Geometry Nodes: add utility to ensure that no geometry components are shared

source/blender/blenkernel/BKE_geometry_set.hh

@@ -245,6 +245,13 @@ struct GeometrySet {
    * instances so that they can be owned.
    */
   void ensure_owns_all_data();
+  /**
+   * Typically, multiple #GeometrySet may share the same #GeometryComponent. This is fine as long
+   * as we can guarantee that the data is read-only. However, if some geometry is available in
+   * Python, that guarantee is not possible currently. For that case it can make sense that the
+   * #GeometrySet is the unique owner of the geometries it contains.
+   */
+  void ensure_no_shared_components();
 
   using AttributeForeachCallback = FunctionRef<void(StringRef attribute_id,
                                                     const AttributeMetaData &meta_data,

source/blender/blenkernel/intern/geometry_set.cc

@@ -296,6 +296,15 @@ bool GeometrySet::owns_direct_data() const
   return true;
 }
 
+void GeometrySet::ensure_no_shared_components()
+{
+  for (const int i : IndexRange(this->components_.size())) {
+    if (components_[i]) {
+      this->get_component_for_write(GeometryComponent::Type(i));
+    }
+  }
+}
+
 const Mesh *GeometrySet::get_mesh() const
 {
   const MeshComponent *component = this->get_component<MeshComponent>();