From bdfb3ea6e75084ed935367c798564d08510080b2 Mon Sep 17 00:00:00 2001
From: Philipp Oeser <philipp@blender.org>
Date: Mon, 4 Nov 2024 17:00:51 +0100
Subject: [PATCH] Fix #129727: GPv3: renaming bones does not rename vertex
 groups

First issue is that `BKE_modifiers_uses_armature` wasnt working for GP
objects and the second one is that vgroup names are stored in
CurvesGeometry for GP (so that needs special handling, now done, same as
in `BKE_object_defgroup_set_name`).

Pull Request: https://projects.blender.org/blender/blender/pulls/129794
---
 source/blender/blenkernel/intern/modifier.cc       | 9 ++++++++-
 source/blender/editors/armature/armature_naming.cc | 6 ++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/source/blender/blenkernel/intern/modifier.cc b/source/blender/blenkernel/intern/modifier.cc
index 32cf20ac483..883ea48410e 100644
--- a/source/blender/blenkernel/intern/modifier.cc
+++ b/source/blender/blenkernel/intern/modifier.cc
@@ -770,7 +770,14 @@ bool BKE_modifiers_uses_armature(Object *ob, bArmature *arm)
 
   for (; md; md = md->next) {
     if (md->type == eModifierType_Armature) {
-      ArmatureModifierData *amd = (ArmatureModifierData *)md;
+      ArmatureModifierData *amd = reinterpret_cast<ArmatureModifierData *>(md);
+      if (amd->object && amd->object->data == arm) {
+        return true;
+      }
+    }
+    else if (md->type == eModifierType_GreasePencilArmature) {
+      GreasePencilArmatureModifierData *amd = reinterpret_cast<GreasePencilArmatureModifierData *>(
+          md);
       if (amd->object && amd->object->data == arm) {
         return true;
       }
diff --git a/source/blender/editors/armature/armature_naming.cc b/source/blender/editors/armature/armature_naming.cc
index eb0edad95ae..af2a8273109 100644
--- a/source/blender/editors/armature/armature_naming.cc
+++ b/source/blender/editors/armature/armature_naming.cc
@@ -262,6 +262,12 @@ void ED_armature_bone_rename(Main *bmain,
         bDeformGroup *dg = BKE_object_defgroup_find_name(ob, oldname);
         if (dg) {
           STRNCPY(dg->name, newname);
+
+          if (ob->type == OB_GREASE_PENCIL) {
+            /* Update vgroup names stored in CurvesGeometry */
+            BKE_grease_pencil_vgroup_name_update(ob, oldname, dg->name);
+          }
+
           DEG_id_tag_update(static_cast<ID *>(ob->data), ID_RECALC_GEOMETRY);
         }
       }