ob);
       if (defbase_len == 0) {
         continue;
       }
@@ -1091,8 +1092,10 @@ static int similar_vert_select_exec(bContext *C, wmOperator *op)
       /* We store the names of the vertex groups, so we can select
        * vertex groups with the same name in different objects. */
 
+      const ListBase *defbase = BKE_object_defgroup_list(ob);
+
       int i = 0;
-      LISTBASE_FOREACH (bDeformGroup *, dg, &ob->defbase) {
+      LISTBASE_FOREACH (bDeformGroup *, dg, defbase) {
         if (BLI_BITMAP_TEST(defbase_selected, i)) {
           BLI_gset_add(gset, dg->name);
         }
@@ -1129,7 +1132,8 @@ static int similar_vert_select_exec(bContext *C, wmOperator *op)
       if (cd_dvert_offset == -1) {
         continue;
       }
-      defbase_len = BLI_listbase_count(&ob->defbase);
+      const ListBase *defbase = BKE_object_defgroup_list(ob);
+      defbase_len = BLI_listbase_count(defbase);
       if (defbase_len == 0) {
         continue;
       }
@@ -1142,7 +1146,7 @@ static int similar_vert_select_exec(bContext *C, wmOperator *op)
       GSetIterator gs_iter;
       GSET_ITER (gs_iter, gset) {
         const char *name = BLI_gsetIterator_getKey(&gs_iter);
-        int vgroup_id = BLI_findstringindex(&ob->defbase, name, offsetof(bDeformGroup, name));
+        int vgroup_id = BLI_findstringindex(defbase, name, offsetof(bDeformGroup, name));
         if (vgroup_id != -1) {
           BLI_BITMAP_ENABLE(defbase_selected, vgroup_id);
           found_any = true;
diff --git a/source/blender/editors/mesh/editmesh_tools.c b/source/blender/editors/mesh/editmesh_tools.c
index eca8adeba34..41a9f426798 100644
--- a/source/blender/editors/mesh/editmesh_tools.c
+++ b/source/blender/editors/mesh/editmesh_tools.c
@@ -5740,7 +5740,7 @@ static int edbm_decimate_exec(bContext *C, wmOperator *op)
     float *vweights = MEM_mallocN(sizeof(*vweights) * bm->totvert, __func__);
     {
       const int cd_dvert_offset = CustomData_get_offset(&bm->vdata, CD_MDEFORMVERT);
-      const int defbase_act = obedit->actdef - 1;
+      const int defbase_act = BKE_object_defgroup_active_index_get(obedit) - 1;
 
       if (use_vertex_group && (cd_dvert_offset == -1)) {
         BKE_report(op->reports, RPT_WARNING, "No active vertex group");
diff --git a/source/blender/editors/mesh/meshtools.c b/source/blender/editors/mesh/meshtools.c
index ca68c47cf8e..27fb21e1dfb 100644
--- a/source/blender/editors/mesh/meshtools.c
+++ b/source/blender/editors/mesh/meshtools.c
@@ -475,16 +475,17 @@ int ED_mesh_join_objects_exec(bContext *C, wmOperator *op)
       me = ob_iter->data;
 
       /* Join this object's vertex groups to the base one's */
-      for (dg = ob_iter->defbase.first; dg; dg = dg->next) {
+      for (dg = me->vertex_group_names.first; dg; dg = dg->next) {
         /* See if this group exists in the object (if it doesn't, add it to the end) */
         if (!BKE_object_defgroup_find_name(ob, dg->name)) {
           odg = MEM_mallocN(sizeof(bDeformGroup), "join deformGroup");
           memcpy(odg, dg, sizeof(bDeformGroup));
-          BLI_addtail(&ob->defbase, odg);
+          BLI_addtail(&mesh_active->vertex_group_names, odg);
         }
       }
-      if (ob->defbase.first && ob->actdef == 0) {
-        ob->actdef = 1;
+      if (!BLI_listbase_is_empty(&mesh_active->vertex_group_names) &&
+          me->vertex_group_active_index == 0) {
+        me->vertex_group_active_index = 1;
       }
 
       /* Join this object's face maps to the base one's. */
@@ -1473,19 +1474,21 @@ bool ED_mesh_pick_vert(
 
 MDeformVert *ED_mesh_active_dvert_get_em(Object *ob, BMVert **r_eve)
 {
-  if (ob->mode & OB_MODE_EDIT && ob->type == OB_MESH && ob->defbase.first) {
+  if (ob->mode & OB_MODE_EDIT && ob->type == OB_MESH) {
     Mesh *me = ob->data;
-    BMesh *bm = me->edit_mesh->bm;
-    const int cd_dvert_offset = CustomData_get_offset(&bm->vdata, CD_MDEFORMVERT);
+    if (!BLI_listbase_is_empty(&me->vertex_group_names)) {
+      BMesh *bm = me->edit_mesh->bm;
+      const int cd_dvert_offset = CustomData_get_offset(&bm->vdata, CD_MDEFORMVERT);
 
-    if (cd_dvert_offset != -1) {
-      BMVert *eve = BM_mesh_active_vert_get(bm);
+      if (cd_dvert_offset != -1) {
+        BMVert *eve = BM_mesh_active_vert_get(bm);
 
-      if (eve) {
-        if (r_eve) {
-          *r_eve = eve;
+        if (eve) {
+          if (r_eve) {
+            *r_eve = eve;
+          }
+          return BM_ELEM_CD_GET_VOID_P(eve, cd_dvert_offset);
         }
-        return BM_ELEM_CD_GET_VOID_P(eve, cd_dvert_offset);
       }
     }
   }
diff --git a/source/blender/editors/object/object_data_transfer.c b/source/blender/editors/object/object_data_transfer.c
index 742c7abb7ff..2109fe2a822 100644
--- a/source/blender/editors/object/object_data_transfer.c
+++ b/source/blender/editors/object/object_data_transfer.c
@@ -33,6 +33,7 @@
 
 #include "BKE_context.h"
 #include "BKE_data_transfer.h"
+#include "BKE_deform.h"
 #include "BKE_mesh_mapping.h"
 #include "BKE_mesh_remap.h"
 #include "BKE_mesh_runtime.h"
@@ -133,12 +134,13 @@ static const EnumPropertyItem *dt_layers_select_src_itemf(bContext *C,
     }
 
     if (ob_src) {
-      bDeformGroup *dg;
+      const bDeformGroup *dg;
       int i;
 
       RNA_enum_item_add_separator(&item, &totitem);
 
-      for (i = 0, dg = ob_src->defbase.first; dg; i++, dg = dg->next) {
+      const ListBase *defbase = BKE_object_defgroup_list(ob_src);
+      for (i = 0, dg = defbase->first; dg; i++, dg = dg->next) {
         tmp_item.value = i;
         tmp_item.identifier = tmp_item.name = dg->name;
         RNA_enum_item_add(&item, &totitem, &tmp_item);
diff --git a/source/blender/editors/object/object_hook.c b/source/blender/editors/object/object_hook.c
index fcee2818b22..5065a2c00f0 100644
--- a/source/blender/editors/object/object_hook.c
+++ b/source/blender/editors/object/object_hook.c
@@ -105,14 +105,13 @@ static int return_editmesh_indexar(BMEditMesh *em, int *r_tot, int **r_indexar,
 
 static bool return_editmesh_vgroup(Object *obedit, BMEditMesh *em, char *r_name, float r_cent[3])
 {
-  const int cd_dvert_offset = obedit->actdef ?
+  const int active_index = BKE_object_defgroup_active_index_get(obedit);
+  const int cd_dvert_offset = active_index ?
                                   CustomData_get_offset(&em->bm->vdata, CD_MDEFORMVERT) :
                                   -1;
 
-  zero_v3(r_cent);
-
   if (cd_dvert_offset != -1) {
-    const int defgrp_index = obedit->actdef - 1;
+    const int defgrp_index = active_index - 1;
     int totvert = 0;
 
     MDeformVert *dvert;
@@ -129,7 +128,8 @@ static bool return_editmesh_vgroup(Object *obedit, BMEditMesh *em, char *r_name,
       }
     }
     if (totvert) {
-      bDeformGroup *dg = BLI_findlink(&obedit->defbase, defgrp_index);
+      const ListBase *defbase = BKE_object_defgroup_list(obedit);
+      bDeformGroup *dg = BLI_findlink(defbase, defgrp_index);
       BLI_strncpy(r_name, dg->name, sizeof(dg->name));
       mul_v3_fl(r_cent, 1.0f / (float)totvert);
       return true;
diff --git a/source/blender/editors/object/object_intern.h b/source/blender/editors/object/object_intern.h
index 5bf04e195fe..5a3a28b5a3f 100644
--- a/source/blender/editors/object/object_intern.h
+++ b/source/blender/editors/object/object_intern.h
@@ -247,7 +247,6 @@ void OBJECT_OT_vertex_group_assign_new(struct wmOperatorType *ot);
 void OBJECT_OT_vertex_group_remove_from(struct wmOperatorType *ot);
 void OBJECT_OT_vertex_group_select(struct wmOperatorType *ot);
 void OBJECT_OT_vertex_group_deselect(struct wmOperatorType *ot);
-void OBJECT_OT_vertex_group_copy_to_linked(struct wmOperatorType *ot);
 void OBJECT_OT_vertex_group_copy_to_selected(struct wmOperatorType *ot);
 void OBJECT_OT_vertex_group_copy(struct wmOperatorType *ot);
 void OBJECT_OT_vertex_group_normalize(struct wmOperatorType *ot);
diff --git a/source/blender/editors/object/object_ops.c b/source/blender/editors/object/object_ops.c
index dc60d4df7d1..a438c760d3b 100644
--- a/source/blender/editors/object/object_ops.c
+++ b/source/blender/editors/object/object_ops.c
@@ -201,7 +201,6 @@ void ED_operatortypes_object(void)
   WM_operatortype_append(OBJECT_OT_vertex_group_remove_from);
   WM_operatortype_append(OBJECT_OT_vertex_group_select);
   WM_operatortype_append(OBJECT_OT_vertex_group_deselect);
-  WM_operatortype_append(OBJECT_OT_vertex_group_copy_to_linked);
   WM_operatortype_append(OBJECT_OT_vertex_group_copy_to_selected);
   WM_operatortype_append(OBJECT_OT_vertex_group_copy);
   WM_operatortype_append(OBJECT_OT_vertex_group_normalize);
diff --git a/source/blender/editors/object/object_vgroup.c b/source/blender/editors/object/object_vgroup.c
index 37075a29b92..4ea599fd30e 100644
--- a/source/blender/editors/object/object_vgroup.c
+++ b/source/blender/editors/object/object_vgroup.c
@@ -130,7 +130,7 @@ bool ED_vgroup_sync_from_pose(Object *ob)
     if (arm->act_bone) {
       int def_num = BKE_object_defgroup_name_index(ob, arm->act_bone->name);
       if (def_num != -1) {
-        ob->actdef = def_num + 1;
+        BKE_object_defgroup_active_index_set(ob, def_num + 1);
         return true;
       }
     }
@@ -389,11 +389,16 @@ bool ED_vgroup_array_copy(Object *ob, Object *ob_from)
   int dvert_tot_from;
   int dvert_tot;
   int i;
-  int defbase_tot_from = BLI_listbase_count(&ob_from->defbase);
-  int defbase_tot = BLI_listbase_count(&ob->defbase);
+  ListBase *defbase_dst = BKE_object_defgroup_list_mutable(ob);
+  const ListBase *defbase_src = BKE_object_defgroup_list(ob_from);
+
+  int defbase_tot_from = BLI_listbase_count(defbase_src);
+  int defbase_tot = BLI_listbase_count(defbase_dst);
   bool new_vgroup = false;
 
-  if (ob == ob_from) {
+  BLI_assert(ob != ob_from);
+
+  if (ob->data == ob_from->data) {
     return true;
   }
 
@@ -429,9 +434,9 @@ bool ED_vgroup_array_copy(Object *ob, Object *ob_from)
   }
 
   /* do the copy */
-  BLI_freelistN(&ob->defbase);
-  BLI_duplicatelist(&ob->defbase, &ob_from->defbase);
-  ob->actdef = ob_from->actdef;
+  BLI_freelistN(defbase_dst);
+  BLI_duplicatelist(defbase_dst, defbase_src);
+  BKE_object_defgroup_active_index_set(ob, BKE_object_defgroup_active_index_get(ob_from));
 
   if (defbase_tot_from < defbase_tot) {
     /* correct vgroup indices because the number of vgroups is being reduced. */
@@ -882,7 +887,8 @@ void ED_vgroup_vert_add(Object *ob, bDeformGroup *dg, int vertnum, float weight,
   /* add the vert to the deform group with the
    * specified assign mode
    */
-  const int def_nr = BLI_findindex(&ob->defbase, dg);
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  const int def_nr = BLI_findindex(defbase, dg);
 
   MDeformVert *dv = NULL;
   int tot;
@@ -913,7 +919,8 @@ void ED_vgroup_vert_remove(Object *ob, bDeformGroup *dg, int vertnum)
 
   /* TODO(campbell): This is slow in a loop, better pass def_nr directly,
    * but leave for later. */
-  const int def_nr = BLI_findindex(&ob->defbase, dg);
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  const int def_nr = BLI_findindex(defbase, dg);
 
   if (def_nr != -1) {
     MDeformVert *dvert = NULL;
@@ -989,7 +996,8 @@ static float get_vert_def_nr(Object *ob, const int def_nr, const int vertnum)
 
 float ED_vgroup_vert_weight(Object *ob, bDeformGroup *dg, int vertnum)
 {
-  const int def_nr = BLI_findindex(&ob->defbase, dg);
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  const int def_nr = BLI_findindex(defbase, dg);
 
   if (def_nr == -1) {
     return -1;
@@ -1000,9 +1008,9 @@ float ED_vgroup_vert_weight(Object *ob, bDeformGroup *dg, int vertnum)
 
 void ED_vgroup_select_by_name(Object *ob, const char *name)
 {
-  /* NOTE: ob->actdef==0 signals on painting to create a new one,
+  /* NOTE: actdef==0 signals on painting to create a new one,
    * if a bone in posemode is selected */
-  ob->actdef = BKE_object_defgroup_name_index(ob, name) + 1;
+  BKE_object_defgroup_active_index_set(ob, BKE_object_defgroup_name_index(ob, name) + 1);
 }
 
 /** \} */
@@ -1014,9 +1022,10 @@ void ED_vgroup_select_by_name(Object *ob, const char *name)
 /* only in editmode */
 static void vgroup_select_verts(Object *ob, int select)
 {
-  const int def_nr = ob->actdef - 1;
+  const int def_nr = BKE_object_defgroup_active_index_get(ob) - 1;
 
-  if (!BLI_findlink(&ob->defbase, def_nr)) {
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  if (!BLI_findlink(defbase, def_nr)) {
     return;
   }
 
@@ -1111,7 +1120,9 @@ static void vgroup_duplicate(Object *ob)
   MDeformVert **dvert_array = NULL;
   int i, idg, icdg, dvert_tot = 0;
 
-  dg = BLI_findlink(&ob->defbase, (ob->actdef - 1));
+  ListBase *defbase = BKE_object_defgroup_list_mutable(ob);
+
+  dg = BLI_findlink(defbase, BKE_object_defgroup_active_index_get(ob) - 1);
   if (!dg) {
     return;
   }
@@ -1127,11 +1138,11 @@ static void vgroup_duplicate(Object *ob)
   BLI_strncpy(cdg->name, name, sizeof(cdg->name));
   BKE_object_defgroup_unique_name(cdg, ob);
 
-  BLI_addtail(&ob->defbase, cdg);
+  BLI_addtail(defbase, cdg);
 
-  idg = (ob->actdef - 1);
-  ob->actdef = BLI_listbase_count(&ob->defbase);
-  icdg = (ob->actdef - 1);
+  idg = BKE_object_defgroup_active_index_get(ob) - 1;
+  BKE_object_defgroup_active_index_set(ob, BLI_listbase_count(defbase));
+  icdg = BKE_object_defgroup_active_index_get(ob) - 1;
 
   /* TODO(campbell): we might want to allow only copy selected verts here? */
   ED_vgroup_parray_alloc(ob->data, &dvert_array, &dvert_tot, false);
@@ -1157,11 +1168,12 @@ static bool vgroup_normalize(Object *ob)
   MDeformWeight *dw;
   MDeformVert *dv, **dvert_array = NULL;
   int dvert_tot = 0;
-  const int def_nr = ob->actdef - 1;
+  const int def_nr = BKE_object_defgroup_active_index_get(ob) - 1;
 
   const bool use_vert_sel = vertex_group_use_vert_sel(ob);
 
-  if (!BLI_findlink(&ob->defbase, def_nr)) {
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  if (!BLI_findlink(defbase, def_nr)) {
     return false;
   }
 
@@ -1639,7 +1651,7 @@ static bool vgroup_normalize_all(Object *ob,
 {
   MDeformVert *dv, **dvert_array = NULL;
   int i, dvert_tot = 0;
-  const int def_nr = ob->actdef - 1;
+  const int def_nr = BKE_object_defgroup_active_index_get(ob) - 1;
 
   const bool use_vert_sel = vertex_group_use_vert_sel(ob);
 
@@ -1651,7 +1663,8 @@ static bool vgroup_normalize_all(Object *ob,
   ED_vgroup_parray_alloc(ob->data, &dvert_array, &dvert_tot, use_vert_sel);
 
   if (dvert_array) {
-    const int defbase_tot = BLI_listbase_count(&ob->defbase);
+    const ListBase *defbase = BKE_object_defgroup_list(ob);
+    const int defbase_tot = BLI_listbase_count(defbase);
     bool *lock_flags = BKE_object_defgroup_lock_flags_get(ob, defbase_tot);
     bool changed = false;
 
@@ -1742,7 +1755,7 @@ static const EnumPropertyItem vgroup_lock_mask[] = {
 
 static bool *vgroup_selected_get(Object *ob)
 {
-  int sel_count = 0, defbase_tot = BLI_listbase_count(&ob->defbase);
+  int sel_count = 0, defbase_tot = BKE_object_defgroup_count(ob);
   bool *mask;
 
   if (ob->mode & OB_MODE_WEIGHT_PAINT) {
@@ -1759,8 +1772,9 @@ static bool *vgroup_selected_get(Object *ob)
     mask = MEM_callocN(defbase_tot * sizeof(bool), __func__);
   }
 
-  if (sel_count == 0 && ob->actdef >= 1 && ob->actdef <= defbase_tot) {
-    mask[ob->actdef - 1] = true;
+  const int actdef = BKE_object_defgroup_active_index_get(ob);
+  if (sel_count == 0 && actdef >= 1 && actdef <= defbase_tot) {
+    mask[actdef - 1] = true;
   }
 
   return mask;
@@ -1775,11 +1789,12 @@ static void vgroup_lock_all(Object *ob, int action, int mask)
   if (mask != VGROUP_MASK_ALL) {
     selected = vgroup_selected_get(ob);
   }
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
 
   if (action == VGROUP_TOGGLE) {
     action = VGROUP_LOCK;
 
-    for (dg = ob->defbase.first, i = 0; dg; dg = dg->next, i++) {
+    for (dg = defbase->first, i = 0; dg; dg = dg->next, i++) {
       switch (mask) {
         case VGROUP_MASK_INVERT_UNSELECTED:
         case VGROUP_MASK_SELECTED:
@@ -1802,7 +1817,7 @@ static void vgroup_lock_all(Object *ob, int action, int mask)
     }
   }
 
-  for (dg = ob->defbase.first, i = 0; dg; dg = dg->next, i++) {
+  for (dg = defbase->first, i = 0; dg; dg = dg->next, i++) {
     switch (mask) {
       case VGROUP_MASK_SELECTED:
         if (!selected[i]) {
@@ -2379,13 +2394,15 @@ void ED_vgroup_mirror(Object *ob,
   MDeformVert *dvert, *dvert_mirr;
   char sel, sel_mirr;
   int *flip_map = NULL, flip_map_len;
-  const int def_nr = ob->actdef - 1;
+  const int def_nr = BKE_object_defgroup_active_index_get(ob) - 1;
   int totmirr = 0, totfail = 0;
 
   *r_totmirr = *r_totfail = 0;
 
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+
   if ((mirror_weights == false && flip_vgroups == false) ||
-      (BLI_findlink(&ob->defbase, def_nr) == NULL)) {
+      (BLI_findlink(defbase, def_nr) == NULL)) {
     return;
   }
 
@@ -2569,7 +2586,8 @@ cleanup:
 
 static void vgroup_delete_active(Object *ob)
 {
-  bDeformGroup *dg = BLI_findlink(&ob->defbase, ob->actdef - 1);
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  bDeformGroup *dg = BLI_findlink(defbase, BKE_object_defgroup_active_index_get(ob) - 1);
   if (!dg) {
     return;
   }
@@ -2580,9 +2598,10 @@ static void vgroup_delete_active(Object *ob)
 /* only in editmode */
 static void vgroup_assign_verts(Object *ob, const float weight)
 {
-  const int def_nr = ob->actdef - 1;
+  const int def_nr = BKE_object_defgroup_active_index_get(ob) - 1;
 
-  if (!BLI_findlink(&ob->defbase, def_nr)) {
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  if (!BLI_findlink(defbase, def_nr)) {
     return;
   }
 
@@ -2700,7 +2719,8 @@ static bool vertex_group_poll_ex(bContext *C, Object *ob)
     return false;
   }
 
-  if (BLI_listbase_is_empty(&ob->defbase)) {
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  if (BLI_listbase_is_empty(defbase)) {
     CTX_wm_operator_poll_msg_set(C, "Object has no vertex groups");
     return false;
   }
@@ -2823,8 +2843,10 @@ static bool vertex_group_vert_select_unlocked_poll(bContext *C)
     return false;
   }
 
-  if (ob->actdef != 0) {
-    bDeformGroup *dg = BLI_findlink(&ob->defbase, ob->actdef - 1);
+  const int def_nr = BKE_object_defgroup_active_index_get(ob);
+  if (def_nr != 0) {
+    const ListBase *defbase = BKE_object_defgroup_list(ob);
+    const bDeformGroup *dg = BLI_findlink(defbase, def_nr - 1);
     if (dg) {
       return !(dg->flag & DG_LOCK_WEIGHT);
     }
@@ -3025,8 +3047,8 @@ static int vertex_group_remove_from_exec(bContext *C, wmOperator *op)
     }
   }
   else {
-    bDeformGroup *dg = BLI_findlink(&ob->defbase, ob->actdef - 1);
-
+    const ListBase *defbase = BKE_object_defgroup_list(ob);
+    bDeformGroup *dg = BLI_findlink(defbase, BKE_object_defgroup_active_index_get(ob) - 1);
     if ((dg == NULL) || (BKE_object_defgroup_clear(ob, dg, !use_all_verts) == false)) {
       return OPERATOR_CANCELLED;
     }
@@ -3860,55 +3882,6 @@ void OBJECT_OT_vertex_group_mirror(wmOperatorType *ot)
 /** \} */
 
 /* -------------------------------------------------------------------- */
-/** \name Vertex Group Copy to Linked Operator
- * \{ */
-
-static int vertex_group_copy_to_linked_exec(bContext *C, wmOperator *UNUSED(op))
-{
-  Scene *scene = CTX_data_scene(C);
-  Object *ob_active = ED_object_context(C);
-  int retval = OPERATOR_CANCELLED;
-
-  FOREACH_SCENE_OBJECT_BEGIN (scene, ob_iter) {
-    if (ob_iter->type == ob_active->type) {
-      if (ob_iter != ob_active && ob_iter->data == ob_active->data) {
-        BLI_freelistN(&ob_iter->defbase);
-        BLI_duplicatelist(&ob_iter->defbase, &ob_active->defbase);
-        ob_iter->actdef = ob_active->actdef;
-
-        DEG_id_tag_update(&ob_iter->id, ID_RECALC_GEOMETRY);
-        WM_event_add_notifier(C, NC_OBJECT | ND_DRAW, ob_iter);
-        WM_event_add_notifier(C, NC_GEOM | ND_VERTEX_GROUP, ob_iter->data);
-
-        retval = OPERATOR_FINISHED;
-      }
-    }
-  }
-  FOREACH_SCENE_OBJECT_END;
-
-  return retval;
-}
-
-void OBJECT_OT_vertex_group_copy_to_linked(wmOperatorType *ot)
-{
-  /* identifiers */
-  ot->name = "Copy Vertex Groups to Linked";
-  ot->idname = "OBJECT_OT_vertex_group_copy_to_linked";
-  ot->description =
-      "Replace vertex groups of all users of the same geometry data by vertex groups of active "
-      "object";
-
-  /* api callbacks */
-  ot->poll = vertex_group_poll;
-  ot->exec = vertex_group_copy_to_linked_exec;
-
-  /* flags */
-  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-}
-
-/** \} */
-
-/* -------------------------------------------------------------------- */
 /** \name Vertex Group Copy to Selected Operator
  * \{ */
 
@@ -3972,7 +3945,7 @@ static int set_active_group_exec(bContext *C, wmOperator *op)
   int nr = RNA_enum_get(op->ptr, "group");
 
   BLI_assert(nr + 1 >= 0);
-  ob->actdef = nr + 1;
+  BKE_object_defgroup_active_index_set(ob, nr + 1);
 
   DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_GEOM | ND_VERTEX_GROUP, ob);
@@ -3999,7 +3972,8 @@ static const EnumPropertyItem *vgroup_itemf(bContext *C,
     return DummyRNA_NULL_items;
   }
 
-  for (a = 0, def = ob->defbase.first; def; def = def->next, a++) {
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  for (a = 0, def = defbase->first; def; def = def->next, a++) {
     tmp.value = a;
     tmp.icon = ICON_GROUP_VERTEX;
     tmp.identifier = def->name;
@@ -4048,13 +4022,13 @@ void OBJECT_OT_vertex_group_set_active(wmOperatorType *ot)
  * with the order of vgroups then call vgroup_do_remap after */
 static char *vgroup_init_remap(Object *ob)
 {
-  bDeformGroup *def;
-  int defbase_tot = BLI_listbase_count(&ob->defbase);
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  int defbase_tot = BLI_listbase_count(defbase);
   char *name_array = MEM_mallocN(MAX_VGROUP_NAME * sizeof(char) * defbase_tot, "sort vgroups");
   char *name;
 
   name = name_array;
-  for (def = ob->defbase.first; def; def = def->next) {
+  for (const bDeformGroup *def = defbase->first; def; def = def->next) {
     BLI_strncpy(name, def->name, MAX_VGROUP_NAME);
     name += MAX_VGROUP_NAME;
   }
@@ -4065,8 +4039,9 @@ static char *vgroup_init_remap(Object *ob)
 static int vgroup_do_remap(Object *ob, const char *name_array, wmOperator *op)
 {
   MDeformVert *dvert = NULL;
-  bDeformGroup *def;
-  int defbase_tot = BLI_listbase_count(&ob->defbase);
+  const bDeformGroup *def;
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  int defbase_tot = BLI_listbase_count(defbase);
 
   /* Needs a dummy index at the start. */
   int *sort_map_update = MEM_mallocN(sizeof(int) * (defbase_tot + 1), "sort vgroups");
@@ -4076,8 +4051,8 @@ static int vgroup_do_remap(Object *ob, const char *name_array, wmOperator *op)
   int i;
 
   name = name_array;
-  for (def = ob->defbase.first, i = 0; def; def = def->next, i++) {
-    sort_map[i] = BLI_findstringindex(&ob->defbase, name, offsetof(bDeformGroup, name));
+  for (def = defbase->first, i = 0; def; def = def->next, i++) {
+    sort_map[i] = BLI_findstringindex(defbase, name, offsetof(bDeformGroup, name));
     name += MAX_VGROUP_NAME;
 
     BLI_assert(sort_map[i] != -1);
@@ -4130,8 +4105,9 @@ static int vgroup_do_remap(Object *ob, const char *name_array, wmOperator *op)
   sort_map_update[0] = 0;
   BKE_object_defgroup_remap_update_users(ob, sort_map_update);
 
-  BLI_assert(sort_map_update[ob->actdef] >= 0);
-  ob->actdef = sort_map_update[ob->actdef];
+  BLI_assert(sort_map_update[BKE_object_defgroup_active_index_get(ob)] >= 0);
+  BKE_object_defgroup_active_index_set(ob,
+                                       sort_map_update[BKE_object_defgroup_active_index_get(ob)]);
 
   MEM_freeN(sort_map_update);
 
@@ -4159,6 +4135,7 @@ static void vgroup_sort_bone_hierarchy(Object *ob, ListBase *bonebase)
       bonebase = &armature->bonebase;
     }
   }
+  ListBase *defbase = BKE_object_defgroup_list_mutable(ob);
 
   if (bonebase != NULL) {
     Bone *bone;
@@ -4167,8 +4144,8 @@ static void vgroup_sort_bone_hierarchy(Object *ob, ListBase *bonebase)
       vgroup_sort_bone_hierarchy(ob, &bone->childbase);
 
       if (dg != NULL) {
-        BLI_remlink(&ob->defbase, dg);
-        BLI_addhead(&ob->defbase, dg);
+        BLI_remlink(defbase, dg);
+        BLI_addhead(defbase, dg);
       }
     }
   }
@@ -4189,10 +4166,12 @@ static int vertex_group_sort_exec(bContext *C, wmOperator *op)
   /* Init remapping. */
   name_array = vgroup_init_remap(ob);
 
+  ListBase *defbase = BKE_object_defgroup_list_mutable(ob);
+
   /* Sort vgroup names. */
   switch (sort_type) {
     case SORT_TYPE_NAME:
-      BLI_listbase_sort(&ob->defbase, vgroup_sort_name);
+      BLI_listbase_sort(defbase, vgroup_sort_name);
       break;
     case SORT_TYPE_BONEHIERARCHY:
       vgroup_sort_bone_hierarchy(ob, NULL);
@@ -4250,14 +4229,16 @@ static int vgroup_move_exec(bContext *C, wmOperator *op)
   int dir = RNA_enum_get(op->ptr, "direction");
   int ret = OPERATOR_FINISHED;
 
-  def = BLI_findlink(&ob->defbase, ob->actdef - 1);
+  ListBase *defbase = BKE_object_defgroup_list_mutable(ob);
+
+  def = BLI_findlink(defbase, BKE_object_defgroup_active_index_get(ob) - 1);
   if (!def) {
     return OPERATOR_CANCELLED;
   }
 
   name_array = vgroup_init_remap(ob);
 
-  if (BLI_listbase_link_move(&ob->defbase, def, dir)) {
+  if (BLI_listbase_link_move(defbase, def, dir)) {
     ret = vgroup_do_remap(ob, name_array, op);
 
     if (ret != OPERATOR_CANCELLED) {
@@ -4376,7 +4357,8 @@ static void vgroup_copy_active_to_sel_single(Object *ob, const int def_nr)
 
 static bool check_vertex_group_accessible(wmOperator *op, Object *ob, int def_nr)
 {
-  bDeformGroup *dg = BLI_findlink(&ob->defbase, def_nr);
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  bDeformGroup *dg = BLI_findlink(defbase, def_nr);
 
   if (!dg) {
     BKE_report(op->reports, RPT_ERROR, "Invalid vertex group index");
@@ -4498,7 +4480,7 @@ static int vertex_weight_set_active_exec(bContext *C, wmOperator *op)
   const int wg_index = RNA_int_get(op->ptr, "weight_group");
 
   if (wg_index != -1) {
-    ob->actdef = wg_index + 1;
+    BKE_object_defgroup_active_index_set(ob, wg_index + 1);
     DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
     WM_event_add_notifier(C, NC_OBJECT | ND_DRAW, ob);
   }
diff --git a/source/blender/editors/sculpt_paint/paint_utils.c b/source/blender/editors/sculpt_paint/paint_utils.c
index 2484f382ed4..709e04d807d 100644
--- a/source/blender/editors/sculpt_paint/paint_utils.c
+++ b/source/blender/editors/sculpt_paint/paint_utils.c
@@ -752,7 +752,7 @@ static int vert_select_ungrouped_exec(bContext *C, wmOperator *op)
   Object *ob = CTX_data_active_object(C);
   Mesh *me = ob->data;
 
-  if (BLI_listbase_is_empty(&ob->defbase) || (me->dvert == NULL)) {
+  if (BLI_listbase_is_empty(&me->vertex_group_names) || (me->dvert == NULL)) {
     BKE_report(op->reports, RPT_ERROR, "No weights/vertex groups on object");
     return OPERATOR_CANCELLED;
   }
diff --git a/source/blender/editors/sculpt_paint/paint_vertex.c b/source/blender/editors/sculpt_paint/paint_vertex.c
index 5c1cc6cadcf..9387b84f437 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex.c
@@ -1607,13 +1607,13 @@ static bool wpaint_stroke_test_start(bContext *C, wmOperator *op, const float mo
     /* check if we are attempting to paint onto a locked vertex group,
      * and other options disallow it from doing anything useful */
     bDeformGroup *dg;
-    dg = BLI_findlink(&ob->defbase, vgroup_index.active);
+    dg = BLI_findlink(&me->vertex_group_names, vgroup_index.active);
     if (dg->flag & DG_LOCK_WEIGHT) {
       BKE_report(op->reports, RPT_WARNING, "Active group is locked, aborting");
       return false;
     }
     if (vgroup_index.mirror != -1) {
-      dg = BLI_findlink(&ob->defbase, vgroup_index.mirror);
+      dg = BLI_findlink(&me->vertex_group_names, vgroup_index.mirror);
       if (dg->flag & DG_LOCK_WEIGHT) {
         BKE_report(op->reports, RPT_WARNING, "Mirror group is locked, aborting");
         return false;
@@ -1622,7 +1622,7 @@ static bool wpaint_stroke_test_start(bContext *C, wmOperator *op, const float mo
   }
 
   /* check that multipaint groups are unlocked */
-  defbase_tot = BLI_listbase_count(&ob->defbase);
+  defbase_tot = BLI_listbase_count(&me->vertex_group_names);
   defbase_sel = BKE_object_defgroup_selected_get(ob, defbase_tot, &defbase_tot_sel);
 
   if (ts->multipaint && defbase_tot_sel > 1) {
@@ -1636,7 +1636,7 @@ static bool wpaint_stroke_test_start(bContext *C, wmOperator *op, const float mo
 
     for (i = 0; i < defbase_tot; i++) {
       if (defbase_sel[i]) {
-        dg = BLI_findlink(&ob->defbase, i);
+        dg = BLI_findlink(&me->vertex_group_names, i);
         if (dg->flag & DG_LOCK_WEIGHT) {
           BKE_report(op->reports, RPT_WARNING, "Multipaint group is locked, aborting");
           MEM_freeN(defbase_sel);
@@ -2498,7 +2498,7 @@ static void wpaint_stroke_done(const bContext *C, struct PaintStroke *stroke)
 
     for (psys = ob->particlesystem.first; psys; psys = psys->next) {
       for (i = 0; i < PSYS_TOT_VG; i++) {
-        if (psys->vgroup[i] == ob->actdef) {
+        if (psys->vgroup[i] == BKE_object_defgroup_active_index_get(ob)) {
           psys->recalc |= ID_RECALC_PSYS_RESET;
           break;
         }
diff --git a/source/blender/editors/sculpt_paint/paint_vertex_color_ops.c b/source/blender/editors/sculpt_paint/paint_vertex_color_ops.c
index 96d22fe4a21..9f023dd6e63 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex_color_ops.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex_color_ops.c
@@ -149,7 +149,7 @@ static bool vertex_paint_from_weight(Object *ob)
   /* TODO: respect selection. */
   /* TODO: Do we want to take weights from evaluated mesh instead? 2.7x was not doing it anyway. */
   mp = me->mpoly;
-  vgroup_active = ob->actdef - 1;
+  vgroup_active = me->vertex_group_active_index - 1;
   for (int i = 0; i < me->totpoly; i++, mp++) {
     MLoopCol *lcol = &me->mloopcol[mp->loopstart];
     uint j = 0;
diff --git a/source/blender/editors/sculpt_paint/paint_vertex_weight_ops.c b/source/blender/editors/sculpt_paint/paint_vertex_weight_ops.c
index 5e047283534..cb8dc838422 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex_weight_ops.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex_weight_ops.c
@@ -183,7 +183,7 @@ static int weight_sample_invoke(bContext *C, wmOperator *op, const wmEvent *even
   ED_view3d_viewcontext_init(C, &vc, depsgraph);
   me = BKE_mesh_from_object(vc.obact);
 
-  if (me && me->dvert && vc.v3d && vc.rv3d && (vc.obact->actdef != 0)) {
+  if (me && me->dvert && vc.v3d && vc.rv3d && (me->vertex_group_active_index != 0)) {
     const bool use_vert_sel = (me->editflag & ME_EDIT_PAINT_VERT_SEL) != 0;
     int v_idx_best = -1;
     uint index;
@@ -213,9 +213,9 @@ static int weight_sample_invoke(bContext *C, wmOperator *op, const wmEvent *even
     if (v_idx_best != -1) { /* should always be valid */
       ToolSettings *ts = vc.scene->toolsettings;
       Brush *brush = BKE_paint_brush(&ts->wpaint->paint);
-      const int vgroup_active = vc.obact->actdef - 1;
+      const int vgroup_active = me->vertex_group_active_index - 1;
       float vgroup_weight = BKE_defvert_find_weight(&me->dvert[v_idx_best], vgroup_active);
-      const int defbase_tot = BLI_listbase_count(&vc.obact->defbase);
+      const int defbase_tot = BLI_listbase_count(&me->vertex_group_names);
       bool use_lock_relative = ts->wpaint_lock_relative;
       bool *defbase_locked = NULL, *defbase_unlocked = NULL;
 
@@ -331,8 +331,8 @@ static const EnumPropertyItem *weight_paint_sample_enum_itemf(bContext *C,
       ED_view3d_viewcontext_init(C, &vc, depsgraph);
       me = BKE_mesh_from_object(vc.obact);
 
-      if (me && me->dvert && vc.v3d && vc.rv3d && vc.obact->defbase.first) {
-        const int defbase_tot = BLI_listbase_count(&vc.obact->defbase);
+      if (me && me->dvert && vc.v3d && vc.rv3d && me->vertex_group_names.first) {
+        const int defbase_tot = BLI_listbase_count(&me->vertex_group_names);
         const bool use_vert_sel = (me->editflag & ME_EDIT_PAINT_VERT_SEL) != 0;
         int *groups = MEM_callocN(defbase_tot * sizeof(int), "groups");
         bool found = false;
@@ -372,7 +372,7 @@ static const EnumPropertyItem *weight_paint_sample_enum_itemf(bContext *C,
           int totitem = 0;
           int i = 0;
           bDeformGroup *dg;
-          for (dg = vc.obact->defbase.first; dg && i < defbase_tot; i++, dg = dg->next) {
+          for (dg = me->vertex_group_names.first; dg && i < defbase_tot; i++, dg = dg->next) {
             if (groups[i]) {
               item_tmp.identifier = item_tmp.name = dg->name;
               item_tmp.value = i;
@@ -401,7 +401,7 @@ static int weight_sample_group_exec(bContext *C, wmOperator *op)
   ED_view3d_viewcontext_init(C, &vc, depsgraph);
 
   BLI_assert(type + 1 >= 0);
-  vc.obact->actdef = type + 1;
+  BKE_object_defgroup_active_index_set(vc.obact, type + 1);
 
   DEG_id_tag_update(&vc.obact->id, ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_OBJECT | ND_DRAW, vc.obact);
@@ -458,7 +458,7 @@ static bool weight_paint_set(Object *ob, float paintweight)
     return false;
   }
 
-  vgroup_active = ob->actdef - 1;
+  vgroup_active = BKE_object_defgroup_active_index_get(ob) - 1;
 
   /* if mirror painting, find the other group */
   if (ME_USING_MIRROR_X_VERTEX_GROUPS(me)) {
@@ -815,7 +815,7 @@ static int paint_weight_gradient_exec(bContext *C, wmOperator *op)
   data.sco_start = sco_start;
   data.sco_end = sco_end;
   data.sco_line_div = 1.0f / len_v2v2(sco_start, sco_end);
-  data.def_nr = ob->actdef - 1;
+  data.def_nr = BKE_object_defgroup_active_index_get(ob) - 1;
   data.use_select = (me->editflag & (ME_EDIT_PAINT_FACE_SEL | ME_EDIT_PAINT_VERT_SEL)) != 0;
   data.vert_cache = vert_cache;
   data.vert_visit = NULL;
@@ -863,7 +863,7 @@ static int paint_weight_gradient_exec(bContext *C, wmOperator *op)
   }
 
   if (scene->toolsettings->auto_normalize) {
-    const int vgroup_num = BLI_listbase_count(&ob->defbase);
+    const int vgroup_num = BLI_listbase_count(&me->vertex_group_names);
     bool *vgroup_validmap = BKE_object_defgroup_validmap_get(ob, vgroup_num);
     if (vgroup_validmap != NULL) {
       MDeformVert *dvert = me->dvert;
diff --git a/source/blender/editors/sculpt_paint/paint_vertex_weight_utils.c b/source/blender/editors/sculpt_paint/paint_vertex_weight_utils.c
index d6a118bbd59..19ffa0c952d 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex_weight_utils.c
+++ b/source/blender/editors/sculpt_paint/paint_vertex_weight_utils.c
@@ -79,8 +79,10 @@ bool ED_wpaint_ensure_data(bContext *C,
     WM_event_add_notifier(C, NC_GEOM | ND_DATA, me);
   }
 
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+
   /* this happens on a Bone select, when no vgroup existed yet */
-  if (ob->actdef <= 0) {
+  if (me->vertex_group_active_index <= 0) {
     Object *modob;
     if ((modob = BKE_modifiers_is_deformed_by_armature(ob))) {
       Bone *actbone = ((bArmature *)modob->data)->act_bone;
@@ -94,32 +96,33 @@ bool ED_wpaint_ensure_data(bContext *C,
             DEG_relations_tag_update(CTX_data_main(C));
           }
           else {
-            int actdef = 1 + BLI_findindex(&ob->defbase, dg);
+
+            int actdef = 1 + BLI_findindex(defbase, dg);
             BLI_assert(actdef >= 0);
-            ob->actdef = actdef;
+            me->vertex_group_active_index = actdef;
           }
         }
       }
     }
   }
-  if (BLI_listbase_is_empty(&ob->defbase)) {
+  if (BLI_listbase_is_empty(defbase)) {
     BKE_object_defgroup_add(ob);
     DEG_relations_tag_update(CTX_data_main(C));
   }
 
   /* ensure we don't try paint onto an invalid group */
-  if (ob->actdef <= 0) {
+  if (me->vertex_group_active_index <= 0) {
     BKE_report(reports, RPT_WARNING, "No active vertex group for painting, aborting");
     return false;
   }
 
   if (vgroup_index) {
-    vgroup_index->active = ob->actdef - 1;
+    vgroup_index->active = me->vertex_group_active_index - 1;
   }
 
   if (flag & WPAINT_ENSURE_MIRROR) {
     if (ME_USING_MIRROR_X_VERTEX_GROUPS(me)) {
-      int mirror = ED_wpaint_mirror_vgroup_ensure(ob, ob->actdef - 1);
+      int mirror = ED_wpaint_mirror_vgroup_ensure(ob, me->vertex_group_active_index - 1);
       if (vgroup_index) {
         vgroup_index->mirror = mirror;
       }
@@ -133,7 +136,8 @@ bool ED_wpaint_ensure_data(bContext *C,
 /* mirror_vgroup is set to -1 when invalid */
 int ED_wpaint_mirror_vgroup_ensure(Object *ob, const int vgroup_active)
 {
-  bDeformGroup *defgroup = BLI_findlink(&ob->defbase, vgroup_active);
+  const ListBase *defbase = BKE_object_defgroup_list(ob);
+  bDeformGroup *defgroup = BLI_findlink(defbase, vgroup_active);
 
   if (defgroup) {
     int mirrdef;
@@ -143,7 +147,7 @@ int ED_wpaint_mirror_vgroup_ensure(Object *ob, const int vgroup_active)
     mirrdef = BKE_object_defgroup_name_index(ob, name_flip);
     if (mirrdef == -1) {
       if (BKE_object_defgroup_new(ob, name_flip)) {
-        mirrdef = BLI_listbase_count(&ob->defbase) - 1;
+        mirrdef = BLI_listbase_count(defbase) - 1;
       }
     }
 
diff --git a/source/blender/editors/space_outliner/outliner_select.c b/source/blender/editors/space_outliner/outliner_select.c
index f248711633e..35015356f0b 100644
--- a/source/blender/editors/space_outliner/outliner_select.c
+++ b/source/blender/editors/space_outliner/outliner_select.c
@@ -42,6 +42,7 @@
 #include "BKE_collection.h"
 #include "BKE_constraint.h"
 #include "BKE_context.h"
+#include "BKE_deform.h"
 #include "BKE_gpencil.h"
 #include "BKE_gpencil_modifier.h"
 #include "BKE_layer.h"
@@ -450,7 +451,7 @@ static void tree_element_defgroup_activate(bContext *C, TreeElement *te, TreeSto
   /* id in tselem is object */
   Object *ob = (Object *)tselem->id;
   BLI_assert(te->index + 1 >= 0);
-  ob->actdef = te->index + 1;
+  BKE_object_defgroup_active_index_set(ob, te->index + 1);
 
   DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_OBJECT | ND_TRANSFORM, ob);
@@ -830,7 +831,7 @@ static eOLDrawState tree_element_defgroup_state_get(const ViewLayer *view_layer,
 {
   const Object *ob = (const Object *)tselem->id;
   if (ob == OBACT(view_layer)) {
-    if (ob->actdef == te->index + 1) {
+    if (BKE_object_defgroup_active_index_get(ob) == te->index + 1) {
       return OL_DRAWSEL_NORMAL;
     }
   }
diff --git a/source/blender/editors/space_outliner/outliner_tree.c b/source/blender/editors/space_outliner/outliner_tree.c
index 334c901b6d3..c08707b7a6a 100644
--- a/source/blender/editors/space_outliner/outliner_tree.c
+++ b/source/blender/editors/space_outliner/outliner_tree.c
@@ -1,4 +1,4 @@
-/*
+/*
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 2
@@ -62,6 +62,7 @@
 #include "BLT_translation.h"
 
 #include "BKE_armature.h"
+#include "BKE_deform.h"
 #include "BKE_layer.h"
 #include "BKE_lib_id.h"
 #include "BKE_main.h"
@@ -552,17 +553,20 @@ static void outliner_add_object_contents(SpaceOutliner *space_outliner,
   }
 
   /* vertex groups */
-  if (!BLI_listbase_is_empty(&ob->defbase)) {
-    TreeElement *tenla = outliner_add_element(
-        space_outliner, &te->subtree, ob, te, TSE_DEFGROUP_BASE, 0);
-    tenla->name = IFACE_("Vertex Groups");
+  if (ELEM(ob->type, OB_MESH, OB_GPENCIL, OB_LATTICE)) {
+    const ListBase *defbase = BKE_object_defgroup_list(ob);
+    if (!BLI_listbase_is_empty(defbase)) {
+      TreeElement *tenla = outliner_add_element(
+          space_outliner, &te->subtree, ob, te, TSE_DEFGROUP_BASE, 0);
+      tenla->name = IFACE_("Vertex Groups");
 
-    int index;
-    LISTBASE_FOREACH_INDEX (bDeformGroup *, defgroup, &ob->defbase, index) {
-      TreeElement *ten = outliner_add_element(
-          space_outliner, &tenla->subtree, ob, tenla, TSE_DEFGROUP, index);
-      ten->name = defgroup->name;
-      ten->directdata = defgroup;
+      int index;
+      LISTBASE_FOREACH_INDEX (bDeformGroup *, defgroup, defbase, index) {
+        TreeElement *ten = outliner_add_element(
+            space_outliner, &tenla->subtree, ob, tenla, TSE_DEFGROUP, index);
+        ten->name = defgroup->name;
+        ten->directdata = defgroup;
+      }
     }
   }
 
diff --git a/source/blender/editors/space_spreadsheet/spreadsheet_data_source_geometry.cc b/source/blender/editors/space_spreadsheet/spreadsheet_data_source_geometry.cc
index 44b17b8c391..e38c70afd0f 100644
--- a/source/blender/editors/space_spreadsheet/spreadsheet_data_source_geometry.cc
+++ b/source/blender/editors/space_spreadsheet/spreadsheet_data_source_geometry.cc
@@ -414,7 +414,6 @@ GeometrySet spreadsheet_get_display_geometry_set(const SpaceSpreadsheet *sspread
         Mesh *mesh = (Mesh *)object_orig->data;
         mesh_component.replace(mesh, GeometryOwnershipType::ReadOnly);
       }
-      mesh_component.copy_vertex_group_names_from_object(*object_orig);
     }
     else if (object_orig->type == OB_POINTCLOUD) {
       PointCloud *pointcloud = (PointCloud *)object_orig->data;
@@ -432,7 +431,6 @@ GeometrySet spreadsheet_get_display_geometry_set(const SpaceSpreadsheet *sspread
       BKE_mesh_wrapper_ensure_mdata(mesh);
       MeshComponent &mesh_component = geometry_set.get_component_for_write<MeshComponent>();
       mesh_component.replace(mesh, GeometryOwnershipType::ReadOnly);
-      mesh_component.copy_vertex_group_names_from_object(*object_eval);
     }
     else {
       if (BLI_listbase_count(&sspreadsheet->context_path) == 1) {
diff --git a/source/blender/editors/space_view3d/view3d_buttons.c b/source/blender/editors/space_view3d/view3d_buttons.c
index 554b6c0f34f..3428a738dde 100644
--- a/source/blender/editors/space_view3d/view3d_buttons.c
+++ b/source/blender/editors/space_view3d/view3d_buttons.c
@@ -1310,7 +1310,9 @@ static void view3d_panel_vgroup(const bContext *C, Panel *panel)
 
     vgroup_validmap = BKE_object_defgroup_subset_from_select_type(
         ob, subset_type, &vgroup_tot, &subset_count);
-    for (i = 0, dg = ob->defbase.first; dg; i++, dg = dg->next) {
+    const ListBase *defbase = BKE_object_defgroup_list(ob);
+
+    for (i = 0, dg = defbase->first; dg; i++, dg = dg->next) {
       bool locked = (dg->flag & DG_LOCK_WEIGHT) != 0;
       if (vgroup_validmap[i]) {
         MDeformWeight *dw = BKE_defvert_find_index(dv, i);
@@ -1336,7 +1338,7 @@ static void view3d_panel_vgroup(const bContext *C, Panel *panel)
           but_ptr = UI_but_operator_ptr_get(but);
           RNA_int_set(but_ptr, "weight_group", i);
           UI_but_drawflag_enable(but, UI_BUT_TEXT_RIGHT);
-          if (ob->actdef != i + 1) {
+          if (BKE_object_defgroup_active_index_get(ob) != i + 1) {
             UI_but_flag_enable(but, UI_BUT_INACTIVE);
           }
           xco += x;