support anonymous attributes in foreach_attribute

source/blender/blenkernel/BKE_anonymous_attribute.h

@@ -0,0 +1,37 @@
+/*
+ * 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
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct AnonymousAttributeID AnonymousAttributeID;
+
+AnonymousAttributeID *BKE_anonymous_attribute_id_new_weak(const char *debug_name);
+AnonymousAttributeID *BKE_anonymous_attribute_id_new_strong(const char *debug_name);
+bool BKE_anonymous_attribute_id_has_strong_references(const AnonymousAttributeID *anonymous_id);
+void BKE_anonymous_attribute_id_increment_weak(const AnonymousAttributeID *anonymous_id);
+void BKE_anonymous_attribute_id_increment_strong(const AnonymousAttributeID *anonymous_id);
+void BKE_anonymous_attribute_id_decrement_weak(const AnonymousAttributeID *anonymous_id);
+void BKE_anonymous_attribute_id_decrement_strong(const AnonymousAttributeID *anonymous_id);
+const char *BKE_anonymous_attribute_id_debug_name(const AnonymousAttributeID *anonymous_id);
+const char *BKE_anonymous_attribute_id_internal_name(const AnonymousAttributeID *anonymous_id);
+
+#ifdef __cplusplus
+}
+#endif

source/blender/blenkernel/BKE_anonymous_attribute.hh

@@ -0,0 +1,223 @@
+/*
+ * 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
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#include <atomic>
+#include <string>
+
+#include "BLI_hash.hh"
+#include "BLI_string_ref.hh"
+
+#include "BKE_anonymous_attribute.h"
+
+namespace blender::bke {
+
+template<bool IsStrongReference> class OwnedAnonymousAttributeID {
+ private:
+  const AnonymousAttributeID *data_ = nullptr;
+
+ public:
+  OwnedAnonymousAttributeID() = default;
+
+  explicit OwnedAnonymousAttributeID(StringRefNull debug_name)
+  {
+    if constexpr (IsStrongReference) {
+      data_ = BKE_anonymous_attribute_id_new_strong(debug_name.c_str());
+    }
+    else {
+      data_ = BKE_anonymous_attribute_id_new_weak(debug_name.c_str());
+    }
+  }
+
+  /* This transfers ownership, so no incref is necessary. */
+  explicit OwnedAnonymousAttributeID(const AnonymousAttributeID *anonymous_id)
+      : data_(anonymous_id)
+  {
+  }
+
+  template<bool OtherIsStrong>
+  OwnedAnonymousAttributeID(const OwnedAnonymousAttributeID<OtherIsStrong> &other)
+  {
+    data_ = other.data_;
+    this->incref();
+  }
+
+  template<bool OtherIsStrong>
+  OwnedAnonymousAttributeID(OwnedAnonymousAttributeID<OtherIsStrong> &&other)
+  {
+    data_ = other.data_;
+    this->incref();
+    other.decref();
+    other.data_ = nullptr;
+  }
+
+  ~OwnedAnonymousAttributeID()
+  {
+    this->decref();
+  }
+
+  template<bool OtherIsStrong>
+  OwnedAnonymousAttributeID &operator=(const OwnedAnonymousAttributeID<OtherIsStrong> &other)
+  {
+    if (this == &other) {
+      return *this;
+    }
+    this->~OwnedAnonymousAttributeID();
+    new (this) OwnedAnonymousAttributeID(other);
+    return *this;
+  }
+
+  template<bool OtherIsStrong>
+  OwnedAnonymousAttributeID &operator=(OwnedAnonymousAttributeID<OtherIsStrong> &&other)
+  {
+    if (this == &other) {
+      return *this;
+    }
+    this->~OwnedAnonymousAttributeID();
+    new (this) OwnedAnonymousAttributeID(std::move(other));
+    return *this;
+  }
+
+  operator bool() const
+  {
+    return data_ != nullptr;
+  }
+
+  StringRefNull debug_name() const
+  {
+    BLI_assert(data_ != nullptr);
+    return BKE_anonymous_attribute_id_debug_name(data_);
+  }
+
+  bool has_strong_references() const
+  {
+    BLI_assert(data_ != nullptr);
+    return BKE_anonymous_attribute_id_has_strong_references(data_);
+  }
+
+  const AnonymousAttributeID *extract()
+  {
+    const AnonymousAttributeID *extracted_data = data_;
+    /* Don't decref because the caller becomes the new owner. */
+    data_ = nullptr;
+    return extracted_data;
+  }
+
+  const AnonymousAttributeID *get()
+  {
+    return data_;
+  }
+
+ private:
+  void incref()
+  {
+    if (data_ == nullptr) {
+      return;
+    }
+    if constexpr (IsStrongReference) {
+      BKE_anonymous_attribute_id_increment_strong(data_);
+    }
+    else {
+      BKE_anonymous_attribute_id_increment_weak(data_);
+    }
+  }
+
+  void decref()
+  {
+    if (data_ == nullptr) {
+      return;
+    }
+    if constexpr (IsStrongReference) {
+      BKE_anonymous_attribute_id_decrement_strong(data_);
+    }
+    else {
+      BKE_anonymous_attribute_id_decrement_weak(data_);
+    }
+  }
+};
+
+using StrongAnonymousAttributeID = OwnedAnonymousAttributeID<true>;
+using WeakAnonymousAttributeID = OwnedAnonymousAttributeID<false>;
+
+class AttributeIDRef {
+ private:
+  StringRef name_;
+  const AnonymousAttributeID *anonymous_id_ = nullptr;
+
+ public:
+  AttributeIDRef() = default;
+
+  AttributeIDRef(StringRef name) : name_(name)
+  {
+  }
+
+  AttributeIDRef(StringRefNull name) : name_(name)
+  {
+  }
+
+  AttributeIDRef(const char *name) : name_(name)
+  {
+  }
+
+  AttributeIDRef(const std::string &name) : name_(name)
+  {
+  }
+
+  /* The anonymous id is only borrowed, the caller has to keep a reference to it. */
+  AttributeIDRef(const AnonymousAttributeID *anonymous_id) : anonymous_id_(anonymous_id)
+  {
+  }
+
+  operator bool() const
+  {
+    return this->is_named() || this->is_anonymous();
+  }
+
+  friend bool operator==(const AttributeIDRef &a, const AttributeIDRef &b)
+  {
+    return a.anonymous_id_ == b.anonymous_id_ && a.name_ == b.name_;
+  }
+
+  uint64_t hash() const
+  {
+    return get_default_hash_2(name_, anonymous_id_);
+  }
+
+  bool is_named() const
+  {
+    return !name_.is_empty();
+  }
+
+  bool is_anonymous() const
+  {
+    return anonymous_id_ != nullptr;
+  }
+
+  StringRef name() const
+  {
+    BLI_assert(this->is_named());
+    return name_;
+  }
+
+  const AnonymousAttributeID &anonymous_id() const
+  {
+    BLI_assert(this->is_anonymous());
+    return *anonymous_id_;
+  }
+};
+
+}  // namespace blender::bke

source/blender/blenkernel/BKE_attribute_access.hh

@@ -22,6 +22,7 @@
 #include "FN_generic_span.hh"
 #include "FN_generic_virtual_array.hh"
 
+#include "BKE_anonymous_attribute.hh"
 #include "BKE_attribute.h"
 
 #include "BLI_color.hh"
@@ -104,8 +105,8 @@ struct AttributeInitMove : public AttributeInit {
 };
 
 /* Returns false when the iteration should be stopped. */
-using AttributeForeachCallback = blender::FunctionRef<bool(blender::StringRefNull attribute_name,
-                                                           const AttributeMetaData &meta_data)>;
+using AttributeForeachCallback = blender::FunctionRef<bool(
+    const blender::bke::AttributeIDRef &attribute_id, const AttributeMetaData &meta_data)>;
 
 namespace blender::bke {
 
@@ -333,26 +334,30 @@ class CustomDataAttributes {
 
   void reallocate(const int size);
 
-  std::optional<blender::fn::GSpan> get_for_read(const blender::StringRef name) const;
+  std::optional<blender::fn::GSpan> get_for_read(
+      const blender::bke::AttributeIDRef &attribute_id) const;
 
-  blender::fn::GVArrayPtr get_for_read(const StringRef name,
+  blender::fn::GVArrayPtr get_for_read(const AttributeIDRef &attribute_id,
                                        const CustomDataType data_type,
                                        const void *default_value) const;
 
   template<typename T>
-  blender::fn::GVArray_Typed<T> get_for_read(const blender::StringRef name,
+  blender::fn::GVArray_Typed<T> get_for_read(const blender::bke::AttributeIDRef &attribute_id,
                                              const T &default_value) const
   {
     const blender::fn::CPPType &cpp_type = blender::fn::CPPType::get<T>();
     const CustomDataType type = blender::bke::cpp_type_to_custom_data_type(cpp_type);
-    GVArrayPtr varray = this->get_for_read(name, type, &default_value);
+    GVArrayPtr varray = this->get_for_read(attribute_id, type, &default_value);
     return blender::fn::GVArray_Typed<T>(std::move(varray));
   }
 
-  std::optional<blender::fn::GMutableSpan> get_for_write(const blender::StringRef name);
-  bool create(const blender::StringRef name, const CustomDataType data_type);
-  bool create_by_move(const blender::StringRef name, const CustomDataType data_type, void *buffer);
-  bool remove(const blender::StringRef name);
+  std::optional<blender::fn::GMutableSpan> get_for_write(
+      const blender::bke::AttributeIDRef &attribute_id);
+  bool create(const blender::bke::AttributeIDRef &attribute_id, const CustomDataType data_type);
+  bool create_by_move(const blender::bke::AttributeIDRef &attribute_id,
+                      const CustomDataType data_type,
+                      void *buffer);
+  bool remove(const blender::bke::AttributeIDRef &attribute_id);
 
   bool foreach_attribute(const AttributeForeachCallback callback,
                          const AttributeDomain domain) const;

source/blender/blenkernel/BKE_customdata.h

@@ -33,6 +33,7 @@
 extern "C" {
 #endif
 
+struct AnonymousAttributeID;
 struct BMesh;
 struct BlendDataReader;
 struct BlendWriter;
@@ -193,6 +194,12 @@ void *CustomData_add_layer_named(struct CustomData *data,
                                  void *layer,
                                  int totelem,
                                  const char *name);
+void *CustomData_add_layer_anonymous(struct CustomData *data,
+                                     int type,
+                                     eCDAllocType alloctype,
+                                     void *layer,
+                                     int totelem,
+                                     const struct AnonymousAttributeID *anonymous_id);
 
 /* frees the active or first data layer with the give type.
  * returns 1 on success, 0 if no layer with the given type is found
@@ -231,6 +238,11 @@ void *CustomData_duplicate_referenced_layer_named(struct CustomData *data,
                                                   const int type,
                                                   const char *name,
                                                   const int totelem);
+void *CustomData_duplicate_referenced_layer_anonymous(
+    CustomData *data,
+    const int type,
+    const struct AnonymousAttributeID *anonymous_id,
+    const int totelem);
 bool CustomData_is_referenced_layer(struct CustomData *data, int type);
 
 /* Duplicate all the layers with flag NOFREE, and remove the flag from duplicated layers. */

source/blender/blenkernel/BKE_geometry_set.hh

@@ -31,6 +31,7 @@
 #include "BLI_user_counter.hh"
 #include "BLI_vector_set.hh"
 
+#include "BKE_anonymous_attribute.hh"
 #include "BKE_attribute_access.hh"
 #include "BKE_geometry_set.h"
 
@@ -88,11 +89,11 @@ class GeometryComponent {
   GeometryComponentType type() const;
 
   /* Return true when any attribute with this name exists, including built in attributes. */
-  bool attribute_exists(const blender::StringRef attribute_name) const;
+  bool attribute_exists(const blender::bke::AttributeIDRef &attribute_id) const;
 
   /* Return the data type and domain of an attribute with the given name if it exists. */
   std::optional<AttributeMetaData> attribute_get_meta_data(
-      const blender::StringRef attribute_name) const;
+      const blender::bke::AttributeIDRef &attribute_id) const;
 
   /* Returns true when the geometry component supports this attribute domain. */
   bool attribute_domain_supported(const AttributeDomain domain) const;
@@ -104,12 +105,12 @@ class GeometryComponent {
   /* Get read-only access to the highest priority attribute with the given name.
    * Returns null if the attribute does not exist. */
   blender::bke::ReadAttributeLookup attribute_try_get_for_read(
-      const blender::StringRef attribute_name) const;
+      const blender::bke::AttributeIDRef &attribute_id) const;
 
   /* Get read and write access to the highest priority attribute with the given name.
    * Returns null if the attribute does not exist. */
   blender::bke::WriteAttributeLookup attribute_try_get_for_write(
-      const blender::StringRef attribute_name);
+      const blender::bke::AttributeIDRef &attribute_id);
 
   /* Get a read-only attribute for the domain based on the given attribute. This can be used to
    * interpolate from one domain to another.
@@ -120,10 +121,10 @@ class GeometryComponent {
       const AttributeDomain to_domain) const;
 
   /* Returns true when the attribute has been deleted. */
-  bool attribute_try_delete(const blender::StringRef attribute_name);
+  bool attribute_try_delete(const blender::bke::AttributeIDRef &attribute_id);
 
   /* Returns true when the attribute has been created. */
-  bool attribute_try_create(const blender::StringRef attribute_name,
+  bool attribute_try_create(const blender::bke::AttributeIDRef &attribute_id,
                             const AttributeDomain domain,
                             const CustomDataType data_type,
                             const AttributeInit &initializer);
@@ -133,7 +134,7 @@ class GeometryComponent {
   bool attribute_try_create_builtin(const blender::StringRef attribute_name,
                                     const AttributeInit &initializer);
 
-  blender::Set<std::string> attribute_names() const;
+  blender::Set<blender::bke::AttributeIDRef> attribute_ids() const;
   bool attribute_foreach(const AttributeForeachCallback callback) const;
 
   virtual bool is_empty() const;
@@ -142,7 +143,7 @@ class GeometryComponent {
    * Returns null when the attribute does not exist or cannot be converted to the requested domain
    * and data type. */
   std::unique_ptr<blender::fn::GVArray> attribute_try_get_for_read(
-      const blender::StringRef attribute_name,
+      const blender::bke::AttributeIDRef &attribute_id,
       const AttributeDomain domain,
       const CustomDataType data_type) const;
 
@@ -150,18 +151,18 @@ class GeometryComponent {
    * left unchanged. Returns null when the attribute does not exist or cannot be adapted to the
    * requested domain. */
   std::unique_ptr<blender::fn::GVArray> attribute_try_get_for_read(
-      const blender::StringRef attribute_name, const AttributeDomain domain) const;
+      const blender::bke::AttributeIDRef &attribute_id, const AttributeDomain domain) const;
 
   /* Get a virtual array to read data of an attribute with the given data type. The domain is
    * left unchanged. Returns null when the attribute does not exist or cannot be converted to the
    * requested data type. */
   blender::bke::ReadAttributeLookup attribute_try_get_for_read(
-      const blender::StringRef attribute_name, const CustomDataType data_type) const;
+      const blender::bke::AttributeIDRef &attribute_id, const CustomDataType data_type) const;
 
   /* Get a virtual array to read the data of an attribute. If that is not possible, the returned
    * virtual array will contain a default value. This never returns null. */
   std::unique_ptr<blender::fn::GVArray> attribute_get_for_read(
-      const blender::StringRef attribute_name,
+      const blender::bke::AttributeIDRef &attribute_id,
       const AttributeDomain domain,
       const CustomDataType data_type,
       const void *default_value = nullptr) const;
@@ -169,14 +170,15 @@ class GeometryComponent {
   /* Should be used instead of the method above when the requested data type is known at compile
    * time for better type safety. */
   template<typename T>
-  blender::fn::GVArray_Typed<T> attribute_get_for_read(const blender::StringRef attribute_name,
-                                                       const AttributeDomain domain,
-                                                       const T &default_value) const
+  blender::fn::GVArray_Typed<T> attribute_get_for_read(
+      const blender::bke::AttributeIDRef &attribute_id,
+      const AttributeDomain domain,
+      const T &default_value) const
   {
     const blender::fn::CPPType &cpp_type = blender::fn::CPPType::get<T>();
     const CustomDataType type = blender::bke::cpp_type_to_custom_data_type(cpp_type);
     std::unique_ptr varray = this->attribute_get_for_read(
-        attribute_name, domain, type, &default_value);
+        attribute_id, domain, type, &default_value);
     return blender::fn::GVArray_Typed<T>(std::move(varray));
   }
 
@@ -191,7 +193,7 @@ class GeometryComponent {
    *   is created that will overwrite the existing attribute in the end.
    */
   blender::bke::OutputAttribute attribute_try_get_for_output(
-      const blender::StringRef attribute_name,
+      const blender::bke::AttributeIDRef &attribute_id,
       const AttributeDomain domain,
       const CustomDataType data_type,
       const void *default_value = nullptr);
@@ -200,28 +202,30 @@ class GeometryComponent {
    * attributes are not read, i.e. the attribute is used only for output. Since values are not read
    * from this attribute, no default value is necessary. */
   blender::bke::OutputAttribute attribute_try_get_for_output_only(
-      const blender::StringRef attribute_name,
+      const blender::bke::AttributeIDRef &attribute_id,
       const AttributeDomain domain,
       const CustomDataType data_type);
 
   /* Statically typed method corresponding to the equally named generic one. */
   template<typename T>
   blender::bke::OutputAttribute_Typed<T> attribute_try_get_for_output(
-      const blender::StringRef attribute_name, const AttributeDomain domain, const T default_value)
+      const blender::bke::AttributeIDRef &attribute_id,
+      const AttributeDomain domain,
+      const T default_value)
   {
     const blender::fn::CPPType &cpp_type = blender::fn::CPPType::get<T>();
     const CustomDataType data_type = blender::bke::cpp_type_to_custom_data_type(cpp_type);
-    return this->attribute_try_get_for_output(attribute_name, domain, data_type, &default_value);
+    return this->attribute_try_get_for_output(attribute_id, domain, data_type, &default_value);
   }
 
   /* Statically typed method corresponding to the equally named generic one. */
   template<typename T>
   blender::bke::OutputAttribute_Typed<T> attribute_try_get_for_output_only(
-      const blender::StringRef attribute_name, const AttributeDomain domain)
+      const blender::bke::AttributeIDRef &attribute_id, const AttributeDomain domain)
   {
     const blender::fn::CPPType &cpp_type = blender::fn::CPPType::get<T>();
     const CustomDataType data_type = blender::bke::cpp_type_to_custom_data_type(cpp_type);
-    return this->attribute_try_get_for_output_only(attribute_name, domain, data_type);
+    return this->attribute_try_get_for_output_only(attribute_id, domain, data_type);
   }
 
  private:

source/blender/blenkernel/BKE_geometry_set_instances.hh

@@ -59,9 +59,10 @@ struct AttributeKind {
  * will contain the highest complexity data type and the highest priority domain among every
  * attribute with the given name on all of the input components.
  */
-void geometry_set_gather_instances_attribute_info(Span<GeometryInstanceGroup> set_groups,
-                                                  Span<GeometryComponentType> component_types,
-                                                  const Set<std::string> &ignored_attributes,
-                                                  Map<std::string, AttributeKind> &r_attributes);
+void geometry_set_gather_instances_attribute_info(
+    Span<GeometryInstanceGroup> set_groups,
+    Span<GeometryComponentType> component_types,
+    const Set<std::string> &ignored_attributes,
+    Map<AttributeIDRef, AttributeKind> &r_attributes);
 
 }  // namespace blender::bke

source/blender/blenkernel/CMakeLists.txt

@@ -76,6 +76,7 @@ set(SRC
   intern/anim_path.c
   intern/anim_sys.c
   intern/anim_visualization.c
+  intern/anonymous_attribute.cc
   intern/appdir.c
   intern/armature.c
   intern/armature_selection.cc
@@ -295,6 +296,8 @@ set(SRC
   BKE_anim_path.h
   BKE_anim_visualization.h
   BKE_animsys.h
+  BKE_anonymous_attribute.h
+  BKE_anonymous_attribute.hh
   BKE_appdir.h
   BKE_armature.h
   BKE_armature.hh

source/blender/blenkernel/intern/anonymous_attribute.cc

@@ -0,0 +1,92 @@
+/*
+ * 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
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "BKE_anonymous_attribute.hh"
+
+using namespace blender::bke;
+
+struct AnonymousAttributeID {
+  mutable std::atomic<int> refcount_weak = 0;
+  mutable std::atomic<int> refcount_strong = 0;
+  std::string debug_name;
+  std::string internal_name;
+};
+
+static std::string get_new_internal_name()
+{
+  static std::atomic<int> index = 0;
+  const int next_index = index.fetch_add(1);
+  return "anonymous_attribute_" + std::to_string(next_index);
+}
+
+AnonymousAttributeID *BKE_anonymous_attribute_id_new_weak(const char *debug_name)
+{
+  AnonymousAttributeID *anonymous_id = new AnonymousAttributeID();
+  anonymous_id->debug_name = debug_name;
+  anonymous_id->internal_name = get_new_internal_name();
+  anonymous_id->refcount_weak.store(1);
+  return anonymous_id;
+}
+
+AnonymousAttributeID *BKE_anonymous_attribute_id_new_strong(const char *debug_name)
+{
+  AnonymousAttributeID *anonymous_id = new AnonymousAttributeID();
+  anonymous_id->debug_name = debug_name;
+  anonymous_id->internal_name = get_new_internal_name();
+  anonymous_id->refcount_weak.store(1);
+  anonymous_id->refcount_strong.store(1);
+  return anonymous_id;
+}
+
+bool BKE_anonymous_attribute_id_has_strong_references(const AnonymousAttributeID *anonymous_id)
+{
+  return anonymous_id->refcount_strong.load() >= 1;
+}
+
+void BKE_anonymous_attribute_id_increment_weak(const AnonymousAttributeID *anonymous_id)
+{
+  anonymous_id->refcount_weak.fetch_add(1);
+}
+
+void BKE_anonymous_attribute_id_increment_strong(const AnonymousAttributeID *anonymous_id)
+{
+  anonymous_id->refcount_weak.fetch_add(1);
+  anonymous_id->refcount_strong.fetch_add(1);
+}
+
+void BKE_anonymous_attribute_id_decrement_weak(const AnonymousAttributeID *anonymous_id)
+{
+  const int new_refcount = anonymous_id->refcount_weak.fetch_sub(1) - 1;
+  if (new_refcount == 0) {
+    delete anonymous_id;
+  }
+}
+
+void BKE_anonymous_attribute_id_decrement_strong(const AnonymousAttributeID *anonymous_id)
+{
+  anonymous_id->refcount_strong.fetch_sub(1);
+  BKE_anonymous_attribute_id_decrement_weak(anonymous_id);
+}
+
+const char *BKE_anonymous_attribute_id_debug_name(const AnonymousAttributeID *anonymous_id)
+{
+  return anonymous_id->debug_name.c_str();
+}
+
+const char *BKE_anonymous_attribute_id_internal_name(const AnonymousAttributeID *anonymous_id)
+{
+  return anonymous_id->internal_name.c_str();
+}

source/blender/blenkernel/intern/attribute_access.cc

@@ -334,8 +334,20 @@ bool BuiltinCustomDataLayerProvider::exists(const GeometryComponent &component)
   return data != nullptr;
 }
 
+static bool custom_data_layer_matches_attribute_id(const CustomDataLayer &layer,
+                                                   const AttributeIDRef &attribute_id)
+{
+  if (!attribute_id) {
+    return false;
+  }
+  if (attribute_id.is_anonymous()) {
+    return layer.anonymous_id == &attribute_id.anonymous_id();
+  }
+  return layer.name == attribute_id.name();
+}
+
 ReadAttributeLookup CustomDataAttributeProvider::try_get_for_read(
-    const GeometryComponent &component, const StringRef attribute_name) const
+    const GeometryComponent &component, const AttributeIDRef &attribute_id) const
 {
   const CustomData *custom_data = custom_data_access_.get_const_custom_data(component);
   if (custom_data == nullptr) {
@@ -343,7 +355,7 @@ ReadAttributeLookup CustomDataAttributeProvider::try_get_for_read(
   }
   const int domain_size = component.attribute_domain_size(domain_);
   for (const CustomDataLayer &layer : Span(custom_data->layers, custom_data->totlayer)) {
-    if (layer.name != attribute_name) {
+    if (!custom_data_layer_matches_attribute_id(layer, attribute_id)) {
       continue;
     }
     const CustomDataType data_type = (CustomDataType)layer.type;
@@ -368,7 +380,7 @@ ReadAttributeLookup CustomDataAttributeProvider::try_get_for_read(
 }
 
 WriteAttributeLookup CustomDataAttributeProvider::try_get_for_write(
-    GeometryComponent &component, const StringRef attribute_name) const
+    GeometryComponent &component, const AttributeIDRef &attribute_id) const
 {
   CustomData *custom_data = custom_data_access_.get_custom_data(component);
   if (custom_data == nullptr) {
@@ -376,10 +388,17 @@ WriteAttributeLookup CustomDataAttributeProvider::try_get_for_write(
   }
   const int domain_size = component.attribute_domain_size(domain_);
   for (CustomDataLayer &layer : MutableSpan(custom_data->layers, custom_data->totlayer)) {
-    if (layer.name != attribute_name) {
+    if (!custom_data_layer_matches_attribute_id(layer, attribute_id)) {
       continue;
     }
-    CustomData_duplicate_referenced_layer_named(custom_data, layer.type, layer.name, domain_size);
+    if (attribute_id.is_named()) {
+      CustomData_duplicate_referenced_layer_named(
+          custom_data, layer.type, layer.name, domain_size);
+    }
+    else {
+      CustomData_duplicate_referenced_layer_anonymous(
+          custom_data, layer.type, &attribute_id.anonymous_id(), domain_size);
+    }
     const CustomDataType data_type = (CustomDataType)layer.type;
     switch (data_type) {
       case CD_PROP_FLOAT:
@@ -402,7 +421,7 @@ WriteAttributeLookup CustomDataAttributeProvider::try_get_for_write(
 }
 
 bool CustomDataAttributeProvider::try_delete(GeometryComponent &component,
-                                             const StringRef attribute_name) const
+                                             const AttributeIDRef &attribute_id) const
 {
   CustomData *custom_data = custom_data_access_.get_custom_data(component);
   if (custom_data == nullptr) {
@@ -411,7 +430,8 @@ bool CustomDataAttributeProvider::try_delete(GeometryComponent &component,
   const int domain_size = component.attribute_domain_size(domain_);
   for (const int i : IndexRange(custom_data->totlayer)) {
     const CustomDataLayer &layer = custom_data->layers[i];
-    if (this->type_is_supported((CustomDataType)layer.type) && layer.name == attribute_name) {
+    if (this->type_is_supported((CustomDataType)layer.type) &&
+        custom_data_layer_matches_attribute_id(layer, attribute_id)) {
       CustomData_free_layer(custom_data, layer.type, domain_size, i);
       return true;
     }
@@ -419,24 +439,39 @@ bool CustomDataAttributeProvider::try_delete(GeometryComponent &component,
   return false;
 }
 
-static bool add_named_custom_data_layer_from_attribute_init(const StringRef attribute_name,
-                                                            CustomData &custom_data,
-                                                            const CustomDataType data_type,
-                                                            const int domain_size,
-                                                            const AttributeInit &initializer)
+static void *add_generic_custom_data_layer(CustomData &custom_data,
+                                           const CustomDataType data_type,
+                                           const eCDAllocType alloctype,
+                                           void *layer_data,
+                                           const int domain_size,
+                                           const AttributeIDRef &attribute_id)
 {
-  char attribute_name_c[MAX_NAME];
-  attribute_name.copy(attribute_name_c);
+  if (attribute_id.is_named()) {
+    char attribute_name_c[MAX_NAME];
+    attribute_id.name().copy(attribute_name_c);
+    return CustomData_add_layer_named(
+        &custom_data, data_type, CD_DEFAULT, nullptr, domain_size, attribute_name_c);
+  }
+  const AnonymousAttributeID &anonymous_id = attribute_id.anonymous_id();
+  return CustomData_add_layer_anonymous(
+      &custom_data, data_type, alloctype, layer_data, domain_size, &anonymous_id);
+}
 
+static bool add_custom_data_layer_from_attribute_init(const AttributeIDRef &attribute_id,
+                                                      CustomData &custom_data,
+                                                      const CustomDataType data_type,
+                                                      const int domain_size,
+                                                      const AttributeInit &initializer)
+{
   switch (initializer.type) {
     case AttributeInit::Type::Default: {
-      void *data = CustomData_add_layer_named(
-          &custom_data, data_type, CD_DEFAULT, nullptr, domain_size, attribute_name_c);
+      void *data = add_generic_custom_data_layer(
+          custom_data, data_type, CD_DEFAULT, nullptr, domain_size, attribute_id);
       return data != nullptr;
     }
     case AttributeInit::Type::VArray: {
-      void *data = CustomData_add_layer_named(
-          &custom_data, data_type, CD_DEFAULT, nullptr, domain_size, attribute_name_c);
+      void *data = add_generic_custom_data_layer(
+          custom_data, data_type, CD_DEFAULT, nullptr, domain_size, attribute_id);
       if (data == nullptr) {
         return false;
       }
@@ -446,8 +481,8 @@ static bool add_named_custom_data_layer_from_attribute_init(const StringRef attr
     }
     case AttributeInit::Type::MoveArray: {
       void *source_data = static_cast<const AttributeInitMove &>(initializer).data;
-      void *data = CustomData_add_layer_named(
-          &custom_data, data_type, CD_ASSIGN, source_data, domain_size, attribute_name_c);
+      void *data = add_generic_custom_data_layer(
+          custom_data, data_type, CD_ASSIGN, source_data, domain_size, attribute_id);
       if (data == nullptr) {
         MEM_freeN(source_data);
         return false;
@@ -461,7 +496,7 @@ static bool add_named_custom_data_layer_from_attribute_init(const StringRef attr
 }
 
 bool CustomDataAttributeProvider::try_create(GeometryComponent &component,
-                                             const StringRef attribute_name,
+                                             const AttributeIDRef &attribute_id,
                                              const AttributeDomain domain,
                                              const CustomDataType data_type,
                                              const AttributeInit &initializer) const
@@ -477,13 +512,13 @@ bool CustomDataAttributeProvider::try_create(GeometryComponent &component,
     return false;
   }
   for (const CustomDataLayer &layer : Span(custom_data->layers, custom_data->totlayer)) {
-    if (layer.name == attribute_name) {
+    if (custom_data_layer_matches_attribute_id(layer, attribute_id)) {
       return false;
     }
   }
   const int domain_size = component.attribute_domain_size(domain_);
-  add_named_custom_data_layer_from_attribute_init(
-      attribute_name, *custom_data, data_type, domain_size, initializer);
+  add_custom_data_layer_from_attribute_init(
+      attribute_id, *custom_data, data_type, domain_size, initializer);
   return true;
 }
 
@@ -498,7 +533,14 @@ bool CustomDataAttributeProvider::foreach_attribute(const GeometryComponent &com
     const CustomDataType data_type = (CustomDataType)layer.type;
     if (this->type_is_supported(data_type)) {
       AttributeMetaData meta_data{domain_, data_type};
-      if (!callback(layer.name, meta_data)) {
+      AttributeIDRef attribute_id;
+      if (layer.anonymous_id != nullptr) {
+        attribute_id = layer.anonymous_id;
+      }
+      else {
+        attribute_id = layer.name;
+      }
+      if (!callback(attribute_id, meta_data)) {
         return false;
       }
     }
@@ -507,7 +549,7 @@ bool CustomDataAttributeProvider::foreach_attribute(const GeometryComponent &com
 }
 
 ReadAttributeLookup NamedLegacyCustomDataProvider::try_get_for_read(
-    const GeometryComponent &component, const StringRef attribute_name) const
+    const GeometryComponent &component, const AttributeIDRef &attribute_id) const
 {
   const CustomData *custom_data = custom_data_access_.get_const_custom_data(component);
   if (custom_data == nullptr) {
@@ -515,7 +557,7 @@ ReadAttributeLookup NamedLegacyCustomDataProvider::try_get_for_read(
   }
   for (const CustomDataLayer &layer : Span(custom_data->layers, custom_data->totlayer)) {
     if (layer.type == stored_type_) {
-      if (layer.name == attribute_name) {
+      if (custom_data_layer_matches_attribute_id(layer, attribute_id)) {
         const int domain_size = component.attribute_domain_size(domain_);
         return {as_read_attribute_(layer.data, domain_size), domain_};
       }
@@ -525,7 +567,7 @@ ReadAttributeLookup NamedLegacyCustomDataProvider::try_get_for_read(
 }
 
 WriteAttributeLookup NamedLegacyCustomDataProvider::try_get_for_write(
-    GeometryComponent &component, const StringRef attribute_name) const
+    GeometryComponent &component, const AttributeIDRef &attribute_id) const
 {
   CustomData *custom_data = custom_data_access_.get_custom_data(component);
   if (custom_data == nullptr) {
@@ -533,7 +575,7 @@ WriteAttributeLookup NamedLegacyCustomDataProvider::try_get_for_write(
   }
   for (CustomDataLayer &layer : MutableSpan(custom_data->layers, custom_data->totlayer)) {
     if (layer.type == stored_type_) {
-      if (layer.name == attribute_name) {
+      if (custom_data_layer_matches_attribute_id(layer, attribute_id)) {
         const int domain_size = component.attribute_domain_size(domain_);
         void *data_old = layer.data;
         void *data_new = CustomData_duplicate_referenced_layer_named(
@@ -549,7 +591,7 @@ WriteAttributeLookup NamedLegacyCustomDataProvider::try_get_for_write(
 }
 
 bool NamedLegacyCustomDataProvider::try_delete(GeometryComponent &component,
-                                               const StringRef attribute_name) const
+                                               const AttributeIDRef &attribute_id) const
 {
   CustomData *custom_data = custom_data_access_.get_custom_data(component);
   if (custom_data == nullptr) {
@@ -558,7 +600,7 @@ bool NamedLegacyCustomDataProvider::try_delete(GeometryComponent &component,
   for (const int i : IndexRange(custom_data->totlayer)) {
     const CustomDataLayer &layer = custom_data->layers[i];
     if (layer.type == stored_type_) {
-      if (layer.name == attribute_name) {
+      if (custom_data_layer_matches_attribute_id(layer, attribute_id)) {
         const int domain_size = component.attribute_domain_size(domain_);
         CustomData_free_layer(custom_data, stored_type_, domain_size, i);
         custom_data_access_.update_custom_data_pointers(component);
@@ -627,11 +669,11 @@ CustomDataAttributes &CustomDataAttributes::operator=(const CustomDataAttributes
   return *this;
 }
 
-std::optional<GSpan> CustomDataAttributes::get_for_read(const StringRef name) const
+std::optional<GSpan> CustomDataAttributes::get_for_read(const AttributeIDRef &attribute_id) const
 {
   BLI_assert(size_ != 0);
   for (const CustomDataLayer &layer : Span(data.layers, data.totlayer)) {
-    if (layer.name == name) {
+    if (custom_data_layer_matches_attribute_id(layer, attribute_id)) {
       const CPPType *cpp_type = custom_data_type_to_cpp_type((CustomDataType)layer.type);
       BLI_assert(cpp_type != nullptr);
       return GSpan(*cpp_type, layer.data, size_);
@@ -645,13 +687,13 @@ std::optional<GSpan> CustomDataAttributes::get_for_read(const StringRef name) co
  * value if the attribute doesn't exist. If no default value is provided, the default value for the
  * type will be used.
  */
-GVArrayPtr CustomDataAttributes::get_for_read(const StringRef name,
+GVArrayPtr CustomDataAttributes::get_for_read(const AttributeIDRef &attribute_id,
                                               const CustomDataType data_type,
                                               const void *default_value) const
 {
   const CPPType *type = blender::bke::custom_data_type_to_cpp_type(data_type);
 
-  std::optional<GSpan> attribute = this->get_for_read(name);
+  std::optional<GSpan> attribute = this->get_for_read(attribute_id);
   if (!attribute) {
     const int domain_size = this->size_;
     return std::make_unique<GVArray_For_SingleValue>(
@@ -666,12 +708,12 @@ GVArrayPtr CustomDataAttributes::get_for_read(const StringRef name,
   return conversions.try_convert(std::make_unique<GVArray_For_GSpan>(*attribute), *type);
 }
 
-std::optional<GMutableSpan> CustomDataAttributes::get_for_write(const StringRef name)
+std::optional<GMutableSpan> CustomDataAttributes::get_for_write(const AttributeIDRef &attribute_id)
 {
   /* If this assert hits, it most likely means that #reallocate was not called at some point. */
   BLI_assert(size_ != 0);
   for (CustomDataLayer &layer : MutableSpan(data.layers, data.totlayer)) {
-    if (layer.name == name) {
+    if (custom_data_layer_matches_attribute_id(layer, attribute_id)) {
       const CPPType *cpp_type = custom_data_type_to_cpp_type((CustomDataType)layer.type);
       BLI_assert(cpp_type != nullptr);
       return GMutableSpan(*cpp_type, layer.data, size_);
@@ -680,30 +722,29 @@ std::optional<GMutableSpan> CustomDataAttributes::get_for_write(const StringRef
   return {};
 }
 
-bool CustomDataAttributes::create(const StringRef name, const CustomDataType data_type)
+bool CustomDataAttributes::create(const AttributeIDRef &attribute_id,
+                                  const CustomDataType data_type)
 {
-  char name_c[MAX_NAME];
-  name.copy(name_c);
-  void *result = CustomData_add_layer_named(&data, data_type, CD_DEFAULT, nullptr, size_, name_c);
+  void *result = add_generic_custom_data_layer(
+      data, data_type, CD_DEFAULT, nullptr, size_, attribute_id);
   return result != nullptr;
 }
 
-bool CustomDataAttributes::create_by_move(const blender::StringRef name,
+bool CustomDataAttributes::create_by_move(const blender::bke::AttributeIDRef &attribute_id,
                                           const CustomDataType data_type,
                                           void *buffer)
 {
-  char name_c[MAX_NAME];
-  name.copy(name_c);
-  void *result = CustomData_add_layer_named(&data, data_type, CD_ASSIGN, buffer, size_, name_c);
+  void *result = add_generic_custom_data_layer(
+      data, data_type, CD_ASSIGN, buffer, size_, attribute_id);
   return result != nullptr;
 }
 
-bool CustomDataAttributes::remove(const blender::StringRef name)
+bool CustomDataAttributes::remove(const blender::bke::AttributeIDRef &attribute_id)
 {
   bool result = false;
   for (const int i : IndexRange(data.totlayer)) {
     const CustomDataLayer &layer = data.layers[i];
-    if (layer.name == name) {
+    if (custom_data_layer_matches_attribute_id(layer, attribute_id)) {
       CustomData_free_layer(&data, layer.type, size_, i);
       result = true;
     }
@@ -722,7 +763,14 @@ bool CustomDataAttributes::foreach_attribute(const AttributeForeachCallback call
 {
   for (const CustomDataLayer &layer : Span(data.layers, data.totlayer)) {
     AttributeMetaData meta_data{domain, (CustomDataType)layer.type};
-    if (!callback(layer.name, meta_data)) {
+    AttributeIDRef attribute_id;
+    if (layer.anonymous_id != nullptr) {
+      attribute_id = layer.anonymous_id;
+    }
+    else {
+      attribute_id = layer.name;
+    }
+    if (!callback(attribute_id, meta_data)) {
       return false;
     }
   }
@@ -766,21 +814,23 @@ bool GeometryComponent::attribute_is_builtin(const blender::StringRef attribute_
 }
 
 blender::bke::ReadAttributeLookup GeometryComponent::attribute_try_get_for_read(
-    const StringRef attribute_name) const
+    const blender::bke::AttributeIDRef &attribute_id) const
 {
   using namespace blender::bke;
   const ComponentAttributeProviders *providers = this->get_attribute_providers();
   if (providers == nullptr) {
     return {};
   }
-  const BuiltinAttributeProvider *builtin_provider =
-      providers->builtin_attribute_providers().lookup_default_as(attribute_name, nullptr);
-  if (builtin_provider != nullptr) {
-    return {builtin_provider->try_get_for_read(*this), builtin_provider->domain()};
+  if (attribute_id.is_named()) {
+    const BuiltinAttributeProvider *builtin_provider =
+        providers->builtin_attribute_providers().lookup_default_as(attribute_id.name(), nullptr);
+    if (builtin_provider != nullptr) {
+      return {builtin_provider->try_get_for_read(*this), builtin_provider->domain()};
+    }
   }
   for (const DynamicAttributesProvider *dynamic_provider :
        providers->dynamic_attribute_providers()) {
-    ReadAttributeLookup attribute = dynamic_provider->try_get_for_read(*this, attribute_name);
+    ReadAttributeLookup attribute = dynamic_provider->try_get_for_read(*this, attribute_id);
     if (attribute) {
       return attribute;
     }
@@ -800,21 +850,23 @@ std::unique_ptr<blender::fn::GVArray> GeometryComponent::attribute_try_adapt_dom
 }
 
 blender::bke::WriteAttributeLookup GeometryComponent::attribute_try_get_for_write(
-    const StringRef attribute_name)
+    const blender::bke::AttributeIDRef &attribute_id)
 {
   using namespace blender::bke;
   const ComponentAttributeProviders *providers = this->get_attribute_providers();
   if (providers == nullptr) {
     return {};
   }
-  const BuiltinAttributeProvider *builtin_provider =
-      providers->builtin_attribute_providers().lookup_default_as(attribute_name, nullptr);
-  if (builtin_provider != nullptr) {
-    return {builtin_provider->try_get_for_write(*this), builtin_provider->domain()};
+  if (attribute_id.is_named()) {
+    const BuiltinAttributeProvider *builtin_provider =
+        providers->builtin_attribute_providers().lookup_default_as(attribute_id.name(), nullptr);
+    if (builtin_provider != nullptr) {
+      return {builtin_provider->try_get_for_write(*this), builtin_provider->domain()};
+    }
   }
   for (const DynamicAttributesProvider *dynamic_provider :
        providers->dynamic_attribute_providers()) {
-    WriteAttributeLookup attribute = dynamic_provider->try_get_for_write(*this, attribute_name);
+    WriteAttributeLookup attribute = dynamic_provider->try_get_for_write(*this, attribute_id);
     if (attribute) {
       return attribute;
     }
@@ -822,53 +874,57 @@ blender::bke::WriteAttributeLookup GeometryComponent::attribute_try_get_for_writ
   return {};
 }
 
-bool GeometryComponent::attribute_try_delete(const StringRef attribute_name)
+bool GeometryComponent::attribute_try_delete(const blender::bke::AttributeIDRef &attribute_id)
 {
   using namespace blender::bke;
   const ComponentAttributeProviders *providers = this->get_attribute_providers();
   if (providers == nullptr) {
     return {};
   }
-  const BuiltinAttributeProvider *builtin_provider =
-      providers->builtin_attribute_providers().lookup_default_as(attribute_name, nullptr);
-  if (builtin_provider != nullptr) {
-    return builtin_provider->try_delete(*this);
+  if (attribute_id.is_named()) {
+    const BuiltinAttributeProvider *builtin_provider =
+        providers->builtin_attribute_providers().lookup_default_as(attribute_id.name(), nullptr);
+    if (builtin_provider != nullptr) {
+      return builtin_provider->try_delete(*this);
+    }
   }
   bool success = false;
   for (const DynamicAttributesProvider *dynamic_provider :
        providers->dynamic_attribute_providers()) {
-    success = dynamic_provider->try_delete(*this, attribute_name) || success;
+    success = dynamic_provider->try_delete(*this, attribute_id) || success;
   }
   return success;
 }
 
-bool GeometryComponent::attribute_try_create(const StringRef attribute_name,
+bool GeometryComponent::attribute_try_create(const blender::bke::AttributeIDRef &attribute_id,
                                              const AttributeDomain domain,
                                              const CustomDataType data_type,
                                              const AttributeInit &initializer)
 {
   using namespace blender::bke;
-  if (attribute_name.is_empty()) {
+  if (!attribute_id) {
     return false;
   }
   const ComponentAttributeProviders *providers = this->get_attribute_providers();
   if (providers == nullptr) {
     return false;
   }
-  const BuiltinAttributeProvider *builtin_provider =
-      providers->builtin_attribute_providers().lookup_default_as(attribute_name, nullptr);
-  if (builtin_provider != nullptr) {
-    if (builtin_provider->domain() != domain) {
-      return false;
+  if (attribute_id.is_named()) {
+    const BuiltinAttributeProvider *builtin_provider =
+        providers->builtin_attribute_providers().lookup_default_as(attribute_id.name(), nullptr);
+    if (builtin_provider != nullptr) {
+      if (builtin_provider->domain() != domain) {
+        return false;
+      }
+      if (builtin_provider->data_type() != data_type) {
+        return false;
+      }
+      return builtin_provider->try_create(*this, initializer);
     }
-    if (builtin_provider->data_type() != data_type) {
-      return false;
-    }
-    return builtin_provider->try_create(*this, initializer);
   }
   for (const DynamicAttributesProvider *dynamic_provider :
        providers->dynamic_attribute_providers()) {
-    if (dynamic_provider->try_create(*this, attribute_name, domain, data_type, initializer)) {
+    if (dynamic_provider->try_create(*this, attribute_id, domain, data_type, initializer)) {
       return true;
     }
   }
@@ -894,11 +950,12 @@ bool GeometryComponent::attribute_try_create_builtin(const blender::StringRef at
   return builtin_provider->try_create(*this, initializer);
 }
 
-Set<std::string> GeometryComponent::attribute_names() const
+Set<blender::bke::AttributeIDRef> GeometryComponent::attribute_ids() const
 {
-  Set<std::string> attributes;
-  this->attribute_foreach([&](StringRefNull name, const AttributeMetaData &UNUSED(meta_data)) {
-    attributes.add(name);
+  Set<blender::bke::AttributeIDRef> attributes;
+  this->attribute_foreach([&](const blender::bke::AttributeIDRef &attribute_id,
+                              const AttributeMetaData &UNUSED(meta_data)) {
+    attributes.add(attribute_id);
     return true;
   });
   return attributes;
@@ -931,9 +988,9 @@ bool GeometryComponent::attribute_foreach(const AttributeForeachCallback callbac
   }
   for (const DynamicAttributesProvider *provider : providers->dynamic_attribute_providers()) {
     const bool continue_loop = provider->foreach_attribute(
-        *this, [&](StringRefNull name, const AttributeMetaData &meta_data) {
-          if (handled_attribute_names.add(name)) {
-            return callback(name, meta_data);
+        *this, [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+          if (attribute_id.is_anonymous() || handled_attribute_names.add(attribute_id.name())) {
+            return callback(attribute_id, meta_data);
           }
           return true;
         });
@@ -945,9 +1002,9 @@ bool GeometryComponent::attribute_foreach(const AttributeForeachCallback callbac
   return true;
 }
 
-bool GeometryComponent::attribute_exists(const blender::StringRef attribute_name) const
+bool GeometryComponent::attribute_exists(const blender::bke::AttributeIDRef &attribute_id) const
 {
-  blender::bke::ReadAttributeLookup attribute = this->attribute_try_get_for_read(attribute_name);
+  blender::bke::ReadAttributeLookup attribute = this->attribute_try_get_for_read(attribute_id);
   if (attribute) {
     return true;
   }
@@ -955,11 +1012,12 @@ bool GeometryComponent::attribute_exists(const blender::StringRef attribute_name
 }
 
 std::optional<AttributeMetaData> GeometryComponent::attribute_get_meta_data(
-    const StringRef attribute_name) const
+    const blender::bke::AttributeIDRef &attribute_id) const
 {
   std::optional<AttributeMetaData> result{std::nullopt};
-  this->attribute_foreach([&](StringRefNull name, const AttributeMetaData &meta_data) {
-    if (attribute_name == name) {
+  this->attribute_foreach([&](const blender::bke::AttributeIDRef &current_attribute_id,
+                              const AttributeMetaData &meta_data) {
+    if (attribute_id == current_attribute_id) {
       result = meta_data;
       return false;
     }
@@ -977,11 +1035,11 @@ static std::unique_ptr<blender::fn::GVArray> try_adapt_data_type(
 }
 
 std::unique_ptr<blender::fn::GVArray> GeometryComponent::attribute_try_get_for_read(
-    const StringRef attribute_name,
+    const blender::bke::AttributeIDRef &attribute_id,
     const AttributeDomain domain,
     const CustomDataType data_type) const
 {
-  blender::bke::ReadAttributeLookup attribute = this->attribute_try_get_for_read(attribute_name);
+  blender::bke::ReadAttributeLookup attribute = this->attribute_try_get_for_read(attribute_id);
   if (!attribute) {
     return {};
   }
@@ -1007,13 +1065,13 @@ std::unique_ptr<blender::fn::GVArray> GeometryComponent::attribute_try_get_for_r
 }
 
 std::unique_ptr<blender::bke::GVArray> GeometryComponent::attribute_try_get_for_read(
-    const StringRef attribute_name, const AttributeDomain domain) const
+    const blender::bke::AttributeIDRef &attribute_id, const AttributeDomain domain) const
 {
   if (!this->attribute_domain_supported(domain)) {
     return {};
   }
 
-  blender::bke::ReadAttributeLookup attribute = this->attribute_try_get_for_read(attribute_name);
+  blender::bke::ReadAttributeLookup attribute = this->attribute_try_get_for_read(attribute_id);
   if (!attribute) {
     return {};
   }
@@ -1026,9 +1084,9 @@ std::unique_ptr<blender::bke::GVArray> GeometryComponent::attribute_try_get_for_
 }
 
 blender::bke::ReadAttributeLookup GeometryComponent::attribute_try_get_for_read(
-    const blender::StringRef attribute_name, const CustomDataType data_type) const
+    const blender::bke::AttributeIDRef &attribute_id, const CustomDataType data_type) const
 {
-  blender::bke::ReadAttributeLookup attribute = this->attribute_try_get_for_read(attribute_name);
+  blender::bke::ReadAttributeLookup attribute = this->attribute_try_get_for_read(attribute_id);
   if (!attribute) {
     return {};
   }
@@ -1043,13 +1101,13 @@ blender::bke::ReadAttributeLookup GeometryComponent::attribute_try_get_for_read(
 }
 
 std::unique_ptr<blender::bke::GVArray> GeometryComponent::attribute_get_for_read(
-    const StringRef attribute_name,
+    const blender::bke::AttributeIDRef &attribute_id,
     const AttributeDomain domain,
     const CustomDataType data_type,
     const void *default_value) const
 {
   std::unique_ptr<blender::bke::GVArray> varray = this->attribute_try_get_for_read(
-      attribute_name, domain, data_type);
+      attribute_id, domain, data_type);
   if (varray) {
     return varray;
   }
@@ -1065,15 +1123,22 @@ class GVMutableAttribute_For_OutputAttribute
     : public blender::fn::GVMutableArray_For_GMutableSpan {
  public:
   GeometryComponent *component;
-  std::string final_name;
+  std::string attribute_name;
+  blender::bke::WeakAnonymousAttributeID anonymous_attribute_id;
 
   GVMutableAttribute_For_OutputAttribute(GMutableSpan data,
                                          GeometryComponent &component,
-                                         std::string final_name)
-      : blender::fn::GVMutableArray_For_GMutableSpan(data),
-        component(&component),
-        final_name(std::move(final_name))
+                                         const blender::bke::AttributeIDRef &attribute_id)
+      : blender::fn::GVMutableArray_For_GMutableSpan(data), component(&component)
   {
+    if (attribute_id.is_named()) {
+      this->attribute_name = attribute_id.name();
+    }
+    else {
+      const AnonymousAttributeID *anonymous_id = &attribute_id.anonymous_id();
+      BKE_anonymous_attribute_id_increment_weak(anonymous_id);
+      this->anonymous_attribute_id = blender::bke::WeakAnonymousAttributeID{anonymous_id};
+    }
   }
 
   ~GVMutableAttribute_For_OutputAttribute() override
@@ -1093,21 +1158,28 @@ static void save_output_attribute(blender::bke::OutputAttribute &output_attribut
       dynamic_cast<GVMutableAttribute_For_OutputAttribute &>(output_attribute.varray());
 
   GeometryComponent &component = *varray.component;
-  const StringRefNull name = varray.final_name;
+  AttributeIDRef attribute_id;
+  if (!varray.attribute_name.empty()) {
+    attribute_id = varray.attribute_name;
+  }
+  else {
+    attribute_id = varray.anonymous_attribute_id.extract();
+  }
   const AttributeDomain domain = output_attribute.domain();
   const CustomDataType data_type = output_attribute.custom_data_type();
   const CPPType &cpp_type = output_attribute.cpp_type();
 
-  component.attribute_try_delete(name);
-  if (!component.attribute_try_create(
-          varray.final_name, domain, data_type, AttributeInitDefault())) {
-    CLOG_WARN(&LOG,
-              "Could not create the '%s' attribute with type '%s'.",
-              name.c_str(),
-              cpp_type.name().c_str());
+  component.attribute_try_delete(attribute_id);
+  if (!component.attribute_try_create(attribute_id, domain, data_type, AttributeInitDefault())) {
+    if (!varray.attribute_name.empty()) {
+      CLOG_WARN(&LOG,
+                "Could not create the '%s' attribute with type '%s'.",
+                varray.attribute_name.c_str(),
+                cpp_type.name().c_str());
+    }
     return;
   }
-  WriteAttributeLookup write_attribute = component.attribute_try_get_for_write(name);
+  WriteAttributeLookup write_attribute = component.attribute_try_get_for_write(attribute_id);
   BUFFER_FOR_CPP_TYPE_VALUE(varray.type(), buffer);
   for (const int i : IndexRange(varray.size())) {
     varray.get(i, buffer);
@@ -1117,7 +1189,7 @@ static void save_output_attribute(blender::bke::OutputAttribute &output_attribut
 
 static blender::bke::OutputAttribute create_output_attribute(
     GeometryComponent &component,
-    const blender::StringRef attribute_name,
+    const blender::bke::AttributeIDRef &attribute_id,
     const AttributeDomain domain,
     const CustomDataType data_type,
     const bool ignore_old_values,
@@ -1127,7 +1199,7 @@ static blender::bke::OutputAttribute create_output_attribute(
   using namespace blender::fn;
   using namespace blender::bke;
 
-  if (attribute_name.is_empty()) {
+  if (!attribute_id) {
     return {};
   }
 
@@ -1135,7 +1207,8 @@ static blender::bke::OutputAttribute create_output_attribute(
   BLI_assert(cpp_type != nullptr);
   const nodes::DataTypeConversions &conversions = nodes::get_implicit_type_conversions();
 
-  if (component.attribute_is_builtin(attribute_name)) {
+  if (attribute_id.is_named() && component.attribute_is_builtin(attribute_id.name())) {
+    const StringRef attribute_name = attribute_id.name();
     WriteAttributeLookup attribute = component.attribute_try_get_for_write(attribute_name);
     if (!attribute) {
       if (default_value) {
@@ -1169,18 +1242,18 @@ static blender::bke::OutputAttribute create_output_attribute(
 
   const int domain_size = component.attribute_domain_size(domain);
 
-  WriteAttributeLookup attribute = component.attribute_try_get_for_write(attribute_name);
+  WriteAttributeLookup attribute = component.attribute_try_get_for_write(attribute_id);
   if (!attribute) {
     if (default_value) {
       const GVArray_For_SingleValueRef default_varray{*cpp_type, domain_size, default_value};
       component.attribute_try_create(
-          attribute_name, domain, data_type, AttributeInitVArray(&default_varray));
+          attribute_id, domain, data_type, AttributeInitVArray(&default_varray));
     }
     else {
-      component.attribute_try_create(attribute_name, domain, data_type, AttributeInitDefault());
+      component.attribute_try_create(attribute_id, domain, data_type, AttributeInitDefault());
     }
 
-    attribute = component.attribute_try_get_for_write(attribute_name);
+    attribute = component.attribute_try_get_for_write(attribute_id);
     if (!attribute) {
       /* Can't create the attribute. */
       return {};
@@ -1202,28 +1275,28 @@ static blender::bke::OutputAttribute create_output_attribute(
   else {
     /* Fill the temporary array with values from the existing attribute. */
     GVArrayPtr old_varray = component.attribute_get_for_read(
-        attribute_name, domain, data_type, default_value);
+        attribute_id, domain, data_type, default_value);
     old_varray->materialize_to_uninitialized(IndexRange(domain_size), data);
   }
   GVMutableArrayPtr varray = std::make_unique<GVMutableAttribute_For_OutputAttribute>(
-      GMutableSpan{*cpp_type, data, domain_size}, component, attribute_name);
+      GMutableSpan{*cpp_type, data, domain_size}, component, attribute_id);
 
   return OutputAttribute(std::move(varray), domain, save_output_attribute, true);
 }
 
 blender::bke::OutputAttribute GeometryComponent::attribute_try_get_for_output(
-    const StringRef attribute_name,
+    const blender::bke::AttributeIDRef &attribute_id,
     const AttributeDomain domain,
     const CustomDataType data_type,
     const void *default_value)
 {
-  return create_output_attribute(*this, attribute_name, domain, data_type, false, default_value);
+  return create_output_attribute(*this, attribute_id, domain, data_type, false, default_value);
 }
 
 blender::bke::OutputAttribute GeometryComponent::attribute_try_get_for_output_only(
-    const blender::StringRef attribute_name,
+    const blender::bke::AttributeIDRef &attribute_id,
     const AttributeDomain domain,
     const CustomDataType data_type)
 {
-  return create_output_attribute(*this, attribute_name, domain, data_type, true, nullptr);
+  return create_output_attribute(*this, attribute_id, domain, data_type, true, nullptr);
 }

source/blender/blenkernel/intern/attribute_access_intern.hh

@@ -116,12 +116,13 @@ class BuiltinAttributeProvider {
 class DynamicAttributesProvider {
  public:
   virtual ReadAttributeLookup try_get_for_read(const GeometryComponent &component,
-                                               const StringRef attribute_name) const = 0;
+                                               const AttributeIDRef &attribute_id) const = 0;
   virtual WriteAttributeLookup try_get_for_write(GeometryComponent &component,
-                                                 const StringRef attribute_name) const = 0;
-  virtual bool try_delete(GeometryComponent &component, const StringRef attribute_name) const = 0;
+                                                 const AttributeIDRef &attribute_id) const = 0;
+  virtual bool try_delete(GeometryComponent &component,
+                          const AttributeIDRef &attribute_id) const = 0;
   virtual bool try_create(GeometryComponent &UNUSED(component),
-                          const StringRef UNUSED(attribute_name),
+                          const AttributeIDRef &UNUSED(attribute_id),
                           const AttributeDomain UNUSED(domain),
                           const CustomDataType UNUSED(data_type),
                           const AttributeInit &UNUSED(initializer)) const
@@ -154,15 +155,15 @@ class CustomDataAttributeProvider final : public DynamicAttributesProvider {
   }
 
   ReadAttributeLookup try_get_for_read(const GeometryComponent &component,
-                                       const StringRef attribute_name) const final;
+                                       const AttributeIDRef &attribute_id) const final;
 
   WriteAttributeLookup try_get_for_write(GeometryComponent &component,
-                                         const StringRef attribute_name) const final;
+                                         const AttributeIDRef &attribute_id) const final;
 
-  bool try_delete(GeometryComponent &component, const StringRef attribute_name) const final;
+  bool try_delete(GeometryComponent &component, const AttributeIDRef &attribute_id) const final;
 
   bool try_create(GeometryComponent &component,
-                  const StringRef attribute_name,
+                  const AttributeIDRef &attribute_id,
                   const AttributeDomain domain,
                   const CustomDataType data_type,
                   const AttributeInit &initializer) const final;
@@ -231,10 +232,10 @@ class NamedLegacyCustomDataProvider final : public DynamicAttributesProvider {
   }
 
   ReadAttributeLookup try_get_for_read(const GeometryComponent &component,
-                                       const StringRef attribute_name) const final;
+                                       const AttributeIDRef &attribute_id) const final;
   WriteAttributeLookup try_get_for_write(GeometryComponent &component,
-                                         const StringRef attribute_name) const final;
-  bool try_delete(GeometryComponent &component, const StringRef attribute_name) const final;
+                                         const AttributeIDRef &attribute_id) const final;
+  bool try_delete(GeometryComponent &component, const AttributeIDRef &attribute_id) const final;
   bool foreach_attribute(const GeometryComponent &component,
                          const AttributeForeachCallback callback) const final;
   void foreach_domain(const FunctionRef<void(AttributeDomain)> callback) const final;

source/blender/blenkernel/intern/curve_eval.cc

@@ -25,6 +25,7 @@
 
 #include "DNA_curve_types.h"
 
+#include "BKE_anonymous_attribute.hh"
 #include "BKE_curve.h"
 #include "BKE_spline.hh"
 
@@ -330,13 +331,13 @@ void CurveEval::assert_valid_point_attributes() const
     return;
   }
   const int layer_len = splines_.first()->attributes.data.totlayer;
-  Map<StringRefNull, AttributeMetaData> map;
+  Map<blender::bke::AttributeIDRef, AttributeMetaData> map;
   for (const SplinePtr &spline : splines_) {
     BLI_assert(spline->attributes.data.totlayer == layer_len);
     spline->attributes.foreach_attribute(
-        [&](StringRefNull name, const AttributeMetaData &meta_data) {
+        [&](const blender::bke::AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
           map.add_or_modify(
-              name,
+              attribute_id,
               [&](AttributeMetaData *map_data) {
                 /* All unique attribute names should be added on the first spline. */
                 BLI_assert(spline == splines_.first());

source/blender/blenkernel/intern/customdata.c

@@ -46,6 +46,7 @@
 
 #include "BLT_translation.h"
 
+#include "BKE_anonymous_attribute.h"
 #include "BKE_customdata.h"
 #include "BKE_customdata_file.h"
 #include "BKE_deform.h"
@@ -2127,6 +2128,10 @@ bool CustomData_merge(const struct CustomData *source,
     if (flag & CD_FLAG_NOCOPY) {
       continue;
     }
+    if (layer->anonymous_id &&
+        !BKE_anonymous_attribute_id_has_strong_references(layer->anonymous_id)) {
+      continue;
+    }
     if (!(mask & CD_TYPE_AS_MASK(type))) {
       continue;
     }
@@ -2166,6 +2171,11 @@ bool CustomData_merge(const struct CustomData *source,
       newlayer->active_mask = lastmask;
       newlayer->flag |= flag & (CD_FLAG_EXTERNAL | CD_FLAG_IN_MEMORY);
       changed = true;
+
+      if (layer->anonymous_id != NULL) {
+        BKE_anonymous_attribute_id_increment_weak(layer->anonymous_id);
+        newlayer->anonymous_id = layer->anonymous_id;
+      }
     }
   }
 
@@ -2206,6 +2216,10 @@ static void customData_free_layer__internal(CustomDataLayer *layer, int totelem)
 {
   const LayerTypeInfo *typeInfo;
 
+  if (layer->anonymous_id != NULL) {
+    BKE_anonymous_attribute_id_decrement_weak(layer->anonymous_id);
+    layer->anonymous_id = NULL;
+  }
   if (!(layer->flag & CD_FLAG_NOFREE) && layer->data) {
     typeInfo = layerType_getInfo(layer->type);
 
@@ -2649,6 +2663,27 @@ void *CustomData_add_layer_named(CustomData *data,
   return NULL;
 }
 
+void *CustomData_add_layer_anonymous(struct CustomData *data,
+                                     int type,
+                                     eCDAllocType alloctype,
+                                     void *layerdata,
+                                     int totelem,
+                                     const AnonymousAttributeID *anonymous_id)
+{
+  const char *name = BKE_anonymous_attribute_id_internal_name(anonymous_id);
+  CustomDataLayer *layer = customData_add_layer__internal(
+      data, type, alloctype, layerdata, totelem, name);
+  CustomData_update_typemap(data);
+
+  if (layer == NULL) {
+    return NULL;
+  }
+
+  BKE_anonymous_attribute_id_increment_weak(anonymous_id);
+  layer->anonymous_id = anonymous_id;
+  return layer->data;
+}
+
 bool CustomData_free_layer(CustomData *data, int type, int totelem, int index)
 {
   const int index_first = CustomData_get_layer_index(data, type);
@@ -2812,6 +2847,20 @@ void *CustomData_duplicate_referenced_layer_named(CustomData *data,
   return customData_duplicate_referenced_layer_index(data, layer_index, totelem);
 }
 
+void *CustomData_duplicate_referenced_layer_anonymous(CustomData *data,
+                                                      const int type,
+                                                      const AnonymousAttributeID *anonymous_id,
+                                                      const int totelem)
+{
+  for (int i = 0; i < data->totlayer; i++) {
+    if (data->layers[i].anonymous_id == anonymous_id) {
+      return customData_duplicate_referenced_layer_index(data, i, totelem);
+    }
+  }
+  BLI_assert_unreachable();
+  return NULL;
+}
+
 void CustomData_duplicate_referenced_layers(CustomData *data, int totelem)
 {
   for (int i = 0; i < data->totlayer; i++) {
@@ -4244,7 +4293,8 @@ void CustomData_blend_write_prepare(CustomData *data,
 
   for (i = 0, j = 0; i < totlayer; i++) {
     CustomDataLayer *layer = &data->layers[i];
-    if (layer->flag & CD_FLAG_NOCOPY) { /* Layers with this flag set are not written to file. */
+    /* Layers with this flag set are not written to file. */
+    if ((layer->flag & CD_FLAG_NOCOPY) || layer->anonymous_id != NULL) {
       data->totlayer--;
       // CLOG_WARN(&LOG, "skipping layer %p (%s)", layer, layer->name);
     }

source/blender/blenkernel/intern/geometry_component_curve.cc

@@ -892,7 +892,7 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
 
  public:
   ReadAttributeLookup try_get_for_read(const GeometryComponent &component,
-                                       const StringRef attribute_name) const final
+                                       const AttributeIDRef &attribute_id) const final
   {
     const CurveEval *curve = get_curve_from_component_for_read(component);
     if (curve == nullptr || curve->splines().size() == 0) {
@@ -902,13 +902,13 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
     Span<SplinePtr> splines = curve->splines();
     Vector<GSpan> spans; /* GSpan has no default constructor. */
     spans.reserve(splines.size());
-    std::optional<GSpan> first_span = splines[0]->attributes.get_for_read(attribute_name);
+    std::optional<GSpan> first_span = splines[0]->attributes.get_for_read(attribute_id);
     if (!first_span) {
       return {};
     }
     spans.append(*first_span);
     for (const int i : IndexRange(1, splines.size() - 1)) {
-      std::optional<GSpan> span = splines[i]->attributes.get_for_read(attribute_name);
+      std::optional<GSpan> span = splines[i]->attributes.get_for_read(attribute_id);
       if (!span) {
         /* All splines should have the same set of data layers. It would be possible to recover
          * here and return partial data instead, but that would add a lot of complexity for a
@@ -945,7 +945,7 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
 
   /* This function is almost the same as #try_get_for_read, but without const. */
   WriteAttributeLookup try_get_for_write(GeometryComponent &component,
-                                         const StringRef attribute_name) const final
+                                         const AttributeIDRef &attribute_id) const final
   {
     CurveEval *curve = get_curve_from_component_for_write(component);
     if (curve == nullptr || curve->splines().size() == 0) {
@@ -955,13 +955,13 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
     MutableSpan<SplinePtr> splines = curve->splines();
     Vector<GMutableSpan> spans; /* GMutableSpan has no default constructor. */
     spans.reserve(splines.size());
-    std::optional<GMutableSpan> first_span = splines[0]->attributes.get_for_write(attribute_name);
+    std::optional<GMutableSpan> first_span = splines[0]->attributes.get_for_write(attribute_id);
     if (!first_span) {
       return {};
     }
     spans.append(*first_span);
     for (const int i : IndexRange(1, splines.size() - 1)) {
-      std::optional<GMutableSpan> span = splines[i]->attributes.get_for_write(attribute_name);
+      std::optional<GMutableSpan> span = splines[i]->attributes.get_for_write(attribute_id);
       if (!span) {
         /* All splines should have the same set of data layers. It would be possible to recover
          * here and return partial data instead, but that would add a lot of complexity for a
@@ -996,7 +996,7 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
     return attribute;
   }
 
-  bool try_delete(GeometryComponent &component, const StringRef attribute_name) const final
+  bool try_delete(GeometryComponent &component, const AttributeIDRef &attribute_id) const final
   {
     CurveEval *curve = get_curve_from_component_for_write(component);
     if (curve == nullptr) {
@@ -1006,7 +1006,7 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
     /* Reuse the boolean for all splines; we expect all splines to have the same attributes. */
     bool layer_freed = false;
     for (SplinePtr &spline : curve->splines()) {
-      layer_freed = spline->attributes.remove(attribute_name);
+      layer_freed = spline->attributes.remove(attribute_id);
     }
     return layer_freed;
   }
@@ -1034,7 +1034,7 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
   }
 
   bool try_create(GeometryComponent &component,
-                  const StringRef attribute_name,
+                  const AttributeIDRef &attribute_id,
                   const AttributeDomain domain,
                   const CustomDataType data_type,
                   const AttributeInit &initializer) const final
@@ -1053,7 +1053,7 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
     /* First check the one case that allows us to avoid copying the input data. */
     if (splines.size() == 1 && initializer.type == AttributeInit::Type::MoveArray) {
       void *source_data = static_cast<const AttributeInitMove &>(initializer).data;
-      if (!splines[0]->attributes.create_by_move(attribute_name, data_type, source_data)) {
+      if (!splines[0]->attributes.create_by_move(attribute_id, data_type, source_data)) {
         MEM_freeN(source_data);
         return false;
       }
@@ -1062,7 +1062,7 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
 
     /* Otherwise just create a custom data layer on each of the splines. */
     for (const int i : splines.index_range()) {
-      if (!splines[i]->attributes.create(attribute_name, data_type)) {
+      if (!splines[i]->attributes.create(attribute_id, data_type)) {
         /* If attribute creation fails on one of the splines, we cannot leave the custom data
          * layers in the previous splines around, so delete them before returning. However,
          * this is not an expected case. */
@@ -1076,7 +1076,7 @@ class DynamicPointAttributeProvider final : public DynamicAttributesProvider {
       return true;
     }
 
-    WriteAttributeLookup write_attribute = this->try_get_for_write(component, attribute_name);
+    WriteAttributeLookup write_attribute = this->try_get_for_write(component, attribute_id);
     /* We just created the attribute, it should exist. */
     BLI_assert(write_attribute);
 

source/blender/blenkernel/intern/geometry_component_mesh.cc

@@ -818,16 +818,20 @@ class VArray_For_VertexWeights final : public VArray<float> {
 class VertexGroupsAttributeProvider final : public DynamicAttributesProvider {
  public:
   ReadAttributeLookup try_get_for_read(const GeometryComponent &component,
-                                       const StringRef attribute_name) const final
+                                       const AttributeIDRef &attribute_id) const final
   {
     BLI_assert(component.type() == GEO_COMPONENT_TYPE_MESH);
+    if (!attribute_id.is_named()) {
+      return {};
+    }
     const MeshComponent &mesh_component = static_cast<const MeshComponent &>(component);
     const Mesh *mesh = mesh_component.get_for_read();
     if (mesh == nullptr) {
       return {};
     }
+    std::string name = attribute_id.name();
     const int vertex_group_index = BLI_findstringindex(
-        &mesh->vertex_group_names, attribute_name.data(), offsetof(bDeformGroup, name));
+        &mesh->vertex_group_names, name.c_str(), offsetof(bDeformGroup, name));
     if (vertex_group_index < 0) {
       return {};
     }
@@ -843,17 +847,21 @@ class VertexGroupsAttributeProvider final : public DynamicAttributesProvider {
   }
 
   WriteAttributeLookup try_get_for_write(GeometryComponent &component,
-                                         const StringRef attribute_name) const final
+                                         const AttributeIDRef &attribute_id) const final
   {
     BLI_assert(component.type() == GEO_COMPONENT_TYPE_MESH);
+    if (!attribute_id.is_named()) {
+      return {};
+    }
     MeshComponent &mesh_component = static_cast<MeshComponent &>(component);
     Mesh *mesh = mesh_component.get_for_write();
     if (mesh == nullptr) {
       return {};
     }
 
+    const std::string name = attribute_id.name();
     const int vertex_group_index = BLI_findstringindex(
-        &mesh->vertex_group_names, attribute_name.data(), offsetof(bDeformGroup, name));
+        &mesh->vertex_group_names, name.c_str(), offsetof(bDeformGroup, name));
     if (vertex_group_index < 0) {
       return {};
     }
@@ -872,17 +880,21 @@ class VertexGroupsAttributeProvider final : public DynamicAttributesProvider {
         ATTR_DOMAIN_POINT};
   }
 
-  bool try_delete(GeometryComponent &component, const StringRef attribute_name) const final
+  bool try_delete(GeometryComponent &component, const AttributeIDRef &attribute_id) const final
   {
     BLI_assert(component.type() == GEO_COMPONENT_TYPE_MESH);
+    if (!attribute_id.is_named()) {
+      return false;
+    }
     MeshComponent &mesh_component = static_cast<MeshComponent &>(component);
     Mesh *mesh = mesh_component.get_for_write();
     if (mesh == nullptr) {
       return true;
     }
 
+    const std::string name = attribute_id.name();
     const int vertex_group_index = BLI_findstringindex(
-        &mesh->vertex_group_names, attribute_name.data(), offsetof(bDeformGroup, name));
+        &mesh->vertex_group_names, name.c_str(), offsetof(bDeformGroup, name));
     if (vertex_group_index < 0) {
       return false;
     }

source/blender/blenkernel/intern/geometry_set_instances.cc

@@ -319,7 +319,7 @@ void geometry_set_instances_attribute_foreach(const GeometrySet &geometry_set,
 void geometry_set_gather_instances_attribute_info(Span<GeometryInstanceGroup> set_groups,
                                                   Span<GeometryComponentType> component_types,
                                                   const Set<std::string> &ignored_attributes,
-                                                  Map<std::string, AttributeKind> &r_attributes)
+                                                  Map<AttributeIDRef, AttributeKind> &r_attributes)
 {
   for (const GeometryInstanceGroup &set_group : set_groups) {
     const GeometrySet &set = set_group.geometry_set;
@@ -329,23 +329,24 @@ void geometry_set_gather_instances_attribute_info(Span<GeometryInstanceGroup> se
       }
       const GeometryComponent &component = *set.get_component_for_read(component_type);
 
-      component.attribute_foreach([&](StringRefNull name, const AttributeMetaData &meta_data) {
-        if (ignored_attributes.contains(name)) {
-          return true;
-        }
-        auto add_info = [&](AttributeKind *attribute_kind) {
-          attribute_kind->domain = meta_data.domain;
-          attribute_kind->data_type = meta_data.data_type;
-        };
-        auto modify_info = [&](AttributeKind *attribute_kind) {
-          attribute_kind->domain = meta_data.domain; /* TODO: Use highest priority domain. */
-          attribute_kind->data_type = bke::attribute_data_type_highest_complexity(
-              {attribute_kind->data_type, meta_data.data_type});
-        };
+      component.attribute_foreach(
+          [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+            if (attribute_id.is_named() && ignored_attributes.contains(attribute_id.name())) {
+              return true;
+            }
+            auto add_info = [&](AttributeKind *attribute_kind) {
+              attribute_kind->domain = meta_data.domain;
+              attribute_kind->data_type = meta_data.data_type;
+            };
+            auto modify_info = [&](AttributeKind *attribute_kind) {
+              attribute_kind->domain = meta_data.domain; /* TODO: Use highest priority domain. */
+              attribute_kind->data_type = bke::attribute_data_type_highest_complexity(
+                  {attribute_kind->data_type, meta_data.data_type});
+            };
 
-        r_attributes.add_or_modify(name, add_info, modify_info);
-        return true;
-      });
+            r_attributes.add_or_modify(attribute_id, add_info, modify_info);
+            return true;
+          });
     }
   }
 }
@@ -500,11 +501,11 @@ static Mesh *join_mesh_topology_and_builtin_attributes(Span<GeometryInstanceGrou
 
 static void join_attributes(Span<GeometryInstanceGroup> set_groups,
                             Span<GeometryComponentType> component_types,
-                            const Map<std::string, AttributeKind> &attribute_info,
+                            const Map<AttributeIDRef, AttributeKind> &attribute_info,
                             GeometryComponent &result)
 {
-  for (Map<std::string, AttributeKind>::Item entry : attribute_info.items()) {
-    StringRef name = entry.key;
+  for (Map<AttributeIDRef, AttributeKind>::Item entry : attribute_info.items()) {
+    const AttributeIDRef attribute_id = entry.key;
     const AttributeDomain domain_output = entry.value.domain;
     const CustomDataType data_type_output = entry.value.data_type;
     const CPPType *cpp_type = bke::custom_data_type_to_cpp_type(data_type_output);
@@ -512,7 +513,7 @@ static void join_attributes(Span<GeometryInstanceGroup> set_groups,
 
     result.attribute_try_create(
         entry.key, domain_output, data_type_output, AttributeInitDefault());
-    WriteAttributeLookup write_attribute = result.attribute_try_get_for_write(name);
+    WriteAttributeLookup write_attribute = result.attribute_try_get_for_write(attribute_id);
     if (!write_attribute || &write_attribute.varray->type() != cpp_type ||
         write_attribute.domain != domain_output) {
       continue;
@@ -531,7 +532,7 @@ static void join_attributes(Span<GeometryInstanceGroup> set_groups,
             continue; /* Domain size is 0, so no need to increment the offset. */
           }
           GVArrayPtr source_attribute = component.attribute_try_get_for_read(
-              name, domain_output, data_type_output);
+              attribute_id, domain_output, data_type_output);
 
           if (source_attribute) {
             fn::GVArray_GSpan src_span{*source_attribute};
@@ -641,7 +642,7 @@ static void join_instance_groups_mesh(Span<GeometryInstanceGroup> set_groups,
   }
 
   /* Don't copy attributes that are stored directly in the mesh data structs. */
-  Map<std::string, AttributeKind> attributes;
+  Map<AttributeIDRef, AttributeKind> attributes;
   geometry_set_gather_instances_attribute_info(
       set_groups,
       component_types,
@@ -662,7 +663,7 @@ static void join_instance_groups_pointcloud(Span<GeometryInstanceGroup> set_grou
   PointCloudComponent &dst_component = result.get_component_for_write<PointCloudComponent>();
   dst_component.replace(new_pointcloud);
 
-  Map<std::string, AttributeKind> attributes;
+  Map<AttributeIDRef, AttributeKind> attributes;
   geometry_set_gather_instances_attribute_info(
       set_groups, {GEO_COMPONENT_TYPE_POINT_CLOUD}, {"position"}, attributes);
   join_attributes(set_groups,
@@ -696,7 +697,7 @@ static void join_instance_groups_curve(Span<GeometryInstanceGroup> set_groups, G
   CurveComponent &dst_component = result.get_component_for_write<CurveComponent>();
   dst_component.replace(curve);
 
-  Map<std::string, AttributeKind> attributes;
+  Map<AttributeIDRef, AttributeKind> attributes;
   geometry_set_gather_instances_attribute_info(
       set_groups,
       {GEO_COMPONENT_TYPE_CURVE},

source/blender/editors/space_spreadsheet/spreadsheet_data_source_geometry.cc

@@ -45,15 +45,20 @@ namespace blender::ed::spreadsheet {
 void GeometryDataSource::foreach_default_column_ids(
     FunctionRef<void(const SpreadsheetColumnID &)> fn) const
 {
-  component_->attribute_foreach([&](StringRefNull name, const AttributeMetaData &meta_data) {
-    if (meta_data.domain != domain_) {
-      return true;
-    }
-    SpreadsheetColumnID column_id;
-    column_id.name = (char *)name.c_str();
-    fn(column_id);
-    return true;
-  });
+  component_->attribute_foreach(
+      [&](const bke::AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        if (meta_data.domain != domain_) {
+          return true;
+        }
+        if (attribute_id.is_anonymous()) {
+          return true;
+        }
+        SpreadsheetColumnID column_id;
+        std::string name = attribute_id.name();
+        column_id.name = (char *)name.c_str();
+        fn(column_id);
+        return true;
+      });
 }
 
 std::unique_ptr<ColumnValues> GeometryDataSource::get_column_values(

source/blender/makesdna/DNA_customdata_types.h

@@ -31,6 +31,8 @@
 extern "C" {
 #endif
 
+struct AnonymousAttributeID;
+
 /** Descriptor and storage for a custom data layer. */
 typedef struct CustomDataLayer {
   /** Type of data in layer. */
@@ -53,6 +55,9 @@ typedef struct CustomDataLayer {
   char name[64];
   /** Layer data. */
   void *data;
+  /** Run-time identifier for this layer.  If no
+   * one has a strong reference to this id anymore, the layer can be removed. */
+  const struct AnonymousAttributeID *anonymous_id;
 } CustomDataLayer;
 
 #define MAX_CUSTOMDATA_LAYER_NAME 64

source/blender/nodes/NOD_geometry_exec.hh

@@ -32,10 +32,13 @@ struct ModifierData;
 
 namespace blender::nodes {
 
+using bke::AttributeIDRef;
 using bke::geometry_set_realize_instances;
 using bke::OutputAttribute;
 using bke::OutputAttribute_Typed;
 using bke::ReadAttributeLookup;
+using bke::StrongAnonymousAttributeID;
+using bke::WeakAnonymousAttributeID;
 using bke::WriteAttributeLookup;
 using fn::CPPType;
 using fn::GMutablePointer;

source/blender/nodes/geometry/node_geometry_util.hh

@@ -76,7 +76,7 @@ struct CurveToPointsResults {
   MutableSpan<float> radii;
   MutableSpan<float> tilts;
 
-  Map<std::string, GMutableSpan> point_attributes;
+  Map<AttributeIDRef, GMutableSpan> point_attributes;
 
   MutableSpan<float3> tangents;
   MutableSpan<float3> normals;

source/blender/nodes/geometry/nodes/node_geo_curve_endpoints.cc

@@ -60,25 +60,26 @@ static void copy_spline_domain_attributes(const CurveComponent &curve_component,
                                           Span<int> offsets,
                                           PointCloudComponent &points)
 {
-  curve_component.attribute_foreach([&](StringRefNull name, const AttributeMetaData &meta_data) {
-    if (meta_data.domain != ATTR_DOMAIN_CURVE) {
-      return true;
-    }
-    GVArrayPtr spline_attribute = curve_component.attribute_get_for_read(
-        name, ATTR_DOMAIN_CURVE, meta_data.data_type);
+  curve_component.attribute_foreach(
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        if (meta_data.domain != ATTR_DOMAIN_CURVE) {
+          return true;
+        }
+        GVArrayPtr spline_attribute = curve_component.attribute_get_for_read(
+            attribute_id, ATTR_DOMAIN_CURVE, meta_data.data_type);
 
-    OutputAttribute result_attribute = points.attribute_try_get_for_output_only(
-        name, ATTR_DOMAIN_POINT, meta_data.data_type);
-    GMutableSpan result = result_attribute.as_span();
+        OutputAttribute result_attribute = points.attribute_try_get_for_output_only(
+            attribute_id, ATTR_DOMAIN_POINT, meta_data.data_type);
+        GMutableSpan result = result_attribute.as_span();
 
-    /* Only copy the attributes of splines in the offsets. */
-    for (const int i : offsets.index_range()) {
-      spline_attribute->get(offsets[i], result[i]);
-    }
+        /* Only copy the attributes of splines in the offsets. */
+        for (const int i : offsets.index_range()) {
+          spline_attribute->get(offsets[i], result[i]);
+        }
 
-    result_attribute.save();
-    return true;
-  });
+        result_attribute.save();
+        return true;
+      });
 }
 
 /**
@@ -128,20 +129,20 @@ static void copy_endpoint_attributes(Span<SplinePtr> splines,
 
       /* Copy the point attribute data over. */
       for (const auto &item : start_data.point_attributes.items()) {
-        const StringRef name = item.key;
+        const AttributeIDRef attribute_id = item.key;
         GMutableSpan point_span = item.value;
 
-        BLI_assert(spline.attributes.get_for_read(name));
-        GSpan spline_span = *spline.attributes.get_for_read(name);
+        BLI_assert(spline.attributes.get_for_read(attribute_id));
+        GSpan spline_span = *spline.attributes.get_for_read(attribute_id);
         blender::fn::GVArray_For_GSpan(spline_span).get(0, point_span[i]);
       }
 
       for (const auto &item : end_data.point_attributes.items()) {
-        const StringRef name = item.key;
+        const AttributeIDRef attribute_id = item.key;
         GMutableSpan point_span = item.value;
 
-        BLI_assert(spline.attributes.get_for_read(name));
-        GSpan spline_span = *spline.attributes.get_for_read(name);
+        BLI_assert(spline.attributes.get_for_read(attribute_id));
+        GSpan spline_span = *spline.attributes.get_for_read(attribute_id);
         blender::fn::GVArray_For_GSpan(spline_span).get(spline.size() - 1, point_span[i]);
       }
     }

source/blender/nodes/geometry/nodes/node_geo_curve_resample.cc

@@ -88,14 +88,14 @@ static SplinePtr resample_spline(const Spline &input_spline, const int count)
                              input_spline.radii().first());
     output_spline->attributes.reallocate(1);
     input_spline.attributes.foreach_attribute(
-        [&](StringRefNull name, const AttributeMetaData &meta_data) {
-          std::optional<GSpan> src = input_spline.attributes.get_for_read(name);
+        [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+          std::optional<GSpan> src = input_spline.attributes.get_for_read(attribute_id);
           BLI_assert(src);
-          if (!output_spline->attributes.create(name, meta_data.data_type)) {
+          if (!output_spline->attributes.create(attribute_id, meta_data.data_type)) {
             BLI_assert_unreachable();
             return false;
           }
-          std::optional<GMutableSpan> dst = output_spline->attributes.get_for_write(name);
+          std::optional<GMutableSpan> dst = output_spline->attributes.get_for_write(attribute_id);
           if (!dst) {
             BLI_assert_unreachable();
             return false;
@@ -126,15 +126,15 @@ static SplinePtr resample_spline(const Spline &input_spline, const int count)
 
   output_spline->attributes.reallocate(count);
   input_spline.attributes.foreach_attribute(
-      [&](StringRefNull name, const AttributeMetaData &meta_data) {
-        std::optional<GSpan> input_attribute = input_spline.attributes.get_for_read(name);
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        std::optional<GSpan> input_attribute = input_spline.attributes.get_for_read(attribute_id);
         BLI_assert(input_attribute);
-        if (!output_spline->attributes.create(name, meta_data.data_type)) {
+        if (!output_spline->attributes.create(attribute_id, meta_data.data_type)) {
           BLI_assert_unreachable();
           return false;
         }
         std::optional<GMutableSpan> output_attribute = output_spline->attributes.get_for_write(
-            name);
+            attribute_id);
         if (!output_attribute) {
           BLI_assert_unreachable();
           return false;

source/blender/nodes/geometry/nodes/node_geo_curve_reverse.cc

@@ -87,9 +87,9 @@ static void geo_node_curve_reverse_exec(GeoNodeExecParams params)
       reverse_data<float>(splines[i]->tilts());
 
       splines[i]->attributes.foreach_attribute(
-          [&](StringRefNull name, const AttributeMetaData &meta_data) {
+          [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
             std::optional<blender::fn::GMutableSpan> output_attribute =
-                splines[i]->attributes.get_for_write(name);
+                splines[i]->attributes.get_for_write(attribute_id);
             if (!output_attribute) {
               BLI_assert_unreachable();
               return false;

source/blender/nodes/geometry/nodes/node_geo_curve_spline_type.cc

@@ -78,14 +78,14 @@ template<typename CopyFn>
 static void copy_attributes(const Spline &input_spline, Spline &output_spline, CopyFn copy_fn)
 {
   input_spline.attributes.foreach_attribute(
-      [&](StringRefNull name, const AttributeMetaData &meta_data) {
-        std::optional<GSpan> src = input_spline.attributes.get_for_read(name);
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        std::optional<GSpan> src = input_spline.attributes.get_for_read(attribute_id);
         BLI_assert(src);
-        if (!output_spline.attributes.create(name, meta_data.data_type)) {
+        if (!output_spline.attributes.create(attribute_id, meta_data.data_type)) {
           BLI_assert_unreachable();
           return false;
         }
-        std::optional<GMutableSpan> dst = output_spline.attributes.get_for_write(name);
+        std::optional<GMutableSpan> dst = output_spline.attributes.get_for_write(attribute_id);
         if (!dst) {
           BLI_assert_unreachable();
           return false;

source/blender/nodes/geometry/nodes/node_geo_curve_subdivide.cc

@@ -287,16 +287,16 @@ static void subdivide_dynamic_attributes(const Spline &src_spline,
 {
   const bool is_cyclic = src_spline.is_cyclic();
   src_spline.attributes.foreach_attribute(
-      [&](StringRefNull name, const AttributeMetaData &meta_data) {
-        std::optional<GSpan> src = src_spline.attributes.get_for_read(name);
+      [&](const bke::AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        std::optional<GSpan> src = src_spline.attributes.get_for_read(attribute_id);
         BLI_assert(src);
 
-        if (!dst_spline.attributes.create(name, meta_data.data_type)) {
+        if (!dst_spline.attributes.create(attribute_id, meta_data.data_type)) {
           /* Since the source spline of the same type had the attribute, adding it should work. */
           BLI_assert_unreachable();
         }
 
-        std::optional<GMutableSpan> dst = dst_spline.attributes.get_for_write(name);
+        std::optional<GMutableSpan> dst = dst_spline.attributes.get_for_write(attribute_id);
         BLI_assert(dst);
 
         attribute_math::convert_to_static_type(dst->type(), [&](auto dummy) {

source/blender/nodes/geometry/nodes/node_geo_curve_to_points.cc

@@ -119,21 +119,21 @@ static Array<int> calculate_spline_point_offsets(GeoNodeExecParams &params,
 }
 
 static GMutableSpan create_attribute_and_retrieve_span(PointCloudComponent &points,
-                                                       const StringRef name,
+                                                       const AttributeIDRef &attribute_id,
                                                        const CustomDataType data_type)
 {
-  points.attribute_try_create(name, ATTR_DOMAIN_POINT, data_type, AttributeInitDefault());
-  WriteAttributeLookup attribute = points.attribute_try_get_for_write(name);
+  points.attribute_try_create(attribute_id, ATTR_DOMAIN_POINT, data_type, AttributeInitDefault());
+  WriteAttributeLookup attribute = points.attribute_try_get_for_write(attribute_id);
   BLI_assert(attribute);
   return attribute.varray->get_internal_span();
 }
 
 template<typename T>
 static MutableSpan<T> create_attribute_and_retrieve_span(PointCloudComponent &points,
-                                                         const StringRef name)
+                                                         const AttributeIDRef &attribute_id)
 {
   GMutableSpan attribute = create_attribute_and_retrieve_span(
-      points, name, bke::cpp_type_to_custom_data_type(CPPType::get<T>()));
+      points, attribute_id, bke::cpp_type_to_custom_data_type(CPPType::get<T>()));
   return attribute.typed<T>();
 }
 
@@ -151,9 +151,10 @@ CurveToPointsResults curve_to_points_create_result_attributes(PointCloudComponen
   /* Because of the invariants of the curve component, we use the attributes of the
    * first spline as a representative for the attribute meta data all splines. */
   curve.splines().first()->attributes.foreach_attribute(
-      [&](StringRefNull name, const AttributeMetaData &meta_data) {
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
         attributes.point_attributes.add_new(
-            name, create_attribute_and_retrieve_span(points, name, meta_data.data_type));
+            attribute_id,
+            create_attribute_and_retrieve_span(points, attribute_id, meta_data.data_type));
         return true;
       },
       ATTR_DOMAIN_POINT);
@@ -183,12 +184,12 @@ static void copy_evaluated_point_attributes(Span<SplinePtr> splines,
       spline.interpolate_to_evaluated(spline.radii())->materialize(data.radii.slice(offset, size));
       spline.interpolate_to_evaluated(spline.tilts())->materialize(data.tilts.slice(offset, size));
 
-      for (const Map<std::string, GMutableSpan>::Item &item : data.point_attributes.items()) {
-        const StringRef name = item.key;
+      for (const Map<AttributeIDRef, GMutableSpan>::Item &item : data.point_attributes.items()) {
+        const AttributeIDRef attribute_id = item.key;
         GMutableSpan point_span = item.value;
 
-        BLI_assert(spline.attributes.get_for_read(name));
-        GSpan spline_span = *spline.attributes.get_for_read(name);
+        BLI_assert(spline.attributes.get_for_read(attribute_id));
+        GSpan spline_span = *spline.attributes.get_for_read(attribute_id);
 
         spline.interpolate_to_evaluated(spline_span)
             ->materialize(point_span.slice(offset, size).data());
@@ -226,12 +227,12 @@ static void copy_uniform_sample_point_attributes(Span<SplinePtr> splines,
                                               uniform_samples,
                                               data.tilts.slice(offset, size));
 
-      for (const Map<std::string, GMutableSpan>::Item &item : data.point_attributes.items()) {
-        const StringRef name = item.key;
+      for (const Map<AttributeIDRef, GMutableSpan>::Item &item : data.point_attributes.items()) {
+        const AttributeIDRef attribute_id = item.key;
         GMutableSpan point_span = item.value;
 
-        BLI_assert(spline.attributes.get_for_read(name));
-        GSpan spline_span = *spline.attributes.get_for_read(name);
+        BLI_assert(spline.attributes.get_for_read(attribute_id));
+        GSpan spline_span = *spline.attributes.get_for_read(attribute_id);
 
         spline.sample_with_index_factors(*spline.interpolate_to_evaluated(spline_span),
                                          uniform_samples,
@@ -261,31 +262,32 @@ static void copy_spline_domain_attributes(const CurveComponent &curve_component,
                                           Span<int> offsets,
                                           PointCloudComponent &points)
 {
-  curve_component.attribute_foreach([&](StringRefNull name, const AttributeMetaData &meta_data) {
-    if (meta_data.domain != ATTR_DOMAIN_CURVE) {
-      return true;
-    }
-    GVArrayPtr spline_attribute = curve_component.attribute_get_for_read(
-        name, ATTR_DOMAIN_CURVE, meta_data.data_type);
-    const CPPType &type = spline_attribute->type();
+  curve_component.attribute_foreach(
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        if (meta_data.domain != ATTR_DOMAIN_CURVE) {
+          return true;
+        }
+        GVArrayPtr spline_attribute = curve_component.attribute_get_for_read(
+            attribute_id, ATTR_DOMAIN_CURVE, meta_data.data_type);
+        const CPPType &type = spline_attribute->type();
 
-    OutputAttribute result_attribute = points.attribute_try_get_for_output_only(
-        name, ATTR_DOMAIN_POINT, meta_data.data_type);
-    GMutableSpan result = result_attribute.as_span();
+        OutputAttribute result_attribute = points.attribute_try_get_for_output_only(
+            attribute_id, ATTR_DOMAIN_POINT, meta_data.data_type);
+        GMutableSpan result = result_attribute.as_span();
 
-    for (const int i : IndexRange(spline_attribute->size())) {
-      const int offset = offsets[i];
-      const int size = offsets[i + 1] - offsets[i];
-      if (size != 0) {
-        BUFFER_FOR_CPP_TYPE_VALUE(type, buffer);
-        spline_attribute->get(i, buffer);
-        type.fill_assign_n(buffer, result[offset], size);
-      }
-    }
+        for (const int i : IndexRange(spline_attribute->size())) {
+          const int offset = offsets[i];
+          const int size = offsets[i + 1] - offsets[i];
+          if (size != 0) {
+            BUFFER_FOR_CPP_TYPE_VALUE(type, buffer);
+            spline_attribute->get(i, buffer);
+            type.fill_assign_n(buffer, result[offset], size);
+          }
+        }
 
-    result_attribute.save();
-    return true;
-  });
+        result_attribute.save();
+        return true;
+      });
 }
 
 void curve_create_default_rotation_attribute(Span<float3> tangents,

source/blender/nodes/geometry/nodes/node_geo_curve_trim.cc

@@ -162,8 +162,8 @@ static void trim_poly_spline(Spline &spline,
   linear_trim_data<float>(start, end, spline.tilts());
 
   spline.attributes.foreach_attribute(
-      [&](StringRefNull name, const AttributeMetaData &UNUSED(meta_data)) {
-        std::optional<GMutableSpan> src = spline.attributes.get_for_write(name);
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &UNUSED(meta_data)) {
+        std::optional<GMutableSpan> src = spline.attributes.get_for_write(attribute_id);
         BLI_assert(src);
         attribute_math::convert_to_static_type(src->type(), [&](auto dummy) {
           using T = decltype(dummy);
@@ -197,14 +197,14 @@ static PolySpline trim_nurbs_spline(const Spline &spline,
 
   /* Copy generic attribute data. */
   spline.attributes.foreach_attribute(
-      [&](StringRefNull name, const AttributeMetaData &meta_data) {
-        std::optional<GSpan> src = spline.attributes.get_for_read(name);
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        std::optional<GSpan> src = spline.attributes.get_for_read(attribute_id);
         BLI_assert(src);
-        if (!new_spline.attributes.create(name, meta_data.data_type)) {
+        if (!new_spline.attributes.create(attribute_id, meta_data.data_type)) {
           BLI_assert_unreachable();
           return false;
         }
-        std::optional<GMutableSpan> dst = new_spline.attributes.get_for_write(name);
+        std::optional<GMutableSpan> dst = new_spline.attributes.get_for_write(attribute_id);
         BLI_assert(dst);
 
         attribute_math::convert_to_static_type(src->type(), [&](auto dummy) {
@@ -253,8 +253,8 @@ static void trim_bezier_spline(Spline &spline,
   linear_trim_data<float>(start, end, bezier_spline.radii());
   linear_trim_data<float>(start, end, bezier_spline.tilts());
   spline.attributes.foreach_attribute(
-      [&](StringRefNull name, const AttributeMetaData &UNUSED(meta_data)) {
-        std::optional<GMutableSpan> src = spline.attributes.get_for_write(name);
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &UNUSED(meta_data)) {
+        std::optional<GMutableSpan> src = spline.attributes.get_for_write(attribute_id);
         BLI_assert(src);
         attribute_math::convert_to_static_type(src->type(), [&](auto dummy) {
           using T = decltype(dummy);

source/blender/nodes/geometry/nodes/node_geo_delete_geometry.cc

@@ -97,16 +97,16 @@ static void copy_dynamic_attributes(const CustomDataAttributes &src,
                                     const IndexMask mask)
 {
   src.foreach_attribute(
-      [&](StringRefNull name, const AttributeMetaData &meta_data) {
-        std::optional<GSpan> src_attribute = src.get_for_read(name);
+      [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        std::optional<GSpan> src_attribute = src.get_for_read(attribute_id);
         BLI_assert(src_attribute);
 
-        if (!dst.create(name, meta_data.data_type)) {
+        if (!dst.create(attribute_id, meta_data.data_type)) {
           /* Since the source spline of the same type had the attribute, adding it should work. */
           BLI_assert_unreachable();
         }
 
-        std::optional<GMutableSpan> new_attribute = dst.get_for_write(name);
+        std::optional<GMutableSpan> new_attribute = dst.get_for_write(attribute_id);
         BLI_assert(new_attribute);
 
         attribute_math::convert_to_static_type(new_attribute->type(), [&](auto dummy) {

source/blender/nodes/geometry/nodes/node_geo_join_geometry.cc

@@ -161,34 +161,35 @@ static Array<const GeometryComponent *> to_base_components(Span<const Component
   return components;
 }
 
-static Map<std::string, AttributeMetaData> get_final_attribute_info(
+static Map<AttributeIDRef, AttributeMetaData> get_final_attribute_info(
     Span<const GeometryComponent *> components, Span<StringRef> ignored_attributes)
 {
-  Map<std::string, AttributeMetaData> info;
+  Map<AttributeIDRef, AttributeMetaData> info;
 
   for (const GeometryComponent *component : components) {
-    component->attribute_foreach([&](StringRefNull name, const AttributeMetaData &meta_data) {
-      if (ignored_attributes.contains(name)) {
-        return true;
-      }
-      info.add_or_modify(
-          name,
-          [&](AttributeMetaData *meta_data_final) { *meta_data_final = meta_data; },
-          [&](AttributeMetaData *meta_data_final) {
-            meta_data_final->data_type = blender::bke::attribute_data_type_highest_complexity(
-                {meta_data_final->data_type, meta_data.data_type});
-            meta_data_final->domain = blender::bke::attribute_domain_highest_priority(
-                {meta_data_final->domain, meta_data.domain});
-          });
-      return true;
-    });
+    component->attribute_foreach(
+        [&](const bke::AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+          if (attribute_id.is_named() && ignored_attributes.contains(attribute_id.name())) {
+            return true;
+          }
+          info.add_or_modify(
+              attribute_id,
+              [&](AttributeMetaData *meta_data_final) { *meta_data_final = meta_data; },
+              [&](AttributeMetaData *meta_data_final) {
+                meta_data_final->data_type = blender::bke::attribute_data_type_highest_complexity(
+                    {meta_data_final->data_type, meta_data.data_type});
+                meta_data_final->domain = blender::bke::attribute_domain_highest_priority(
+                    {meta_data_final->domain, meta_data.domain});
+              });
+          return true;
+        });
   }
 
   return info;
 }
 
 static void fill_new_attribute(Span<const GeometryComponent *> src_components,
-                               StringRef attribute_name,
+                               const AttributeIDRef &attribute_id,
                                const CustomDataType data_type,
                                const AttributeDomain domain,
                                GMutableSpan dst_span)
@@ -203,7 +204,7 @@ static void fill_new_attribute(Span<const GeometryComponent *> src_components,
       continue;
     }
     GVArrayPtr read_attribute = component->attribute_get_for_read(
-        attribute_name, domain, data_type, nullptr);
+        attribute_id, domain, data_type, nullptr);
 
     GVArray_GSpan src_span{*read_attribute};
     const void *src_buffer = src_span.data();
@@ -218,20 +219,21 @@ static void join_attributes(Span<const GeometryComponent *> src_components,
                             GeometryComponent &result,
                             Span<StringRef> ignored_attributes = {})
 {
-  const Map<std::string, AttributeMetaData> info = get_final_attribute_info(src_components,
-                                                                            ignored_attributes);
+  const Map<AttributeIDRef, AttributeMetaData> info = get_final_attribute_info(src_components,
+                                                                               ignored_attributes);
 
-  for (const Map<std::string, AttributeMetaData>::Item &item : info.items()) {
-    const StringRef name = item.key;
+  for (const Map<AttributeIDRef, AttributeMetaData>::Item &item : info.items()) {
+    const AttributeIDRef attribute_id = item.key;
     const AttributeMetaData &meta_data = item.value;
 
     OutputAttribute write_attribute = result.attribute_try_get_for_output_only(
-        name, meta_data.domain, meta_data.data_type);
+        attribute_id, meta_data.domain, meta_data.data_type);
     if (!write_attribute) {
       continue;
     }
     GMutableSpan dst_span = write_attribute.as_span();
-    fill_new_attribute(src_components, name, meta_data.data_type, meta_data.domain, dst_span);
+    fill_new_attribute(
+        src_components, attribute_id, meta_data.data_type, meta_data.domain, dst_span);
     write_attribute.save();
   }
 }
@@ -306,7 +308,7 @@ static void join_components(Span<const VolumeComponent *> src_components, Geomet
  * \note This takes advantage of the fact that creating attributes on joined curves never
  * changes a point attribute into a spline attribute; it is always the other way around.
  */
-static void ensure_control_point_attribute(const StringRef name,
+static void ensure_control_point_attribute(const AttributeIDRef &attribute_id,
                                            const CustomDataType data_type,
                                            Span<CurveComponent *> src_components,
                                            CurveEval &result)
@@ -321,7 +323,7 @@ static void ensure_control_point_attribute(const StringRef name,
   const CurveEval *current_curve = src_components[src_component_index]->get_for_read();
 
   for (SplinePtr &spline : splines) {
-    std::optional<GSpan> attribute = spline->attributes.get_for_read(name);
+    std::optional<GSpan> attribute = spline->attributes.get_for_read(attribute_id);
 
     if (attribute) {
       if (attribute->type() != type) {
@@ -334,22 +336,22 @@ static void ensure_control_point_attribute(const StringRef name,
         conversions.try_convert(std::make_unique<GVArray_For_GSpan>(*attribute), type)
             ->materialize(converted_buffer);
 
-        spline->attributes.remove(name);
-        spline->attributes.create_by_move(name, data_type, converted_buffer);
+        spline->attributes.remove(attribute_id);
+        spline->attributes.create_by_move(attribute_id, data_type, converted_buffer);
       }
     }
     else {
-      spline->attributes.create(name, data_type);
+      spline->attributes.create(attribute_id, data_type);
 
-      if (current_curve->attributes.get_for_read(name)) {
+      if (current_curve->attributes.get_for_read(attribute_id)) {
         /* In this case the attribute did not exist, but there is a spline domain attribute
          * we can retrieve a value from, as a spline to point domain conversion. So fill the
          * new attribute with the value for this spline. */
         GVArrayPtr current_curve_attribute = current_curve->attributes.get_for_read(
-            name, data_type, nullptr);
+            attribute_id, data_type, nullptr);
 
-        BLI_assert(spline->attributes.get_for_read(name));
-        std::optional<GMutableSpan> new_attribute = spline->attributes.get_for_write(name);
+        BLI_assert(spline->attributes.get_for_read(attribute_id));
+        std::optional<GMutableSpan> new_attribute = spline->attributes.get_for_write(attribute_id);
 
         BUFFER_FOR_CPP_TYPE_VALUE(type, buffer);
         current_curve_attribute->get(spline_index_in_component, buffer);
@@ -371,15 +373,15 @@ static void ensure_control_point_attribute(const StringRef name,
 /**
  * Fill data for an attribute on the new curve based on all source curves.
  */
-static void ensure_spline_attribute(const StringRef name,
+static void ensure_spline_attribute(const AttributeIDRef &attribute_id,
                                     const CustomDataType data_type,
                                     Span<CurveComponent *> src_components,
                                     CurveEval &result)
 {
   const CPPType &type = *bke::custom_data_type_to_cpp_type(data_type);
 
-  result.attributes.create(name, data_type);
-  GMutableSpan result_attribute = *result.attributes.get_for_write(name);
+  result.attributes.create(attribute_id, data_type);
+  GMutableSpan result_attribute = *result.attributes.get_for_write(attribute_id);
 
   int offset = 0;
   for (const CurveComponent *component : src_components) {
@@ -388,7 +390,7 @@ static void ensure_spline_attribute(const StringRef name,
     if (size == 0) {
       continue;
     }
-    GVArrayPtr read_attribute = curve.attributes.get_for_read(name, data_type, nullptr);
+    GVArrayPtr read_attribute = curve.attributes.get_for_read(attribute_id, data_type, nullptr);
     GVArray_GSpan src_span{*read_attribute};
 
     const void *src_buffer = src_span.data();
@@ -406,19 +408,19 @@ static void ensure_spline_attribute(const StringRef name,
  * \warning Splines have been moved out of the source components at this point, so it
  * is important to only read curve-level data (spline domain attributes) from them.
  */
-static void join_curve_attributes(const Map<std::string, AttributeMetaData> &info,
+static void join_curve_attributes(const Map<AttributeIDRef, AttributeMetaData> &info,
                                   Span<CurveComponent *> src_components,
                                   CurveEval &result)
 {
-  for (const Map<std::string, AttributeMetaData>::Item &item : info.items()) {
-    const StringRef name = item.key;
+  for (const Map<AttributeIDRef, AttributeMetaData>::Item &item : info.items()) {
+    const AttributeIDRef attribute_id = item.key;
     const AttributeMetaData meta_data = item.value;
 
     if (meta_data.domain == ATTR_DOMAIN_CURVE) {
-      ensure_spline_attribute(name, meta_data.data_type, src_components, result);
+      ensure_spline_attribute(attribute_id, meta_data.data_type, src_components, result);
     }
     else {
-      ensure_control_point_attribute(name, meta_data.data_type, src_components, result);
+      ensure_control_point_attribute(attribute_id, meta_data.data_type, src_components, result);
     }
   }
 }
@@ -446,7 +448,7 @@ static void join_curve_components(MutableSpan<GeometrySet> src_geometry_sets, Ge
   }
 
   /* Retrieve attribute info before moving the splines out of the input components. */
-  const Map<std::string, AttributeMetaData> info = get_final_attribute_info(
+  const Map<AttributeIDRef, AttributeMetaData> info = get_final_attribute_info(
       {(const GeometryComponent **)src_components.data(), src_components.size()},
       {"position", "radius", "tilt", "cyclic", "resolution"});
 

source/blender/nodes/geometry/nodes/node_geo_mesh_to_curve.cc

@@ -56,10 +56,10 @@ static void copy_attributes_to_points(CurveEval &curve,
                                       Span<Vector<int>> point_to_vert_maps)
 {
   MutableSpan<SplinePtr> splines = curve.splines();
-  Set<std::string> source_attribute_names = mesh_component.attribute_names();
+  Set<AttributeIDRef> source_attribute_ids = mesh_component.attribute_ids();
 
   /* Copy builtin control point attributes. */
-  if (source_attribute_names.contains_as("tilt")) {
+  if (source_attribute_ids.contains("tilt")) {
     const GVArray_Typed<float> tilt_attribute = mesh_component.attribute_get_for_read<float>(
         "tilt", ATTR_DOMAIN_POINT, 0.0f);
     threading::parallel_for(splines.index_range(), 256, [&](IndexRange range) {
@@ -68,9 +68,9 @@ static void copy_attributes_to_points(CurveEval &curve,
             *tilt_attribute, point_to_vert_maps[i], splines[i]->tilts());
       }
     });
-    source_attribute_names.remove_contained_as("tilt");
+    source_attribute_ids.remove_contained("tilt");
   }
-  if (source_attribute_names.contains_as("radius")) {
+  if (source_attribute_ids.contains("radius")) {
     const GVArray_Typed<float> radius_attribute = mesh_component.attribute_get_for_read<float>(
         "radius", ATTR_DOMAIN_POINT, 1.0f);
     threading::parallel_for(splines.index_range(), 256, [&](IndexRange range) {
@@ -79,15 +79,15 @@ static void copy_attributes_to_points(CurveEval &curve,
             *radius_attribute, point_to_vert_maps[i], splines[i]->radii());
       }
     });
-    source_attribute_names.remove_contained_as("radius");
+    source_attribute_ids.remove_contained("radius");
   }
 
   /* Don't copy other builtin control point attributes. */
-  source_attribute_names.remove_as("position");
+  source_attribute_ids.remove("position");
 
   /* Copy dynamic control point attributes. */
-  for (const StringRef name : source_attribute_names) {
-    const GVArrayPtr mesh_attribute = mesh_component.attribute_try_get_for_read(name,
+  for (const AttributeIDRef &attribute_id : source_attribute_ids) {
+    const GVArrayPtr mesh_attribute = mesh_component.attribute_try_get_for_read(attribute_id,
                                                                                 ATTR_DOMAIN_POINT);
     /* Some attributes might not exist if they were builtin attribute on domains that don't
      * have any elements, i.e. a face attribute on the output of the line primitive node. */
@@ -100,8 +100,9 @@ static void copy_attributes_to_points(CurveEval &curve,
     threading::parallel_for(splines.index_range(), 128, [&](IndexRange range) {
       for (const int i : range) {
         /* Create attribute on the spline points. */
-        splines[i]->attributes.create(name, data_type);
-        std::optional<GMutableSpan> spline_attribute = splines[i]->attributes.get_for_write(name);
+        splines[i]->attributes.create(attribute_id, data_type);
+        std::optional<GMutableSpan> spline_attribute = splines[i]->attributes.get_for_write(
+            attribute_id);
         BLI_assert(spline_attribute);
 
         /* Copy attribute based on the map for this spline. */

source/blender/nodes/geometry/nodes/node_geo_point_distribute.cc

@@ -277,17 +277,17 @@ BLI_NOINLINE static void interpolate_attribute(const Mesh &mesh,
 BLI_NOINLINE static void interpolate_existing_attributes(
     Span<GeometryInstanceGroup> set_groups,
     Span<int> instance_start_offsets,
-    const Map<std::string, AttributeKind> &attributes,
+    const Map<AttributeIDRef, AttributeKind> &attributes,
     GeometryComponent &component,
     Span<Vector<float3>> bary_coords_array,
     Span<Vector<int>> looptri_indices_array)
 {
-  for (Map<std::string, AttributeKind>::Item entry : attributes.items()) {
-    StringRef attribute_name = entry.key;
+  for (Map<AttributeIDRef, AttributeKind>::Item entry : attributes.items()) {
+    const AttributeIDRef attribute_id = entry.key;
     const CustomDataType output_data_type = entry.value.data_type;
     /* The output domain is always #ATTR_DOMAIN_POINT, since we are creating a point cloud. */
     OutputAttribute attribute_out = component.attribute_try_get_for_output_only(
-        attribute_name, ATTR_DOMAIN_POINT, output_data_type);
+        attribute_id, ATTR_DOMAIN_POINT, output_data_type);
     if (!attribute_out) {
       continue;
     }
@@ -301,7 +301,7 @@ BLI_NOINLINE static void interpolate_existing_attributes(
       const Mesh &mesh = *source_component.get_for_read();
 
       std::optional<AttributeMetaData> attribute_info = component.attribute_get_meta_data(
-          attribute_name);
+          attribute_id);
       if (!attribute_info) {
         i_instance += set_group.transforms.size();
         continue;
@@ -309,7 +309,7 @@ BLI_NOINLINE static void interpolate_existing_attributes(
 
       const AttributeDomain source_domain = attribute_info->domain;
       GVArrayPtr source_attribute = source_component.attribute_get_for_read(
-          attribute_name, source_domain, output_data_type, nullptr);
+          attribute_id, source_domain, output_data_type, nullptr);
       if (!source_attribute) {
         i_instance += set_group.transforms.size();
         continue;
@@ -406,7 +406,7 @@ BLI_NOINLINE static void compute_special_attributes(Span<GeometryInstanceGroup>
 BLI_NOINLINE static void add_remaining_point_attributes(
     Span<GeometryInstanceGroup> set_groups,
     Span<int> instance_start_offsets,
-    const Map<std::string, AttributeKind> &attributes,
+    const Map<AttributeIDRef, AttributeKind> &attributes,
     GeometryComponent &component,
     Span<Vector<float3>> bary_coords_array,
     Span<Vector<int>> looptri_indices_array)
@@ -629,7 +629,7 @@ static void geo_node_point_distribute_exec(GeoNodeExecParams params)
   PointCloudComponent &point_component =
       geometry_set_out.get_component_for_write<PointCloudComponent>();
 
-  Map<std::string, AttributeKind> attributes;
+  Map<AttributeIDRef, AttributeKind> attributes;
   bke::geometry_set_gather_instances_attribute_info(
       set_groups, {GEO_COMPONENT_TYPE_MESH}, {"position", "normal", "id"}, attributes);
   add_remaining_point_attributes(set_groups,

source/blender/nodes/geometry/nodes/node_geo_point_separate.cc

@@ -57,8 +57,8 @@ void copy_point_attributes_based_on_mask(const GeometryComponent &in_component,
                                          Span<bool> masks,
                                          const bool invert)
 {
-  for (const std::string &name : in_component.attribute_names()) {
-    ReadAttributeLookup attribute = in_component.attribute_try_get_for_read(name);
+  for (const AttributeIDRef &attribute_id : in_component.attribute_ids()) {
+    ReadAttributeLookup attribute = in_component.attribute_try_get_for_read(attribute_id);
     const CustomDataType data_type = bke::cpp_type_to_custom_data_type(attribute.varray->type());
 
     /* Only copy point attributes. Theoretically this could interpolate attributes on other
@@ -69,7 +69,7 @@ void copy_point_attributes_based_on_mask(const GeometryComponent &in_component,
     }
 
     OutputAttribute result_attribute = result_component.attribute_try_get_for_output_only(
-        name, ATTR_DOMAIN_POINT, data_type);
+        attribute_id, ATTR_DOMAIN_POINT, data_type);
 
     attribute_math::convert_to_static_type(data_type, [&](auto dummy) {
       using T = decltype(dummy);

source/blender/nodes/intern/geometry_nodes_eval_log.cc

@@ -161,8 +161,10 @@ GeometryValueLog::GeometryValueLog(const GeometrySet &geometry_set, bool log_ful
 {
   bke::geometry_set_instances_attribute_foreach(
       geometry_set,
-      [&](StringRefNull attribute_name, const AttributeMetaData &meta_data) {
-        this->attributes_.append({attribute_name, meta_data.domain, meta_data.data_type});
+      [&](const bke::AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
+        if (attribute_id.is_named()) {
+          this->attributes_.append({attribute_id.name(), meta_data.domain, meta_data.data_type});
+        }
         return true;
       },
       8);