From 4be87e97f48533e16594b6ec73980ffb2ba12ade Mon Sep 17 00:00:00 2001
From: Jacques Lucke <jacques@blender.org>
Date: Thu, 3 Feb 2022 16:52:16 +0100
Subject: [PATCH] Fix T94435: remove anonymous attributes when applying
 modifier

Differential Revision: https://developer.blender.org/D13994
---
 source/blender/blenkernel/BKE_customdata.h     |  5 +++++
 source/blender/blenkernel/intern/customdata.cc | 18 ++++++++++++++++++
 .../blender/editors/object/object_modifier.c   |  6 ++++++
 3 files changed, 29 insertions(+)

diff --git a/source/blender/blenkernel/BKE_customdata.h b/source/blender/blenkernel/BKE_customdata.h
index 76389b0c66f..38b43e36feb 100644
--- a/source/blender/blenkernel/BKE_customdata.h
+++ b/source/blender/blenkernel/BKE_customdata.h
@@ -253,6 +253,11 @@ bool CustomData_free_layer_active(struct CustomData *data, int type, int totelem
  */
 void CustomData_free_layers(struct CustomData *data, int type, int totelem);
 
+/**
+ * Free all anonymous attributes.
+ */
+void CustomData_free_layers_anonymous(struct CustomData *data, int totelem);
+
 /**
  * Returns true if a layer with the specified type exists.
  */
diff --git a/source/blender/blenkernel/intern/customdata.cc b/source/blender/blenkernel/intern/customdata.cc
index 02b50027ef9..e4c18325d76 100644
--- a/source/blender/blenkernel/intern/customdata.cc
+++ b/source/blender/blenkernel/intern/customdata.cc
@@ -2780,6 +2780,24 @@ void CustomData_free_layers(CustomData *data, int type, int totelem)
   }
 }
 
+void CustomData_free_layers_anonymous(struct CustomData *data, int totelem)
+{
+  while (true) {
+    bool found_anonymous_layer = false;
+    for (int i = 0; i < data->totlayer; i++) {
+      const CustomDataLayer *layer = &data->layers[i];
+      if (layer->anonymous_id != NULL) {
+        CustomData_free_layer(data, layer->type, totelem, i);
+        found_anonymous_layer = true;
+        break;
+      }
+    }
+    if (!found_anonymous_layer) {
+      break;
+    }
+  }
+}
+
 bool CustomData_has_layer(const CustomData *data, int type)
 {
   return (CustomData_get_layer_index(data, type) != -1);
diff --git a/source/blender/editors/object/object_modifier.c b/source/blender/editors/object/object_modifier.c
index 71ad54383a6..4ac2a9dca62 100644
--- a/source/blender/editors/object/object_modifier.c
+++ b/source/blender/editors/object/object_modifier.c
@@ -763,6 +763,12 @@ static bool modifier_apply_obdata(
       BKE_object_material_from_eval_data(bmain, ob, &mesh_applied->id);
       BKE_mesh_nomain_to_mesh(mesh_applied, me, ob, &CD_MASK_MESH, true);
 
+      /* Anonymous attributes shouldn't by available on the applied geometry. */
+      CustomData_free_layers_anonymous(&me->vdata, me->totvert);
+      CustomData_free_layers_anonymous(&me->edata, me->totedge);
+      CustomData_free_layers_anonymous(&me->pdata, me->totpoly);
+      CustomData_free_layers_anonymous(&me->ldata, me->totloop);
+
       if (md_eval->type == eModifierType_Multires) {
         multires_customdata_delete(me);
       }